These are representative sample records from Science.gov related to your search topic.
For comprehensive and current results, perform a real-time search at Science.gov.
1

JIS Definition Identified More Malaysian Adults with Metabolic Syndrome Compared to the NCEP-ATP III and IDF Criteria  

PubMed Central

Metabolic syndrome (MetS) is a steering force for the cardiovascular diseases epidemic in Asia. This study aimed to compare the prevalence of MetS in Malaysian adults using NCEP-ATP III, IDF, and JIS definitions, identify the demographic factors associated with MetS, and determine the level of agreement between these definitions. The analytic sample consisted of 8,836 adults aged ?30 years recruited at baseline in 2007–2011 from the Cardiovascular Risk Prevention Study (CRisPS), an ongoing, prospective cohort study involving 18 urban and 22 rural communities in Malaysia. JIS definition gave the highest overall prevalence (43.4%) compared to NCEP-ATP III (26.5%) and IDF (37.4%), P < 0.001. Indians had significantly higher age-adjusted prevalence compared to other ethnic groups across all MetS definitions (30.1% by NCEP-ATP III, 50.8% by IDF, and 56.5% by JIS). The likelihood of having MetS amongst the rural and urban populations was similar across all definitions. A high level of agreement between the IDF and JIS was observed (Kappa index = 0.867), while there was a lower level of agreement between the IDF and NCEP-ATP III (Kappa index = 0.580). JIS definition identified more Malaysian adults with MetS and therefore should be recommended as the preferred diagnostic criterion. PMID:24175300

Daher, Aqil Mohammad; Noor Khan Nor-Ashikin, Mohamed; Mat-Nasir, Nafiza; Keat Ng, Kien; Ambigga, Krishnapillai S.; Ariffin, Farnaza; Yasin Mazapuspavina, Md; Abdul-Razak, Suraya; Abdul-Hamid, Hasidah; Abd-Majid, Fadhlina; Abu-Bakar, Najmin; Nawawi, Hapizah; Yusoff, Khalid

2013-01-01

2

Cloning, characterization and mapping of the human ATP5E gene, identification of pseudogene ATP5EP1, and definition of the ATP5E motif.  

PubMed Central

A cDNA encoding the epsilon subunit of human ATP synthase, ATP5E, was isolated from heart, skeletal muscle and spleen cDNA libraries respectively. Its genome structure was characterized as comprising three exons and two introns within a stretch of 5 kb, according to the genomic sequence AL109840. The gene was mapped to human chromosome 20q13.3 between marker D20S173 and 20qter using the radiation hybrid GB4 panel. Northern blot analysis showed that the ATP5E gene was expressed as a single 0.6 kb transcript in all 16 human tissues tested, with a high level present in heart and skeletal muscle. A new conserved motif composed of 24 residues, termed the ATP5E motif [W(R/K)X(5)YX(2)(Y/F)X(3)(C/A)X(4)RX(3)K], was defined on the basis of sequences of ATP synthase epsilon subunits from ten different organisms. In addition, a pseudogene ATP5EP1 was also identified on the basis of genomic sequence AC004066, localized on human chromosome 4q25. By analysing these results combined with the Southern blot patterns of human DNA hybridized with bovine ATP5E cDNA reported previously [Vinas, Powell, Runswick, Iacobazzi and Walker (1990) Biochem. J. 265, 321-326], we provide evidence of yet further homologous sequences (either gene or pseudogene) of ATP5E, in addition to ATP5E and ATP5EP1 in the human genome. PMID:10727396

Tu, Q; Yu, L; Zhang, P; Zhang, M; Zhang, H; Jiang, J; Chen, C; Zhao, S

2000-01-01

3

Regulation of the Type III InsP3 Receptor by InsP3 and ATP Robert E. Hagar*  

E-print Network

Regulation of the Type III InsP3 Receptor by InsP3 and ATP Robert E. Hagar* and Barbara E. Ehrlich et al., 1987), and the development of long- term depression (Finch and Augustine, 1998; Inoue et al , phosphorylation of the InsP3R, and intracellular pH (Ferris et al., 1991a,b; Finch et al., 1991; Iino, 1990

Ehrlich, Barbara E.

4

ATP molecule ATP molecule  

E-print Network

with adenosine 5`-triphosphate (ATP). ATP is the most important energy carrier in cellular metabolism, and each carbon atoms are grey, hydrogen white, oxygen red, nitrogen blue, and phospho- rus orange. The situation

5

In vitro study of accuracy of cervical pedicle screw insertion using an electronic conductivity device (ATPS part III)  

Microsoft Academic Search

Reconstruction of the highly unstable, anteriorly decompressed cervical spine poses biomechanical challenges to current stabilization\\u000a strategies, including circumferential instrumented fusion, to prevent failure. To avoid secondary posterior surgery, particularly\\u000a in the elderly population, while increasing primary construct rigidity of anterior-only reconstructions, the authors introduced\\u000a the concept of anterior transpedicular screw (ATPS) fixation and plating. We demonstrated its morphological feasibility, its

Heiko Koller; Wolfgang Hitzl; Frank Acosta; Mark Tauber; Juliane Zenner; Herbert Resch; Yasutsugu Yukawa; Oliver Meier; Rene Schmidt; Michael Mayer

2009-01-01

6

Prevalence of Metabolic Syndrome among Malaysians using the International Diabetes Federation, National Cholesterol Education Program and Modified World Health Organization Definitions  

Microsoft Academic Search

The World Health Organization (WHO), National Cholesterol Education Program Adults Treatment Panel III (NCEP ATP III) and International Diabetes Federation (IDF) have proposed different criteria to diagnose metabolic syndrome (MetS). However, there is no single definition to accurately diagnose MetS. The objective of this study is to estimate the prevalence of MetS using WHO, NCEP ATP III and IDF in

Bee Ying Tan; Haresh Kumar Kantilal; Rajbans Singh

7

Contrasting prevalence of and demographic disparities in the World Health Organization and National Cholesterol Education Program Adult Treatment Panel III definitions of metabolic syndrome among adolescents  

Microsoft Academic Search

ObjectiveTo determine prevalence of metabolic syndrome (MS) among adolescents by using definitions from the National Cholesterol Education Program Adult Treatment Panel III (NCEP) and World Health Organization (WHO) guidelines and to compare the populations identified by these definitions.

Elizabeth Goodman; Stephen R. Daniels; John A. Morrison; Bin Huang; Lawrence M. Dolan

2004-01-01

8

Cx43 hemichannels are permeable to ATP  

PubMed Central

Astrocytes are electrically non-excitable cells that communicate by means of Ca2+ signaling. Long-distance intercellular Ca2+ waves are initiated by release of ATP and activation of purinergic receptors on nearby cells. Previous studies have implicated connexin 43 (Cx43) in ATP release, but definitive proof that ATP exits through Cx43 hemichannels does not exist. Here we show that ATP anions can permeate through Cx43 hemichannels using several alternative approaches. First, openings of Cx43 hemichannels were detected in both cell-attached and inside-out patch recordings in C6 cells expressing Cx43, but not in C6 cells expressing Cx43-eGFP (enhanced green fluorescent protein) or a C-terminus truncation mutant of Cx43. Second, Cx43 hemichannel openings were inhibited by three structurally different gap-junction channel blockers, but not by the P2X7 blocker Brilliant blue G. Third, bioluminescence imaging of ATP combined with single channel recording in the inside-out patch configuration showed that ATP efflux coincided with channel openings and was absent when the Cx43 hemichannel was closed. Fourth, ion replacement experiments confirmed that Cx43 hemichannels are permeable to ATP. In sum, these observations provide the first direct evidence for efflux of ATP through Cx43 hemichannels. Furthermore, a putative Cx43 hemichannel with characteristics identical to the Cx43 hemichannel in C6 cells was identified in the membrane of hippocampal astrocytes in acutely prepared slices. PMID:18448647

Kang, Jian; Kang, Ning; Lovatt, Ditte; Torres, Arnulfo; Zhao, Zhuo; Lin, Jane; Nedergaard, Maiken

2013-01-01

9

Assessing the prevalence of the Metabolic Syndrome according to NCEP ATP III in Germany: feasibility and quality aspects of a two step approach in 1550 randomly selected primary health care practices  

PubMed Central

Objective: Metabolic Syndrome (MetSyn) describes a cluster of metabolic disorders and is considered a risk factor for development of cardiovascular disease. Although a high prevalence is commonly assumed in Germany data about the degree of its occurrence in the population and in subgroups are still missing. The aim of this study was to assess the prevalence of the MetSyn according to the NCEP ATP-III (National Cholesterol Education Program Adult Treatment Panel III) criteria in persons aged ?18 years attending a general practitioner in Germany. Here we describe in detail the methods used and the feasibility of determining the MetSyn in a primary health care setting. Research design and methods: The German-wide cross-sectional study was performed during two weeks in October 2005. Blood samples were analyzed in a central laboratory. Waist circumference and blood pressure were assessed, data on smoking, life style, fasting status, socio-demographic characteristics and core information from non-participants collected. Quality control procedures included telephone-monitoring and random on-site visits. In order to achieve a maximal number of fasting blood samples with a minimal need for follow-up appointments a stepwise approach was developed. Basic descriptive statistics were calculated, the Taylor expansion method used to estimate standard errors needed for calculation of confidence intervals for clustered observations. Results: In total, 1511 randomly selected general practices from 397 out of 438 German cities and administrative districts enrolled 35,869 patients (age range: 18-99, women 61.1%). More than 50,000 blood samples were taken. Fasting blood samples were available for 49% of the participants. Of the participating patients 99.3% returned questionnaires to the GP, only 12% were not filled out completely. The overall prevalence of the MetSyn (NCEP/ATP III 2001) was found to be 19.8%, with men showing higher prevalence rates than women (22.7% respective 18.0%). Conclusions: This study was designed to provide data as robust as possible within the confines of an epidemiological study. Judging by the low degree of missing data and the high data quality, the feasibility for this kind of a research setting (short evaluation period, practitioners as data assessment sites) was found to be very good. The results will help to gain a more comprehensive insight into the prevalence of MetSyn for patients in primary health care in Germany. PMID:19675698

Moebus, Susanne; Hanisch, Jens Ulrich; Neuhäuser, Markus; Aidelsburger, Pamela; Wasem, Jürgen; Jöckel, Karl-Heinz

2006-01-01

10

Molecular Structure of ATP  

NSDL National Science Digital Library

In plant cells, ATP is produced in the cristae of mitochondria and chloroplasts. Christae are the multiply-folded inner membranes of a cell's mitochondrion, which are finger-like projections. The walls of the cristae are the site of the cell's energy production (it is where ATP is generated). Chloroplasts are made up of stacks of thylakoid disks that contain chlorophyll. Production of ATP molecules from sunlight takes place on thylakoid disks. The mechanism of ATP synthesis is the same in both mitochondria and chloroplasts. An important role of ATP as a plant molecule is to provide energy for biosynthesis. Interestingly enough, this chemical energy can also be converted into light energy in the reaction catalyzed by luciferase. Each molecule of ATP consumed in the reaction produces one photon of light.

2003-05-09

11

Functional dyspepsia--symptoms, definitions and validity of the Rome III criteria.  

PubMed

Dyspepsia refers to a heterogeneous group of symptoms that are localized in the epigastric region. Typical dyspeptic symptoms include postprandial fullness, early satiation, epigastric pain and epigastric burning, but other upper gastrointestinal symptoms such as nausea, belching or abdominal bloating often occur. Functional dyspepsia is defined as the presence of dyspeptic symptoms in the absence of an organic cause that readily explains them. The Rome III consensus proposed the subdivision of functional dyspepsia into postprandial distress syndrome (PDS), characterized by postprandial fullness and early satiation, and epigastric pain syndrome (EPS), characterized by epigastric pain or burning. Epidemiological studies in the USA and Europe confirmed the presence of both subgroups, with good separation between EPS and PDS. By contrast, other studies have found major overlap between EPS and PDS in patients with functional dyspepsia in specialist care centres in Europe and Asia. Preliminary pathophysiological studies suggest that PDS might be characterized by a higher prevalence of impaired gastric accommodation than EPS and raised duodenal eosinophil counts. Whether different treatment approaches are needed for EPS and PDS is currently unclear; only acotiamide, a new drug for the treatment of functional dyspepsia, has been found to be efficacious in PDS but not in EPS. Further randomized controlled trials testing treatment response by subgroup are urgently needed. PMID:23399526

Tack, Jan; Talley, Nicholas J

2013-03-01

12

The Impact of Extent and Location of Mediastinal Lymph Node Involvement on Survival in Stage III Non-Small Cell Lung Cancer Patients Treated With Definitive Radiotherapy  

SciTech Connect

Purpose: Several surgical series have identified subcarinal, contralateral, and multilevel nodal involvement as predictors of poor overall survival in patients with Stage III non-small-cell lung cancer (NSCLC) treated with definitive resection. This retrospective study evaluates the impact of extent and location of mediastinal lymph node (LN) involvement on survival in patients with Stage III NSCLC treated with definitive radiotherapy. Methods and Materials: We analyzed 106 consecutive patients with T1-4 N2-3 Stage III NSCLC treated with definitive radiotherapy at University of Pennsylvania between January 2003 and February 2009. For this analysis, mediastinal LN stations were divided into four mutually exclusive groups: supraclavicular, ipsilateral mediastinum, contralateral mediastinum, and subcarinal. Patients' conditions were then analyzed according to the extent of involvement and location of mediastinal LN stations. Results: The majority (88%) of patients received sequential or concurrent chemotherapy. The median follow-up time for survivors was 32.6 months. By multivariable Cox modeling, chemotherapy use (hazard ratio [HR]: 0.21 [95% confidence interval (CI): 0.07-0.63]) was associated with improved overall survival. Increasing primary tumor [18F]-fluoro-2-deoxy-glucose avidity (HR: 1.11 [CI: 1.06-1.19]), and subcarinal involvement (HR: 2.29 [CI: 1.11-4.73]) were significant negative predictors of overall survival. On univariate analysis, contralateral nodal involvement (HR: 0.70 [CI: 0.33-1.47]), supraclavicular nodal involvement (HR: 0.78 [CI: 0.38-1.67]), multilevel nodal involvement (HR: 0.97 [CI: 0.58-1.61]), and tumor size (HR: 1.04 [CI: 0.94-1.14]) did not predict for overall survival. Patients with subcarinal involvement also had lower rates of 2-year nodal control (51.2% vs. 74.9%, p = 0.047) and 2-year distant control (28.4% vs. 61.2%, p = 0.043). Conclusions: These data suggest that the factors that determine oncologic outcome in Stage III NSCLC patients treated with definitive radiotherapy are distinct from those observed in patients who undergo surgical resection. The ultimate efficacy of radiation in locally advanced NSCLC is dependent on the intrinsic biology of the tumor.

Fernandes, Annemarie T. [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA (United States); Mitra, Nandita [Department of Biostatistics and Epidemiology, University of Pennsylvania, Philadelphia, PA (United States); Xanthopoulos, Eric [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA (United States); Evans, Tracey; Stevenson, James; Langer, Corey [Department of Medical Oncology, University of Pennsylvania, Philadelphia, PA (United States); Kucharczuk, John C. [Department of Thoracic Surgery, University of Pennsylvania, Philadelphia, PA (United States); Lin, Lilie; Rengan, Ramesh [Department of Radiation Oncology, University of Pennsylvania, Philadelphia, PA (United States)

2012-05-01

13

Curtains for ATP?  

NASA Astrophysics Data System (ADS)

The administration's efforts to keep various technology-transfer programs afloat in the budget process appear to be stalled. House Science Committee chair Robert Walker (R-Pa.) advised in early April that the Republican agenda for the pending budget process entails zeroing out the Commerce Department's Advanced Technology Program (ATP), which was funded at 431 million in fiscal year 1995. The ATP would lose about 90 million from its FY 95 budget. Although Walker says that the Republican leadership has no intention to dictate to the subcommittees how cuts should be made, they will be held to the "fairly severe caps" established by the House Budget Committee. In other words, Walker says, if ATP stays, something else will have to go in its place. In addition, a bill to rescind about 223 million from the FY 1995 budget of the Technology Reinvestment Project and another 77 million from TRP's FY 1994 budget, which has not been spent, is heading for the president's signature. Yet Walker says while he supports the merits of technology transfer, "the question is do you have to create government programs to get the technology out?"

14

Optogenetic control of ATP release  

NASA Astrophysics Data System (ADS)

Controlled release of ATP can be used for understanding extracellular purinergic signaling. While coarse mechanical forces and hypotonic stimulation have been utilized in the past to initiate ATP release from cells, these methods are neither spatially accurate nor temporally precise. Further, these methods cannot be utilized in a highly effective cell-specific manner. To mitigate the uncertainties regarding cellular-specificity and spatio-temporal release of ATP, we herein demonstrate use of optogenetics for ATP release. ATP release in response to optogenetic stimulation was monitored by Luciferin-Luciferase assay (North American firefly, photinus pyralis) using luminometer as well as mesoscopic bioluminescence imaging. Our result demonstrates repetitive release of ATP subsequent to optogenetic stimulation. It is thus feasible that purinergic signaling can be directly detected via imaging if the stimulus can be confined to single cell or in a spatially-defined group of cells. This study opens up new avenue to interrogate the mechanisms of purinergic signaling.

Lewis, Matthew A.; Joshi, Bipin; Gu, Ling; Feranchak, Andrew; Mohanty, Samarendra K.

2013-03-01

15

Comparison and correlation of binding mode of ATP in the kinase domains of Hexokinase family  

PubMed Central

Hexokinases (HKs) are the enzymes that catalyses the ATP dependent phosphorylation of Hexose sugars to Hexose-6-Phosphate (Hex-6-P). There exist four different forms of HKs namely HK-I, HK-II, HK-III and HK-IV and all of them share a common ATP binding site core surrounded by more variable sequence that determine substrate affinities. Although they share a common binding site but they differ in their kinetic functions, hence the present study is aimed to analyze the binding mode of ATP. The analysis revealed that the four ATP binding domains are showing 13 identical, 7 similar and 6 dissimilar residues with similar structural conformation. Molecular docking of ATP into the kinase domains using Molecular Operating Environment (MOE) soft ware tool clearly showed the variation in the binding mode of ATP with variable docking scores. This probably explains the variable phosphorylation rates among hexokinases family. PMID:22829728

Kumar, Yellapu Nanda; Kumar, Pasupuleti Santhosh; Sowjenya, Gopal; Rao, Valasani Koteswara; Yeswanth, Sthanikam; Prasad, Uppu Venkateswara; Pradeepkiran, Jangampalli Adi; Sarma, PVGK; Bhaskar, Matcha

2012-01-01

16

Structure of ATP-Bound Human ATP:Cobalamin Adenosyltransferase  

SciTech Connect

Mutations in the gene encoding human ATP:cobalamin adenosyltransferase (hATR) can result in the metabolic disorder known as methylmalonic aciduria (MMA). This enzyme catalyzes the final step in the conversion of cyanocobalamin (vitamin B{sub 12}) to the essential human cofactor adenosylcobalamin. Here we present the 2.5 {angstrom} crystal structure of ATP bound to hATR refined to an R{sub free} value of 25.2%. The enzyme forms a tightly associated trimer, where the monomer comprises a five-helix bundle and the active sites lie on the subunit interfaces. Only two of the three active sites within the trimer contain the bound ATP substrate, thereby providing examples of apo- and substrate-bound-active sites within the same crystal structure. Comparison of the empty and occupied sites indicates that twenty residues at the enzyme's N-terminus become ordered upon binding of ATP to form a novel ATP-binding site and an extended cleft that likely binds cobalamin. The structure explains the role of 20 invariant residues; six are involved in ATP binding, including Arg190, which hydrogen bonds to ATP atoms on both sides of the scissile bond. Ten of the hydrogen bonds are required for structural stability, and four are in positions to interact with cobalamin. The structure also reveals how the point mutations that cause MMA are deficient in these functions.

Schubert,H.; Hill, C.

2006-01-01

17

Cervical anterior transpedicular screw fixation (ATPS)—Part II. Accuracy of manual insertion and pull-out strength of ATPS  

PubMed Central

Reconstruction after multilevel decompression of the cervical spine, especially in the weakened osteoporotic, neoplastic or infectious spine often requires circumferential stabilization and fusion. To avoid the additional posterior surgery in these cases while increasing rigidity of anterior-only screw-plate constructs, the authors introduce the concept of anterior transpedicular screw (ATPS) fixation. We demonstrated its morphological feasibility as well as its indications in a previous study in Part I of our project. Consequently, the objectives of the current study were to assess the ex vivo accuracy of placing ATPS into the cervical vertebra as well as the biomechanical performance of ATPS in comparison to traditional vertebral body screws (VBS) in terms of pull-out strength (POS). Twenty-three ATPS were inserted alternately to two screws into the pedicles and vertebral bodies, respectively, of six cadaveric specimens from C3–T1. For insertion of ATPS, a manual fluoroscopically assisted technique was used. Pre- and post insertional CT-scans were used to assess accuracy of ATPS insertion in the axial and sagittal planes. A newly designed grading system and accuracy score were used to delineate accuracy of ATPS insertion. Following insertion of screws, 23 ATPS and 22 VBS were subjected to pull-out testing (POT). The bone mineral density (BMD) of each specimen was assessed prior to POT. Statistical analysis showed that the incidence of correctly placed screws and non-critical pedicles breaches in axial plane was 78.3%, and 95.7% in sagittal plane. Hence, according to our definition of “critical” pedicle breach that exposes neurovascular structures at risk, 21.7% (n = 5) of all ATPS inserted showed a critical pedicle breach in axial plane. Notably, no critical pedicle perforation occurred at the C6 to T1 levels. Pull-out testing of ATPS and VBS revealed that pull-out resistance of ATPS was 2.5-fold that of VBS. Mean POS of 23 ATPS with a mean BMD of 0.566 g/cm2 and a mean osseus screw purchase of 27.2 mm was 467.8 N. In comparison, POS of 22 VBS screws with a mean BMD of 0.533 g/cm2 and a mean osseus screw purchase of 16.0 mm was 181.6 N. The difference in ultimate pull-out strength between the ATPS and VBS group was significant (p < 0.000001). Also, accuracy of ATPS placement in axial plane was shown to be significantly correlated with POS. In contrast, there was no correlation between screw-length, BMD, or level of insertion and the POS of ATPS or VBS. The study demonstrated that the use of ATPS might be a new technique worthy of further investigation. The use of ATPS shows the potential to increase construct rigidity in terms of screw-plate pull-out resistance. It might diminish construct failures during anterior-only reconstructions of the highly unstable decompressed cervical spine. Electronic supplementary material The online version of this article (doi:10.1007/s00586-007-0573-x) contains supplementary material, which is available to authorized users. PMID:18224357

Acosta, Frank; Tauber, Mark; Fox, Michael; Martin, Hudelmaier; Forstner, Rosmarie; Augat, Peter; Penzkofer, Rainer; Pirich, Christian; Kässmann, H.; Resch, Herbert; Hitzl, Wolfgang

2008-01-01

18

ATP-dependent Chromatin Remodelling  

Microsoft Academic Search

Alterations of chromatin structure play an important role in gene regulation. One way of doing so involves ATP-dependent chromatin\\u000a remodelling enzymes that act as molecular machines coupling ATP-hydrolysis to structural changes of the nucleosome. Several\\u000a recent studies shed important insights into the mechanism of these factors and indicate that they couple DNA translocation\\u000a within the nucleosome to DNA loop propagation

Parul Choudhary; Patrick Varga-Weisz

19

45 CFR 2510.20 - Definitions.  

Code of Federal Regulations, 2010 CFR

...OVERALL PURPOSES AND DEFINITIONS § 2510.20 Definitions. The following definitions apply to terms used...evaluations of a program or project). (iii) Costs...or an employee of a business of public or private...

2010-10-01

20

Implications of Recent Clinical Trials for the National Cholesterol Education Program Adult Treatment Panel III Guidelines  

Microsoft Academic Search

The Adult Treatment Panel III (ATP III) of the National Cholesterol Education Program issued an evidence-based set of guidelines on cholesterol management in 2001. Since the publication of ATP III, 5 major clinical trials of statin therapy with clinical end points have been published. These trials addressed issues that were not examined in previous clinical trials of cholesterol-lowering therapy. The

Scott M. Grundy; James I. Cleeman; C. Noel Bairey Merz; H. Bryan Brewer Jr; Luther T. Clark; Donald B. Hunninghake; Richard C. Pasternak; Sidney C. Smith Jr; Neil J. Stone

2004-01-01

21

Insulin-degrading enzyme hydrolyzes ATP.  

PubMed

We reported in a previous work that insulin degradation by insulin-degrading enzyme (IDE) was inhibited by ATP (Exp Biol Med 226:334-341, 2001). Then we studied ATP hydrolysis as a possible mechanism for reversion of this inhibition. ATP hydrolysis was determined by (32)P release after hydrolysis of gamma[(32)P]ATP. ATP hydrolysis was studied by Sephadex G200 chromatography, immunoprecipitation, and nondissociating gel electrophoresis. Purified recombinant rat IDE and extractive homogenous IDE showed similar ATP hydrolysis. All results showed concordance between insulin degradation and ATP hydrolysis, suggesting that IDE has both functions. In order to define the type of hydrolysis, we studied inhibitors of IDE, phosphohydrolases, and ATPases. Each substance studied had no effect on ATP hydrolysis, except 1 mM orthovanadate, a known inhibitor of ATPases, phosphatases, and insulin degradation. ATP hydrolysis followed a Michaelis-Menten kinetic with Vmax: 570.45 +/- 113.08 pmol Pi/hr and apparent Michaelis constant (Km): 63.13 +/- 3.48 microM. ATP binding studies strongly suggested an ATP binding site and enzyme kinetics established only one active hydrolytic ATP binding site per IDE molecule. ATP-induced enzyme aggregation changes as observed by electrophoresis mobility in nondissociating conditions and conformational changes on insulin binding as shown by IDE-insulin cross-linking. We conclude that IDEs have ATPase activity and that insulin-binding and degradation are dependent on ATP concentration; however, insulin does not modify the ATPase activity of IDE. PMID:17259336

Del Carmen Camberos, María; Cresto, Juan C

2007-02-01

22

Optimization of ATP synthase function in mitochondria and chloroplasts via the adenylate kinase equilibrium.  

PubMed

The bulk of ATP synthesis in plants is performed by ATP synthase, the main bioenergetics engine of cells, operating both in mitochondria and in chloroplasts. The reaction mechanism of ATP synthase has been studied in detail for over half a century; however, its optimal performance depends also on the steady delivery of ATP synthase substrates and the removal of its products. For mitochondrial ATP synthase, we analyze here the provision of stable conditions for (i) the supply of ADP and Mg(2+), supported by adenylate kinase (AK) equilibrium in the intermembrane space, (ii) the supply of phosphate via membrane transporter in symport with H(+), and (iii) the conditions of outflow of ATP by adenylate transporter carrying out the exchange of free adenylates. We also show that, in chloroplasts, AK equilibrates adenylates and governs Mg(2+) contents in the stroma, optimizing ATP synthase and Calvin cycle operation, and affecting the import of inorganic phosphate in exchange with triose phosphates. It is argued that chemiosmosis is not the sole component of ATP synthase performance, which also depends on AK-mediated equilibrium of adenylates and Mg(2+), adenylate transport, and phosphate release and supply. PMID:25674099

Igamberdiev, Abir U; Kleczkowski, Leszek A

2015-01-01

23

Optimization of ATP synthase function in mitochondria and chloroplasts via the adenylate kinase equilibrium  

PubMed Central

The bulk of ATP synthesis in plants is performed by ATP synthase, the main bioenergetics engine of cells, operating both in mitochondria and in chloroplasts. The reaction mechanism of ATP synthase has been studied in detail for over half a century; however, its optimal performance depends also on the steady delivery of ATP synthase substrates and the removal of its products. For mitochondrial ATP synthase, we analyze here the provision of stable conditions for (i) the supply of ADP and Mg2+, supported by adenylate kinase (AK) equilibrium in the intermembrane space, (ii) the supply of phosphate via membrane transporter in symport with H+, and (iii) the conditions of outflow of ATP by adenylate transporter carrying out the exchange of free adenylates. We also show that, in chloroplasts, AK equilibrates adenylates and governs Mg2+ contents in the stroma, optimizing ATP synthase and Calvin cycle operation, and affecting the import of inorganic phosphate in exchange with triose phosphates. It is argued that chemiosmosis is not the sole component of ATP synthase performance, which also depends on AK-mediated equilibrium of adenylates and Mg2+, adenylate transport, and phosphate release and supply. PMID:25674099

Igamberdiev, Abir U.; Kleczkowski, Leszek A.

2015-01-01

24

Impact of 4 different definitions used for the assessment of the prevalence of the Metabolic Syndrome in primary healthcare:The German Metabolic and Cardiovascular Risk Project (GEMCAS)  

PubMed Central

Background The metabolic syndrome (MetSyn) places individuals at increased risk for type 2 diabetes and cardiovascular disease. Prevalence rates of the population of the MetSyn are still scarce. Moreover, the impact of different definitions of the MetSyn on the prevalence is unclear. Aim here is to assess the prevalence of the MetSyn in primary health care and to investigate the impact of four different definitions of the MetSyn on the determined prevalence with regard to age, gender and socio-economic status. Methods The German-wide cross-sectional study was conducted during two weeks in October 2005 in 1.511 randomly selected general practices. Blood samples were analyzed, blood pressure and waist circumference assessed, data on lifestyle, medication, chronic disorders, and socio-demographic characteristics collected. MetSyn prevalence was estimated according to the definitions of NCEP ATP III (2001), AHA/NHLBI (2004, 2005), and IDF (2005). Descriptive statistics and prevalence rate ratios using the PROG GENMOD procedure, were calculated. Cohen's kappa was used as measure for interreliability between the different prevalence estimates. Results Data of 35,869 patients (age range: 18–99, women 61.1%) were included. The prevalence was lowest using the NCEP ATP III- (all: 19.8%, men 22.7%, women: 18.0%), highest according to the IDF-definition (32.7%, 40.3%, 28.0%). The increase in prevalence with recent definitions was more pronounced for men than for women, and was particularly high for men and women aged 60–79 years. The IDF-definition resulted in a higher prevalence especially in those with the highest educational status. Agreement (kappa) between the NCEP ATP III- and IDF-definition was 0.68 (men 0.61, women 0.74), between the updated the AHA/NHLBI- (2005) and IDF-definition 0.85 (men 0.79, women 0.89). Conclusion The prevalence of metabolic syndrome is associated with age, gender, and educational status and increases considerably with each newly published definition. Our data highlight the need for a better evidence regarding thresholds of the components of the metabolic syndrome, especially with regard to the IDF-definition – according to which in some populations a majority of subjects are diagnosed with the metabolic syndrome. PMID:17822558

Moebus, Susanne; Hanisch, Jens Ulrich; Aidelsburger, Pamela; Bramlage, Peter; Wasem, Jürgen; Jöckel, Karl-Heinz

2007-01-01

25

ATP-dependent DNA ligases  

Microsoft Academic Search

SUMMARY: By catalyzing the joining of breaks in the phosphodiester backbone of duplex DNA, DNA ligases play a vital role in the diverse processes of DNA replication, recombination and repair. Three related classes of ATP-dependent DNA ligase are readily apparent in eukaryotic cells. Enzymes of each class comprise catalytic and non-catalytic domains together with additional domains of varying function. DNA

Ina V Martin; Stuart A MacNeill

2002-01-01

26

Molecular phylogeny of the atpB and atpE genes of the brown alga Pylaiella littoralis  

Microsoft Academic Search

Recent phylogenetic studies suggest that plastid ribosomal RNA genes from Pylaiella littoralis have a cyanobacterial origin, whereas their Rubisco genes are related to the homologous ?- and ?- purple eubacterial genes. We have constructed a phylogenetic tree based upon the atpB and atpE sequences, including the same range of taxa (chlorophytes, chromophytes, cyanobacteria, ?- and ?-purple eubacteria) and using the

William F. Martin; Stefan Jouannic; Susan Loiseaux-De Goër

1993-01-01

27

Homeostasis of Extracellular ATP in Human Erythrocytes*  

PubMed Central

We explored the intra- and extracellular processes governing the kinetics of extracellular ATP (ATPe) in human erythrocytes stimulated with agents that increase cAMP. Using the luciferin-luciferase reaction in off-line luminometry we found both direct adenylyl cyclase activation by forskolin and indirect activation through ?-adrenergic stimulation with isoproterenol-enhanced [ATP]e in a concentration-dependent manner. A mixture (3V) containing a combination of these agents and the phosphodiesterase inhibitor papaverine activated ATP release, leading to a 3-fold increase in [ATP]e, and caused increases in cAMP concentration (3-fold for forskolin + papaverine, and 10-fold for 3V). The pannexin 1 inhibitor carbenoxolone and a pannexin 1 blocking peptide (10Panx1) decreased [ATP]e by 75–84%. The residual efflux of ATP resulted from unavoidable mechanical perturbations stimulating a novel, carbenoxolone-insensitive pathway. In real-time luminometry experiments using soluble luciferase, addition of 3V led to an acute increase in [ATP]e to a constant value of ?1 pmol × (106 cells)?1. A similar treatment using a surface attached luciferase (proA-luc) triggered a rapid accumulation of surface ATP levels to a peak concentration of 2.4 pmol × (106 cells)?1, followed by a slower exponential decay (t½ = 3.7 min) to a constant value of 1.3 pmol × (106 cells)?1. Both for soluble luciferase and proA-luc, ATP efflux was fully blocked by carbenoxolone, pointing to a 3V-induced mechanism of ATP release mediated by pannexin 1. Ecto-ATPase activity was extremely low (?28 fmol × (106 cells min)?1), but nevertheless physiologically relevant considering the high density of erythrocytes in human blood. PMID:21921036

Montalbetti, Nicolas; Leal Denis, Maria F.; Pignataro, Omar P.; Kobatake, Eiry; Lazarowski, Eduardo R.; Schwarzbaum, Pablo J.

2011-01-01

28

Evidence for an ATP-sensitive K+ channel in mitoplasts isolated from Trypanosoma cruzi and Crithidia fasciculata.  

PubMed

Mammalian mitochondria, as well as rat, plant and Caenorhabditis elegans mitochondria, possess an ATP-sensitive K+ channel (mitoK(ATP)) that has been pharmacologically characterised. Opening of mitoK(ATP) and the subsequent K+ entry into the matrix was shown to have three effects on mitochondria physiology: (i) an increase in matrix volume (swelling), (ii) an acceleration of respiration, and (iii) an increase in reactive oxygen species (ROS) production. These effects on mitochondria bioenergetics have been shown to be part of distinct intracellular signalling pathways, to protect against cell death and to modulate gene transcription. To date, such a channel or its activity has not been described in trypanosomatids. In the present study, we show pharmacological evidence for the presence of a mitoK(ATP) in trypanosomatids. Cells were incubated in a hypotonic medium followed by mild detergent exposure to isolate mitoplasts from Trypanosoma cruzi and Crithidia fasciculata. Mitoplasts swelled when incubated in KCl medium due to respiration-driven K+ entry into the matrix. Swelling was sensitive to the presence of ATP when the mitoplast suspension was incubated in K+ -containing, but not in K+ -free, medium. The ATP inhibition of swelling was reversed by the mitoK(ATP) agonist diazoxide and the diazoxide-induced swelling was inhibited by the mitoK(ATP) blockers 5-hydroxydecanoate (5HD) or glibenclamide. Similar to mammalian and rat mitochondria, trypanosomatid mitoK(ATP) activity was modulated by the general protein kinase C (PKC) agonist phorbol 12-myristate 13-acetate (PMA) and antagonist chelerythrine. As expected, the potassium ionophore valinomycin could also reverse the ATP-inhibited state but this reversal was not sensitive to 5HD or glibenclamide. Dose response curves for ATP, diazoxide and 5HD are presented. These results provide strong evidence for the presence of an ATP-sensitive K+ in trypanosomatid mitochondria. PMID:19504755

Costa, Alexandre D T; Krieger, Marco A

2009-07-15

29

Genetics Home Reference: Congenital disorder of glycosylation type IIi  

MedlinePLUS

... Recent literature OMIM Genetic disorder catalog Conditions > Congenital disorder of glycosylation type IIi On this page: Description Genetic changes ... Glossary definitions Reviewed August 2014 What is congenital disorder of glycosylation type IIi? Congenital disorder of glycosylation type IIi ( ...

30

How ATP Inhibits the Open KATP Channel  

PubMed Central

ATP-sensitive potassium (KATP) channels are composed of four pore-forming Kir6.2 subunits and four regulatory SUR1 subunits. Binding of ATP to Kir6.2 leads to inhibition of channel activity. Because there are four subunits and thus four ATP-binding sites, four binding events are possible. ATP binds to both the open and closed states of the channel and produces a decrease in the mean open time, a reduction in the mean burst duration, and an increase in the frequency and duration of the interburst closed states. Here, we investigate the mechanism of interaction of ATP with the open state of the channel by analyzing the single-channel kinetics of concatenated Kir6.2 tetramers containing from zero to four mutated Kir6.2 subunits that possess an impaired ATP-binding site. We show that the ATP-dependent decrease in the mean burst duration is well described by a Monod-Wyman-Changeux model in which channel closing is produced by all four subunits acting in a single concerted step. The data are inconsistent with a Hodgkin-Huxley model (four independent steps) or a dimer model (two independent dimers). When the channel is open, ATP binds to a single ATP-binding site with a dissociation constant of 300 ?M. PMID:18591420

Craig, Tim J.; Ashcroft, Frances M.; Proks, Peter

2008-01-01

31

Vesicular release of ATP at central synapses.  

PubMed

Adenosine triphosphate (ATP) acts as a fast excitatory transmitter in several regions of the central nervous system (CNS) including the medial habenula, dorsal horn, locus coeruleus, hippocampus, and somatosensory cortex. Postsynaptic actions of ATP are mediated through an extended family of P2X receptors, widely expressed throughout the CNS. ATP is released via several pathways, including exocytosis from presynaptic terminals and diffusion through large transmembrane pores (e.g., hemichannels, P2X(7) receptors, or volume-sensitive chloride channels) expressed in astroglial membranes. In presynaptic terminals, ATP is accumulated and stored in the synaptic vesicles. In different presynaptic terminals, these vesicles may contain ATP only or ATP and another neurotransmitter [e.g., gamma-amino-butyric acid (GABA) or glutamate]; in the latter case, two transmitters can be coreleased. Here, we discuss the mechanisms of vesicular release of ATP in the CNS and present our own data, which indicate that in central neuronal terminals, ATP is primarily stored and released from distinct pool of vesicles; the release of ATP is not synchronized either with GABA or with glutamate. PMID:16639550

Pankratov, Yuri; Lalo, Ulyana; Verkhratsky, Alexei; North, R Alan

2006-08-01

32

Conformational dynamics of ATP/Mg:ATP in motor proteins via data mining and molecular simulation  

NASA Astrophysics Data System (ADS)

The conformational diversity of ATP/Mg:ATP in motor proteins was investigated using molecular dynamics and data mining. Adenosine triphosphate (ATP) conformations were found to be constrained mostly by inter cavity motifs in the motor proteins. It is demonstrated that ATP favors extended conformations in the tight pockets of motor proteins such as F1-ATPase and actin whereas compact structures are favored in motor proteins such as RNA polymerase and DNA helicase. The incorporation of Mg2+ leads to increased flexibility of ATP molecules. The differences in the conformational dynamics of ATP/Mg:ATP in various motor proteins was quantified by the radius of gyration. The relationship between the simulation results and those obtained by data mining of motor proteins available in the protein data bank is analyzed. The data mining analysis of motor proteins supports the conformational diversity of the phosphate group of ATP obtained computationally.

Bojovschi, A.; Liu, Ming S.; Sadus, Richard J.

2012-08-01

33

Pyrazinoic Acid Decreases the Proton Motive Force, Respiratory ATP Synthesis Activity, and Cellular ATP Levels?†  

PubMed Central

Pyrazinoic acid, the active form of the first-line antituberculosis drug pyrazinamide, decreased the proton motive force and respiratory ATP synthesis rates in subcellular mycobacterial membrane assays. Pyrazinoic acid also significantly lowered cellular ATP levels in Mycobacterium bovis BCG. These results indicate that the predominant mechanism of killing by this drug may operate by depletion of cellular ATP reserves. PMID:21876062

Lu, Ping; Haagsma, Anna C.; Pham, Hoang; Maaskant, Janneke J.; Mol, Selena; Lill, Holger; Bald, Dirk

2011-01-01

34

Catalytic strategy used by the myosin motor to hydrolyze ATP  

PubMed Central

Myosin is a molecular motor responsible for biological motions such as muscle contraction and intracellular cargo transport, for which it hydrolyzes adenosine 5'-triphosphate (ATP). Early steps of the mechanism by which myosin catalyzes ATP hydrolysis have been investigated, but still missing are the structure of the final ADP·inorganic phosphate (Pi) product and the complete pathway leading to it. Here, a comprehensive description of the catalytic strategy of myosin is formulated, based on combined quantum–classical molecular mechanics calculations. A full exploration of catalytic pathways was performed and a final product structure was found that is consistent with all experiments. Molecular movies of the relevant pathways show the different reorganizations of the H-bond network that lead to the final product, whose ?-phosphate is not in the previously reported HP?O42? state, but in the H2P?O4? state. The simulations reveal that the catalytic strategy of myosin employs a three-pronged tactic: (i) Stabilization of the ?-phosphate of ATP in a dissociated metaphosphate (P?O3?) state. (ii) Polarization of the attacking water molecule, to abstract a proton from that water. (iii) Formation of multiple proton wires in the active site, for efficient transfer of the abstracted proton to various product precursors. The specific role played in this strategy by each of the three loops enclosing ATP is identified unambiguously. It explains how the precise timing of the ATPase activation during the force generating cycle is achieved in myosin. The catalytic strategy described here for myosin is likely to be very similar in most nucleotide hydrolyzing enzymes. PMID:25006262

Kiani, Farooq Ahmad; Fischer, Stefan

2014-01-01

35

77 FR 40478 - Removal of Category IIIa, IIIb, and IIIc Definitions; Confirmation of Effective Date and Response...  

Federal Register 2010, 2011, 2012, 2013, 2014

...certification or operational authorization. Removing the definitions will aid in...and IIIc definitions. The Category III operational concepts represented...and IIIc definitions in its development...Category III operational...

2012-07-10

36

77 FR 39388 - Removal of Category IIIa, IIIb, and IIIc Definitions; Confirmation of Effective Date and Response...  

Federal Register 2010, 2011, 2012, 2013, 2014

...certification or operational authorization. Removing the definitions will aid in...and IIIc definitions. The Category III operational concepts represented...and IIIc definitions in its development...Category III operational...

2012-07-03

37

January 2007 Economic Impact of ATP's  

E-print Network

Alan O'Connor, Brent Rowe, Michael Gallaher Joel Sevinsky, and Dallas Wood #12;About ATP's Economic of Joint Ventures. · Status Reports, mini case studies that assess ATP projects on several years after Michael Gallaher Joel Sevinsky Dallas Wood RTI International Research Triangle Park, NC oconnor

38

ATP2B4/A0114  

NSDL National Science Digital Library

Plasma membrane calcium-transporting ATPase 4 (ATP2B4), also known as A0114, is a multi-pass membrane protein, which catalyzes the hydrolysis of adenosine triphosphate (ATP) coupled with the transport of calcium out of the cell.

2009-04-14

39

ATP-triggered anticancer drug delivery  

NASA Astrophysics Data System (ADS)

Stimuli-triggered drug delivery systems have been increasingly used to promote physiological specificity and on-demand therapeutic efficacy of anticancer drugs. Here we utilize adenosine-5'-triphosphate (ATP) as a trigger for the controlled release of anticancer drugs. We demonstrate that polymeric nanocarriers functionalized with an ATP-binding aptamer-incorporated DNA motif can selectively release the intercalating doxorubicin via a conformational switch when in an ATP-rich environment. The half-maximal inhibitory concentration of ATP-responsive nanovehicles is 0.24??M in MDA-MB-231 cells, a 3.6-fold increase in the cytotoxicity compared with that of non-ATP-responsive nanovehicles. Equipped with an outer shell crosslinked by hyaluronic acid, a specific tumour-targeting ligand, the ATP-responsive nanocarriers present an improvement in the chemotherapeutic inhibition of tumour growth using xenograft MDA-MB-231 tumour-bearing mice. This ATP-triggered drug release system provides a more sophisticated drug delivery system, which can differentiate ATP levels to facilitate the selective release of drugs.

Mo, Ran; Jiang, Tianyue; Disanto, Rocco; Tai, Wanyi; Gu, Zhen

2014-03-01

40

Historical review: ATP as a neurotransmitter  

E-print Network

signalling is now recognized to be involved in a wide range of activities of the nervous system, including of a transmitter role for ATP in the nervous system by demonstrating the release of ATP during antidromic stimulation of sensory nerves supplying the rabbit ear artery [5]. Buchthal and Folkow recognized a physiologi

Burnstock, Geoffrey

41

Open State Destabilization by ATP Occupancy Is Mechanism Speeding Burst Exit Underlying KATP Channel Inhibition by ATP  

Microsoft Academic Search

The ATP-sensitive potassium (K ATP ) channel is named after its characteristic inhibition by intracellular ATP. The inhibition is a centerpiece of how the K ATP channel sets electrical signaling to the energy state of the cell. In thecell of the endocrine pancreas, for example, ATP inhibition results from high blood glucose levels and turns on electrical activity leading to

Lehong Li; Xuehui Geng; Peter Drain

2002-01-01

42

The ADP/ATP Carrier and Its Relationship to Oxidative Phosphorylation in Ancestral Protist Trypanosoma brucei.  

PubMed

The highly conserved ADP/ATP carrier (AAC) is a key energetic link between the mitochondrial (mt) and cytosolic compartments of all aerobic eukaryotic cells, as it exchanges the ATP generated inside the organelle for the cytosolic ADP. Trypanosoma brucei, a parasitic protist of medical and veterinary importance, possesses a single functional AAC protein (TbAAC) that is related to the human and yeast ADP/ATP carriers. However, unlike previous studies performed with these model organisms, this study showed that TbAAC is most likely not a stable component of either the respiratory supercomplex III+IV or the ATP synthasome but rather functions as a physically separate entity in this highly diverged eukaryote. Therefore, TbAAC RNA interference (RNAi) ablation in the insect stage of T. brucei does not impair the activity or arrangement of the respiratory chain complexes. Nevertheless, RNAi silencing of TbAAC caused a severe growth defect that coincides with a significant reduction of mt ATP synthesis by both substrate and oxidative phosphorylation. Furthermore, TbAAC downregulation resulted in a decreased level of cytosolic ATP, a higher mt membrane potential, an elevated amount of reactive oxygen species, and a reduced consumption of oxygen in the mitochondria. Interestingly, while TbAAC has previously been demonstrated to serve as the sole ADP/ATP carrier for ADP influx into the mitochondria, our data suggest that a second carrier for ATP influx may be present and active in the T. brucei mitochondrion. Overall, this study provides more insight into the delicate balance of the functional relationship between TbAAC and the oxidative phosphorylation (OXPHOS) pathway in an early diverged eukaryote. PMID:25616281

Gnipová, Anna; Šubrtová, Karolína; Panicucci, Brian; Horváth, Anton; Lukeš, Julius; Zíková, Alena

2015-03-01

43

75 FR 25294 - Notice Pursuant to the National Cooperative Research and Production Act of 1993-High Definition...  

Federal Register 2010, 2011, 2012, 2013, 2014

...Definition Metrology and Process-2 Micron Manufacturing Under ATP Award No. 70NANB77041 Notice is hereby given that, on March...Definition Metrology and Process-2 Micron Manufacturing under ATP Award No. 70NANB7H7041 has filed written notifications...

2010-05-07

44

Communication Definitions... general definition  

E-print Network

Communication Definitions... general definition "the process of conveying information from a sender to a receiver with the use of a medium in which the communicated information is understood the same way by both sender and receiver" (Wikipedia)! Biological communication Action by one organism (individual

Jones, Ian L.

45

Cryopyrin/NALP3 binds ATP/dATP, is an ATPase, and requires ATP binding to mediate inflammatory signaling  

PubMed Central

The CATERPILLER (CLR/NLR) gene family encodes a family of putative nucleotide-binding proteins important for host defense. Although nucleotide binding is thought to be central to this family, this aspect is largely unstudied. The CATERPILLER protein cryopyrin/NALP3 regulates IL-1? processing by assembling the multimeric inflammasome complex. Mutations within the exon encoding the nucleotide-binding domain are associated with hereditary periodic fevers characterized by constitutive IL-1? production. We demonstrate that purified cryopyrin binds ATP, dATP, and ATP-agarose, but not CTP, GTP, or UTP, and exhibits ATPase activity. Mutation of the nucleotide-binding domain reduces ATP binding, caspase-1 activation, IL-1? production, cell death, macromolecular complex formation, self-association, and association with the inflammasome component ASC. Disruption of nucleotide binding abolishes the constitutive activation of disease-associated mutants, identifying nucleotide binding by cryopyrin as a potential target for antiinflammatory pharmacologic intervention. PMID:17483456

Duncan, Joseph A.; Bergstralh, Daniel T.; Wang, Yanhong; Willingham, Stephen B.; Ye, Zhengmao; Zimmermann, Albert G.; Ting, Jenny Pan-Yun

2007-01-01

46

ATP-dependent nucleosome remodeling.  

PubMed

It has been a long-standing challenge to decipher the principles that enable cells to both organize their genomes into compact chromatin and ensure that the genetic information remains accessible to regulatory factors and enzymes within the confines of the nucleus. The discovery of nucleosome remodeling activities that utilize the energy of ATP to render nucleosomal DNA accessible has been a great leap forward. In vitro, these enzymes weaken the tight wrapping of DNA around the histone octamers, thereby facilitating the sliding of histone octamers to neighboring DNA segments, their displacement to unlinked DNA, and the accumulation of patches of accessible DNA on the surface of nucleosomes. It is presumed that the collective action of these enzymes endows chromatin with dynamic properties that govern all nuclear functions dealing with chromatin as a substrate. The diverse set of ATPases that qualify as the molecular motors of the nucleosome remodeling process have a common history and are part of a superfamily. The physiological context of their remodeling action builds on the association with a wide range of other proteins to form distinct complexes for nucleosome remodeling. This review summarizes the recent progress in our understanding of the mechanisms underlying the nucleosome remodeling reaction, the targeting of remodeling machines to selected sites in chromatin, and their integration into complex regulatory schemes. PMID:12045097

Becker, Peter B; Hörz, Wolfram

2002-01-01

47

Alternative proton binding mode in ATP synthases.  

PubMed

ATP synthases are rotary engines which use the energy stored in a transmembrane electrochemical gradient of protons or sodium ions to catalyze the formation of ATP by ADP and inorganic phosphate. Current models predict that protonation/deprotonation of specific amino acids of the rotating c-ring, extracting protons from one side and delivering them to the other side of the membrane, are at the core of the proton translocation mechanism of these enzymes. In this minireview, an alternative proton binding mechanism is presented, considering hydronium ion coordination as proposed earlier. Biochemical data and structural considerations provide evidence for two different proton binding modes in the c-ring of H+-translocating ATP synthases. Recent investigations in several other proton translocating membrane proteins suggest, that hydronium ion coordination by proteins might display a general principle which was so far underestimated in ATP synthases. PMID:17965925

von Ballmoos, Christoph

2007-12-01

48

An RNA motif that binds ATP  

NASA Technical Reports Server (NTRS)

RNAs that contain specific high-affinity binding sites for small molecule ligands immobilized on a solid support are present at a frequency of roughly one in 10(10)-10(11) in pools of random sequence RNA molecules. Here we describe a new in vitro selection procedure designed to ensure the isolation of RNAs that bind the ligand of interest in solution as well as on a solid support. We have used this method to isolate a remarkably small RNA motif that binds ATP, a substrate in numerous biological reactions and the universal biological high-energy intermediate. The selected ATP-binding RNAs contain a consensus sequence, embedded in a common secondary structure. The binding properties of ATP analogues and modified RNAs show that the binding interaction is characterized by a large number of close contacts between the ATP and RNA, and by a change in the conformation of the RNA.

Sassanfar, M.; Szostak, J. W.

1993-01-01

49

Customized ATP towpreg. [Automated Tow Placement  

NASA Technical Reports Server (NTRS)

Automated tow placement (ATP) utilizes robotic technology to lay down adjacent polymer-matrix-impregnated carbon fiber tows on a tool surface. Consolidation and cure during ATP requires that void elimination and polymer matrix adhesion be accomplished in the short period of heating and pressure rolling that follows towpreg ribbon placement from the robot head to the tool. This study examined the key towpreg ribbon properties and dimensions which play a significant role in ATP. Analysis of the heat transfer process window indicates that adequate heating can be achieved at lay down rates as high as 1 m/sec. While heat transfer did not appear to be the limiting factor, resin flow and fiber movement into tow lap gaps could be. Accordingly, consideration was given to towpreg ribbon having uniform yet non-rectangular cross sections. Dimensional integrity of the towpreg ribbon combined with customized ribbon architecture offer great promise for processing advances in ATP of high performance composites.

Sandusky, Donald A.; Marchello, Joseph M.; Baucom, Robert M.; Johnston, Norman J.

1992-01-01

50

ATP1A1/A0340  

NSDL National Science Digital Library

Sodium/potassium-transporting ATPase alpha-1 subunit (ATP1A1, also known as A0340) is an isoform of the catalytic subunit of the three subunit cation transporting pump, sodium/potassium-transporting ATPase.

2009-04-14

51

Extracellular ATP is internalized by macropinocytosis and induces intracellular ATP increase and drug resistance in cancer cells.  

PubMed

ATP plays central roles in cancer metabolism and the Warburg effect. Intratumoral ATP concentrations are up to 10(4) times higher than those of interstitial ATP in normal tissues. However, extracellular ATP is not known to enter cancer cells. Here we report that human A549 lung cancer cells internalized extracellular ATP by macropinocytosis as demonstrated by colocalization of a nonhydrolyzable fluorescent ATP and a macropinocytosis tracer high-molecular-weight dextran, as well as by a macropinocytosis inhibitor study. Extracellular ATP also induced increase of intracellular ATP levels, without involving transcription and translation at significant levels, and cancer cells' resistance to ATP-competitor anticancer drugs, likely through the mechanism of ATP internalization. These findings, described for the first time, have profound implications in ATP-sharing among cancer cells in tumors and highlight a novel anticancer target. PMID:24973521

Qian, Yanrong; Wang, Xuan; Liu, Yi; Li, Yunsheng; Colvin, Robert A; Tong, Lingying; Wu, Shiyong; Chen, Xiaozhuo

2014-09-01

52

Mitochondrial ATP synthase: architecture, function and pathology  

Microsoft Academic Search

Human mitochondrial (mt) ATP synthase, or complex V consists of two functional domains: F1, situated in the mitochondrial matrix, and Fo, located in the inner mitochondrial membrane. Complex V uses the energy created by the proton electrochemical gradient to\\u000a phosphorylate ADP to ATP. This review covers the architecture, function and assembly of complex V. The role of complex V di-and

An I. Jonckheere; Jan A. M. Smeitink; Richard J. T. Rodenburg

53

The ATP Synthase atpHAGDC (F1) Operon from Rhodobacter capsulatus  

PubMed Central

The atpHAGDC operon of Rhodobacter capsulatus, containing the five genes coding for the F1 sector of the ATP synthase, has been cloned and sequenced. The promoter region has been defined by primer extension analysis. It was not possible to obtain viable cells carrying atp deletions in the R. capsulatus chromosome, indicating that genes coding for ATP synthase are essential, at least under the growth conditions tested. We were able to circumvent this problem by combining gene transfer agent transduction with conjugation. This method represents an easy way to construct strains carrying mutations in indispensable genes. PMID:9440534

Borghese, Roberto; Crimi, Massimo; Fava, Luca; Melandri, Bruno Andrea

1998-01-01

54

ACRIM III  

Atmospheric Science Data Center

... ACRIM III Data and Information Active Cavity Radiometer Irradiance Monitor ( ACRIM ) III monitors the total variability of solar irradiance with active cavity radiometer solar monitoring sensors. ACRIM III was successfully launched on ...

2014-08-08

55

SAGE III  

Atmospheric Science Data Center

SAGE III Data and Information The Stratospheric Aerosol and Gas ... Guide Documents:  Project Guide Data Products User's Guide  (PDF) Relevant Documents:  ... Join SAGE III News List SAGE I Data Table SAGE II Data Table SAGE III Home Page ...

2014-12-04

56

ATP Synthesis in the Extremely Halophilic Bacteria  

NASA Technical Reports Server (NTRS)

The proton-translocating ATPases are multimeric enzymes that carry out a multitude of essential functions. Their origin and evolution represent a seminal event in the early evolution of life. Amino acid sequences of the two largest subunits from archaeal ATPases (A-ATPases), vacuolar ATPases (V-ATPases), and FOF1-ATP syntheses (FATPases) suggest these ATPases evolved from an ancestral vacuolar-like ATP syntheses. A necessary consequence of this notion is that the A-ATPases are ATP syntheses. With the possible exception of the A-ATPase from Halobacterium salinarium. no A-ATPase has been demonstrated to synthesize ATP. The evidence for this case is dubious since ATP synthesis occurs only when conditions are distinctively unphysiological. We demonstrated that ATP synthesis in H.saccharovorum is inconsistent with the operation of an A-type ATPase. In order to determine if this phenomenon was unique to H. saccharovorum, ATP synthesis was examined in various extremely halophilic bacteria with the goal of ascertaining if it resembled what occurred in a. saccharovorum, or was consistent with the operation of an A-type ATPase. A-, V-, and F-type ATPases respond singularly to certain inhibitors. Therefore, the effect of these inhibitors on ATP synthesis in several extreme halophiles was determined. Inhibitors that either blocked or collapsed proton-gradients inhibited the steady state synthesis of ATP thus verifying that synthesis took place at the expense of a proton gradient. Azide, an inhibitor of F-ATPases inhibited ATP synthesis. Since the arginine-dependent synthesis of ATP, which occurs by way of substrate-level phosphorylation, was unaffected by azide, it was unlikely that azide acted as an "uncoupler." N -ethylmaleimide and nitrate, which inhibit V- and A-ATPases, either did not inhibit ATP synthesis or resulted in higher steady-state levels of ATP. These results suggest there are two types of proton-motive ATPases in the extreme halophiles (and presumably in other Archaea). One, the V-like enzyme which, provides protons that are subsequently used for solute translocation. The other ATPase is the familiar and ubiquitous F-ATPase that functions as a reversible proton pump and is the ATP Synthase in the extreme halophiles. Thus, while the suggested evolution of the proton -translocating ATPases accounts for the relationship among these ATPases, this scheme does not account for the presence of F-ATPases in the Archaea. Discounting lateral gene transfer, perhaps an F-type ATPase evolved before the eucaryal-archaeal and bacterial bifurcation. The presence of V-type ATPases in the Bacterial Domain is consistent with this suggestion. Finally, it is of interest to note that if an F-type ATPase appeared before the bifurcation, an endosymbiotic event need not be invoked to explain the presence of F-ATPases in the Eucarya.

Hochstein, Lawrence I.; Morrison, David (Technical Monitor)

1994-01-01

57

ATP, GLIA and CENTRAL RESPIRATORY CONTROL  

PubMed Central

An increase in PCO2 in the arterial blood triggers immediate release of ATP from the ventral chemosensory site(s) on the surface of the medulla oblongata. Systemic hypoxia in anesthetized rats was also associated with increased ATP release on the ventral medullary surface. During both hypoxia and hypercapnia, ATP and possibly other gliotransmitters released in the ventral medulla seemed to enhance cardiorespiratory responses to these stressors, and some of this ATP was proposed to be derived from astrocytes. Astrocytes also play a vital role controlling local blood flow. Astrocytes are activated by neurotransmitter release - especially glutamate and ATP. The astrocytic activation is manifest as a rise in intracellular Ca2+ that is closely coupled to the metabolic activity of neurons in the active area. The activation of astrocytes spreads as a wave from astrocyte to astrocyte and causes release of ATP, adenosine, and other gliotransmitters that may alter neuronal function in the region of astrocytic activation. In addition, ATP, adenosine and other vasoactive substances, when released at the endfeet of astrocytes, interact with vascular receptors that may either dilate or constrict the vessels in the region closely adjacent to the site of neuronal activity. Thus, astrocytes seem to integrate neuronal metabolic needs by responding to the level of neuronal activity to regulate local blood flow and cardiorespiratory responses to hypoxia and hypercapnia to match substrate need (oxygen and glucose) with substrate availability and with the removal of CO2. In so doing, astrocytes assume a larger role in information processing and in the regulation of neuronal activity and homeostasis of the entire organism than has been ascribed to them in the past. PMID:20601205

Erlichman, Joseph S.; Leiter, J.C.; Gourine, Alexander V.

2010-01-01

58

Voltage Dependence of ATP Secretion in Mammalian Taste Cells  

PubMed Central

Mammalian type II taste cells release the afferent neurotransmitter adenosine triphosphate (ATP) through ATP-permeable ion channels, most likely to be connexin (Cx) and/or pannexin hemichannels. Here, we show that ion channels responsible for voltage-gated (VG) outward currents in type II cells are ATP permeable and demonstrate a strong correlation between the magnitude of the VG current and the intensity of ATP release. These findings suggest that slowly deactivating ion channels transporting the VG outward currents can also mediate ATP secretion in type II cells. In line with this inference, we studied a dependence of ATP secretion on membrane voltage with a cellular ATP sensor using different pulse protocols. These were designed on the basis of predictions of a model of voltage-dependent transient ATP efflux. Consistently with curves that were simulated for ATP release mediated by ATP-permeable channels deactivating slowly, the bell-like and Langmuir isotherm–like potential dependencies were characteristic of ATP secretion obtained for prolonged and short electrical stimulations of taste cells, respectively. These observations strongly support the idea that ATP is primarily released via slowly deactivating channels. Depolarizing voltage pulses produced negligible Ca2+ transients in the cytoplasm of cells releasing ATP, suggesting that ATP secretion is mainly governed by membrane voltage under our recording conditions. With the proviso that natural connexons and pannexons are kinetically similar to exogenously expressed hemichannels, our findings suggest that VG ATP release in type II cells is primarily mediated by Cx hemichannels. PMID:19029378

Romanov, Roman A.; Rogachevskaja, Olga A.; Khokhlov, Alexander A.; Kolesnikov, Stanislav S.

2008-01-01

59

Assembly of the rotor component of yeast mitochondrial ATP synthase is enhanced when Atp9p is supplied by Atp9p-Cox6p complexes.  

PubMed

The Atp9p ring is one of several assembly modules of yeast mitochondrial ATP synthase. The ring, composed of 10 copies of Atp9p, is part of the rotor that couples proton translocation to synthesis or hydrolysis of ATP. We present evidence that before its assembly with other ATP synthase modules, most of Atp9p is present in at least three complexes with masses of 200-400 kDa that co-immunopurify with Cox6p. Pulse-labeling analysis disclosed a time-dependent reduction of radiolabeled Atp9p in the complexes and an increase of Atp9p in the ring form of wild type yeast and of mss51, pet111, and pet494 mutants lacking Cox1p, Cox2p, and Cox3p, respectively. Ring formation was not significantly different from wild type in an mss51 or atp10 mutant. The atp10 mutation blocks the interaction of the Atp9p ring with other modules of the ATP synthase. In contrast, ring formation was reduced in a cox6 mutant, consistent with a role of Cox6p in oligomerization of Atp9p. Cox6p involvement in ATP synthase assembly is also supported by studies showing that ring formation in cells adapting from fermentative to aerobic growth was less efficient in mitochondria of the cox6 mutant than the parental respiratory-competent strain or a cox4 mutant. We speculate that the constitutive and Cox6p-independent rate of Atp9p oligomerization may be sufficient to produce the level of ATP synthase needed for maintaining a membrane potential but limiting for optimal oxidative phosphorylation. PMID:25253699

Su, Chen-Hsien; McStay, Gavin P; Tzagoloff, Alexander

2014-11-01

60

Sulfide-based ATP production in Urechis unicinctus  

NASA Astrophysics Data System (ADS)

We measured sulfide-based ATP production by isolated mitochondria from four tissues of Urechis unicinctus and the effects of inhibitors of respiratory complexes on ATP production were evaluated. The results show that these mitochondria could oxidize sulfide to produce ATP. The yield of sulfide-stimulated ATP varied from 5 nmol ATP/min/mg to 90 nmol ATP/min/mg according to the sulfide concentration and the source of the mitochondria. The maximum ATP synthesis occurred in hindgut mitochondria using 5 ?mol/L sulfide as a substrate. The effects of inhibitors (Rotenone, Antimycin A, Cyanide, and Salicylhydroxamic acid) on mitochondrial ATP production varied with the source of the mitochondria. Our results indicate that sulfide-based ATP production and the associated electron transport pathway are tissue-specific in U. unicinctus.

Ma, Zhuojun; Bao, Zhenmin; Wang, Sifeng; Zhang, Zhifeng

2010-05-01

61

The Structural Basis of ATP as an Allosteric Modulator  

PubMed Central

Adenosine-5’-triphosphate (ATP) is generally regarded as a substrate for energy currency and protein modification. Recent findings uncovered the allosteric function of ATP in cellular signal transduction but little is understood about this critical behavior of ATP. Through extensive analysis of ATP in solution and proteins, we found that the free ATP can exist in the compact and extended conformations in solution, and the two different conformational characteristics may be responsible for ATP to exert distinct biological functions: ATP molecules adopt both compact and extended conformations in the allosteric binding sites but conserve extended conformations in the substrate binding sites. Nudged elastic band simulations unveiled the distinct dynamic processes of ATP binding to the corresponding allosteric and substrate binding sites of uridine monophosphate kinase, and suggested that in solution ATP preferentially binds to the substrate binding sites of proteins. When the ATP molecules occupy the allosteric binding sites, the allosteric trigger from ATP to fuel allosteric communication between allosteric and functional sites is stemmed mainly from the triphosphate part of ATP, with a small number from the adenine part of ATP. Taken together, our results provide overall understanding of ATP allosteric functions responsible for regulation in biological systems. PMID:25211773

Wang, Qi; Shen, Qiancheng; Li, Shuai; Nussinov, Ruth; Zhang, Jian

2014-01-01

62

Comparative features of copper ATPases ATP7A and ATP7B heterologously expressed in COS-1 cells.  

PubMed

ATP7A and ATP7B are P-type ATPases required for copper homeostasis and involved in the etiology of Menkes and Wilson diseases. We used heterologous expression of ATP7A or ATP7B in COS-1 cells infected with adenovirus vectors to characterize differential features pertinent to each protein expressed in the same mammalian cell type, rather than to extrinsic factors related to different cells sustaining expression. Electrophoretic analysis of the expressed protein, before and after purification, prior or subsequent to treatment with endoglycosidase, and evidenced by protein or glycoprotein staining as well as Western blotting, indicates that the ATP7A protein is glycosylated while ATP7B is not. This is consistent with the prevalence of glycosylation motifs in the ATP7A sequence, and not in ATP7B. ATP7A and ATP7B undergo copper-dependent phosphorylation by utilization of ATP, forming equal levels of an "alkali labile" phosphoenzyme intermediate that undergoes similar catalytic (P-type ATPase) turnover in both enzymes. In addition, incubation with ATP yields an "alkali stable" phosphoprotein fraction, attributed to phosphorylation of serines. Alkali stable phosphorylation occurs at lower levels in ATP7A, consistent with a different distribution of serines in the amino acid sequence. Immunostaining of COS-1 cells sustaining heterologous expression shows initial association of both ATP7A and ATP7B with Golgi and the trans-Golgi network. However, in the presence of added copper, ATP7A undergoes prevalent association with the plasma membrane while ATP7B exhibits intense trafficking with cytosolic vesicles. Glycosylation of ATP7A and phosphorylation of ATP7B apparently contribute to their different trafficking and membrane association when expressed in the same cell type. PMID:20964302

Liu, Yueyong; Pilankatta, Rajendra; Hatori, Yuta; Lewis, David; Inesi, Giuseppe

2010-11-23

63

77 FR 39626 - Further Definition of “Swap Dealer,” “Security-Based Swap Dealer,” “Major Swap Participant...  

Federal Register 2010, 2011, 2012, 2013, 2014

...in the third column, correct paragraph (hhh)(6)(iii)(B)(2) to read as follows: Sec. 1.3 Definitions. * * * * * (hhh) * * * (6) * * * (iii) * * * (B...the amount calculated under paragraph (hhh)(6)(iii)(B)(1) of this...

2012-07-05

64

A reusable prepositioned ATP reaction chamber  

NASA Technical Reports Server (NTRS)

Luminescence biometer detects presence of life by means of light-emitting chemical reaction of luciferin and luciferase with adenosine triphosphate (ATP) that occurs in all living cells. Amount of light in reaction chamber is measured to determine presence and extent of life.

Hoffman, D. G.

1972-01-01

65

Mitochondrial DNA & Oxidative Phosphorylation ATP SYNTHASE  

E-print Network

Mitochondrial DNA & Oxidative Phosphorylation 2 proteins ATP SYNTHASE COMPLEX IV COMPLEX IIICOMPLEX II COMPLEX I 1 protein 3 proteins Human mitochondrial DNA 7 proteins #12;Replication Organisation Segregation The mtDNA Troika #12;Replication Organisation Segregation The mtDNA Troika #12;Mitochondrial (DNA

Schnaufer, Achim

66

Monitoring enzymatic ATP hydrolysis by EPR spectroscopy.  

PubMed

An adenosine triphosphate (ATP) analogue modified with two nitroxide radicals is developed and employed to study its enzymatic hydrolysis by electron paramagnetic resonance spectroscopy. For this application, we demonstrate that EPR holds the potential to complement fluorogenic substrate analogues in monitoring enzymatic activity. PMID:24872080

Hacker, Stephan M; Hintze, Christian; Marx, Andreas; Drescher, Malte

2014-07-14

67

Kinetics of extracellular ATP in mastoparan 7-activated human erythrocytes  

PubMed Central

SUMMARY Background The peptide mastoparan 7 (MST7) stimulated ATP release in human erythrocytes. We explored intra- and extracellular processes governing the time-dependent accumulation of extracellular ATP (i.e., ATPe kinetics). Methods Human erythrocytes were treated with MST7 in the presence or absence of two blockers of pannexin 1. ATPe concentration was monitored by luciferin-luciferase based real-time luminometry. Results Exposure of human erythrocytes to MST7 led to an acute increase in [ATPe], followed by a slower increase phase. ATPe kinetics reflected a strong activation of ATP efflux and a low rate of ATPe hydrolysis by ectoATPase activity. Enhancement of [ATPe] by MST7 required adhesion of erythrocytes to poly-D-lysin-coated coverslips, and correlated with a 31% increase of cAMP and 10% cell swelling. However, when MST7 was dissolved in a hyperosmotic medium to block cell swelling, ATPe accumulation was inhibited by 49%. Erythrocytes pre-exposure to 10 ?M of either carbenoxolone or probenecid, two blockers of pannexin 1, exhibited a partial reduction of ATP efflux. Erythrocytes from pannexin 1 knockout mice exhibited similar ATPe kinetics as those of wild type mice erythrocytes exposed to pannexin 1 blockers. Conclusions MST7 induced release of ATP required either cell adhesion or strong activation of cAMP synthesis. Part of this release required cell swelling. Kinetic analysis and a data driven model suggested that ATP efflux is mediated by two ATP conduits displaying different kinetics, with one conduit being fully blocked by pannexin 1 blockers. General Significance Kinetic analysis of extracellular ATP accumulation from human erythrocytes and potential effects on microcirculation. PMID:23742824

Denis, María Florencia Leal; Incicco, J. Jeremías; Espelt, María Victoria; Verstraeten, Sandra V.; Pignataro, Omar P.; Lazarowski, Eduardo R.; Schwarzbaum, Pablo J.

2014-01-01

68

ATP levels and glutathione regeneration in canine erythrocytes  

Microsoft Academic Search

The effect of ATP levels on GSH regeneration was examined in canine erythrocytes. The main findings were: (1) The GSH regeneration\\u000a was dependent on glucose and ATP; (2) cytochalasin B and polymyxin B, both glucose transport inhibitors, reduced ATP synthesis\\u000a and GSH regeneration; (3) inosine, a substrate of the salvage pathway, was not effective for ATP synthesis and GSH regeneration.

M. Suzuki; M. Abe; M. Kurata; N. S. Agar

1997-01-01

69

Renal Cell-to-Cell Communication via Extracellular ATP  

NSDL National Science Digital Library

In the kidney, macula densa cells communicate with the mesangial cell-afferent arteriolar smooth muscle cell complex through ATP signaling. This signaling process involves release of ATP across the macula densa basolateral membrane through a maxi anion channel and the interaction of ATP with purinergic P2 receptors.

MD Peter Komlosi (University of Alabama at Birmingham Departments of Medicine and Physiology, Division of Nephrology)

2005-04-01

70

Physiological levels of ATP Negatively Regulate Proteasome Function  

PubMed Central

Intracellular protein degradation by the ubiquitin-proteasome system is ATP-dependent and the optimal ATP concentration to activate proteasome function in vitro is ~100 ?M. Intracellular ATP levels are generally in the low millimolar range but ATP at a level within this range was shown to inhibit proteasome peptidase activities in vitro. Here we report new evidence that supports a hypothesis that intracellular ATP at the physiological levels bidirectionally regulates 26S proteasome proteolytic function in the cell. First, we confirmed that ATP exerted bidirectional regulation on the 26S proteasome in vitro, with the optimal ATP concentration (between 50–100 ?M) stimulating proteasome chymotrypsin-like activities. Second, we found that manipulating intracellular ATP levels also led to bidirectional changes in the levels of proteasome-specific protein substrates in cultured cells. Finally, measures to increase intracellular ATP enhanced, while decreasing intracellular ATP attenuated, the ability of proteasome inhibition to induce cell death. These data strongly suggest that endogenous ATP within the physiological concentration range can exert a negative impact on proteasome activities, allowing the cell to rapidly up-regulate proteasome activity upon ATP reduction under stress conditions. PMID:20805844

Huang, Hongbiao; Zhang, Xiaoyan; Li, Shujue; Liu, Ningning; Lian, Wen; McDowell, Emily; Zhou, Ping; Zhao, Canguo; Guo, Haiping; Zhang, Change; Yang, Changshan; Wen, Guangmei; Dong, Xiaoxian; Lu, Li; Ma, Ningfang; Dong, Weihua; Dou, Q. Ping; Wang, Xuejun; Liu, Jinbao

2010-01-01

71

43 CFR 10000.3 - Definitions.  

Code of Federal Regulations, 2011 CFR

...Interior Regulations Relating to Public Lands (Continued) UTAH RECLAMATION MITIGATION AND CONSERVATION COMMISSION ORGANIZATION...FUNCTIONS § 10000.3 Definitions. Act refers to the Central Utah Project Completion Act, Titles II, III, IV, V, and VI of...

2011-10-01

72

43 CFR 10000.3 - Definitions.  

Code of Federal Regulations, 2013 CFR

...Interior Regulations Relating to Public Lands (Continued) UTAH RECLAMATION MITIGATION AND CONSERVATION COMMISSION ORGANIZATION...FUNCTIONS § 10000.3 Definitions. Act refers to the Central Utah Project Completion Act, Titles II, III, IV, V, and VI of...

2013-10-01

73

43 CFR 10000.3 - Definitions.  

Code of Federal Regulations, 2012 CFR

...Interior Regulations Relating to Public Lands (Continued) UTAH RECLAMATION MITIGATION AND CONSERVATION COMMISSION ORGANIZATION...FUNCTIONS § 10000.3 Definitions. Act refers to the Central Utah Project Completion Act, Titles II, III, IV, V, and VI of...

2012-10-01

74

43 CFR 10000.3 - Definitions.  

Code of Federal Regulations, 2014 CFR

...Interior Regulations Relating to Public Lands (Continued) UTAH RECLAMATION MITIGATION AND CONSERVATION COMMISSION ORGANIZATION...FUNCTIONS § 10000.3 Definitions. Act refers to the Central Utah Project Completion Act, Titles II, III, IV, V, and VI of...

2014-10-01

75

50 CFR 230.2 - Definitions.  

Code of Federal Regulations, 2014 CFR

...person described in paragraph (1) of this definition. Calf means any whale less than 1 year old or having milk in its stomach. Commission means the International Whaling Commission established by article III of the Convention. Convention...

2014-10-01

76

50 CFR 230.2 - Definitions.  

Code of Federal Regulations, 2013 CFR

...person described in paragraph (1) of this definition. Calf means any whale less than 1 year old or having milk in its stomach. Commission means the International Whaling Commission established by article III of the Convention. Convention...

2013-10-01

77

50 CFR 230.2 - Definitions.  

Code of Federal Regulations, 2011 CFR

...person described in paragraph (1) of this definition. Calf means any whale less than 1 year old or having milk in its stomach. Commission means the International Whaling Commission established by article III of the Convention. Convention...

2011-10-01

78

48 CFR 245.601 - Definitions.  

Code of Federal Regulations, 2010 CFR

...Definitions. (1) Controlled substances means— (i) Narcotic, depressant, stimulant, or hallucinogenic drug or substance...substance controlled under Title II of the Comprehensive Drug Abuse Prevention and Control Act of 1970; or (iii) A...

2010-10-01

79

Differential expression of ATP7A, ATP7B and CTR1 in adult rat dorsal root ganglion tissue  

Microsoft Academic Search

BACKGROUND: ATP7A, ATP7B and CTR1 are metal transporting proteins that control the cellular disposition of copper and platinum drugs, but their expression in dorsal root ganglion (DRG) tissue and their role in platinum-induced neurotoxicity are unknown. To investigate the DRG expression of ATP7A, ATP7B and CTR1, lumbar DRG and reference tissues were collected for real time quantitative PCR, RT-PCR, immunohistochemistry

Virginia Ip; Johnson J Liu; Julian FB Mercer; Mark J McKeage

2010-01-01

80

Tripartite purinergic modulation of central respiratory networks during perinatal development: the influence of ATP, ectonucleotidases, and ATP metabolites.  

PubMed

ATP released during hypoxia from the ventrolateral medulla activates purinergic receptors (P2Rs) to attenuate the secondary hypoxic depression of breathing by a mechanism that likely involves a P2Y(1)R-mediated excitation of preBötzinger complex (preBötC) inspiratory rhythm-generating networks. In this study, we used rhythmically active in vitro preparations from embryonic and postnatal rats and ATP microinjection into the rostral ventral respiratory group (rVRG)/preBötC to reveal that these networks are sensitive to ATP when rhythm emerges at embryonic day 17 (E17). The peak frequency elicited by ATP at E19 and postnatally was the same ( approximately 45 bursts/min), but relative sensitivity was threefold greater at E19, reflecting a lower baseline frequency (5.6 +/- 0.9 vs 19.0 +/- 1.3 bursts/min). Combining microinjection techniques with ATP biosensors revealed that ATP concentration in the rVRG/preBötC falls rapidly as a result of active processes and closely correlates with inspiratory frequency. A phosphate assay established that preBötC-containing tissue punches degrade ATP at rates that increase perinatally. Thus, the agonist profile [ATP/ADP/adenosine (ADO)] produced after ATP release in the rVRG/preBötC will change perinatally. Electrophysiology further established that the ATP metabolite ADP is excitatory and that, in fetal but not postnatal animals, ADO at A(1) receptors exerts a tonic depressive action on rhythm, whereas A(1) antagonists extend the excitatory action of ATP on inspiratory rhythm. These data demonstrate that ATP is a potent excitatory modulator of the rVRG/preBötC inspiratory network from the time it becomes active and that ATP actions are determined by a dynamic interaction between the actions of ATP at P2 receptors, ectonucleotidases that degrade ATP, and ATP metabolites on P2Y and P1 receptors. PMID:19940166

Huxtable, Adrianne G; Zwicker, Jennifer D; Poon, Betty Y; Pagliardini, Silvia; Vrouwe, Sebastian Q; Greer, John J; Funk, Gregory D

2009-11-25

81

Potentiation of cytokine induction of group IIA phospholipase A2 in rat mesangial cells by ATP and adenosine via the A2A adenosine receptor  

PubMed Central

In rat mesangial cells extracellular nucleotides were found to increase arachidonic acid release by a cytosolic phospholipase A2 through the P2Y2 purinergic receptor. In this study we investigated the effects of ATP and UTP on interleukin-1? (IL-1?)-induced mRNA expression and activity of group IIA phospholipase A2 (sPLA2-IIA) in rat mesangial cells. Treatment of cells for 24?h with extracellular ATP potentiated IL-1?-stimulated sPLA2-IIA induction, whereas UTP had no effect. We obtained the following evidence that the P2Y2 receptor is not involved in the potentiation of sPLA2-IIA induction: (i) ATP-?-S had no enhancing effect; (ii) suramin, a P2 receptor antagonist, did not inhibit ATP-mediated potentiation; (iii) inhibition of degradation of extracellular nucleotides by the 5?-ectonucleotidase inhibitor AOPCP did not enhance sPLA2-IIA induction and (iv) adenosine deaminase treatment completely abolished the ATP-mediated potentiation of sPLA2-IIA induction. In contrast, treatment of mesangial cells with adenosine or the A2A receptor agonist CGS 21680 mimicked the effects of ATP in enhancing IL-1?-stimulated sPLA2-IIA induction, whereas the specific A2A receptor antagonist ZM 241385 completely abolished the potentiating effect of ATP or adenosine. The protein kinase A inhibitor Rp-8-Br-cyclic AMPS dose-dependently inhibited the enhancing effect of ATP or adenosine indicating the participation of an adenosine receptor-mediated cyclic AMP-dependent signalling pathway. These data indicate that ATP mediates proinflammatory long-term effects in rat mesangial cells via its degradation product adenosine through the A2A receptor resulting in potentiation of sPLA2-IIA induction. PMID:11156559

Scholz-Pedretti, Kirsten; Pfeilschifter, Josef; Kaszkin, Marietta

2001-01-01

82

Adenosine triphosphate (ATP) as a possible indicator of extraterrestrial biology  

NASA Technical Reports Server (NTRS)

The ubiquity of adenosine triphosphate (ATP) in terrestrial organisms provides the basis for proposing the assay of this vital metabolic intermediate for detecting extraterrestrial biological activity. If an organic carbon chemistry is present on the planets, the occurrence of ATP is possible either from biosynthetic or purely chemical reactions. However, ATP's relative complexity minimizes the probability of abiogenic synthesis. A sensitive technique for the quantitative detection of ATP was developed using the firefly bioluminescent reaction. The procedure was used successfully for the determination of the ATP content of soil and bacteria. This technique is also being investigated from the standpoint of its application in clinical medicine.

Chappelle, E. W.; Picciolo, G. L.

1974-01-01

83

ATP complex of Al 3+ as studied by PFG NMR  

NASA Astrophysics Data System (ADS)

Self diffusion coefficients of adenosine triphosphate (ATP) and its complex with Al 3+ are measured by pulsed field gradient (PFG) NMR technique. It is shown that the free ATP does not diffuse faster than the bound ATP, implying that the molecular size of the complex is not much larger than the free ATP. Based on the diffusion data and the 1H and 31P chemical shifts, it is suggested that the aluminium ion is chelated simultaneously by the adenosine nitrogen N-7 and the phosphate oxygen atoms in the same ATP molecule.

Huang, He; Liu, Maili; Mao, Xi-An

1998-07-01

84

Space shuttle (ATP configuration) abort staging investigation  

NASA Technical Reports Server (NTRS)

A wind tunnel test conducted in a 14-inch trisonic wind tunnel to determine the force and moment characteristics of the ATP Orbiter and modified ATP External Tank/SRB combination during abort staging conditions is discussed. Six component aerodynamic force and moment data were recorded for the orbiter and ET/SRB combination. Pitch polars were obtained for an angle of attack range from minus 10 to plus 10 degrees and orbiter incidence angles (orbiter relative to the ET/SRB combination) of 0 and 2 degrees. A limited amount of yaw data were obtained at 0 degree angle of attack and beta range from minus 10 to plus 10 degrees. In addition, orbiter pitch control effectiveness was determined at several grid points. These force and moment data were obtained for Mach numbers of 0.9, 1.2 and 2.0.

Rampy, J. M.; Blackwell, K. L.; Allen, E. C., Jr.; Fossler, I.

1973-01-01

85

ATP synthase: a tentative structural model.  

PubMed

Adenosine triphosphate (ATP) synthase produces ATP from ADP and inorganic phosphate at the expense of proton- or sodium-motive force across the respective coupling membrane in Archaea, Bacteria and Eucarya. Cation flow through the intrinsic membrane portion of this enzyme (Fo, subunits ab2c9-12) and substrate turnover in the headpiece (F1, subunits alpha3beta3 gammadeltaepsilon) are mechanically coupled by the rotation of subunit gamma in the center of the catalytic hexagon of subunits (alphabeta)3 in F1. ATP synthase is the smallest rotatory engine in nature. With respect to the headpiece alone, it probably operates with three steps. Partial structures of six out of its at least eight different subunits have been published and a 3-dimensional structure is available for the assembly (alphabeta)3gamma. In this article, we review the available structural data and build a tentative topological model of the holoenzyme. The rotor portion is proposed to consist of a wheel of at least nine copies of subunits c, epsilon and a portion of gamma as a spoke, and another portion of gamma as a crankshaft. The stator is made up from a, the transmembrane portion of b2, delta and the catalytic hexagon of (alphabeta)3. As an educated guess, the model may be of heuristic value for ongoing studies on this fascinating electrochemical-to-mechanical-to-chemical transducer. PMID:9323021

Engelbrecht, S; Junge, W

1997-09-15

86

Loss of LRPPRC causes ATP synthase deficiency  

PubMed Central

Defects of the oxidative phosphorylation system, in particular of cytochrome-c oxidase (COX, respiratory chain complex IV), are common causes of Leigh syndrome (LS), which is a rare neurodegenerative disorder with severe progressive neurological symptoms that usually present during infancy or early childhood. The COX-deficient form of LS is commonly caused by mutations in genes encoding COX assembly factors, e.g. SURF1, SCO1, SCO2 or COX10. However, other mutations affecting genes that encode proteins not directly involved in COX assembly can also cause LS. The leucine-rich pentatricopeptide repeat containing protein (LRPPRC) regulates mRNA stability, polyadenylation and coordinates mitochondrial translation. In humans, mutations in Lrpprc cause the French Canadian type of LS. Despite the finding that LRPPRC deficiency affects the stability of most mitochondrial mRNAs, its pathophysiological effect has mainly been attributed to COX deficiency. Surprisingly, we show here that the impaired mitochondrial respiration and reduced ATP production observed in Lrpprc conditional knockout mouse hearts is caused by an ATP synthase deficiency. Furthermore, the appearance of inactive subassembled ATP synthase complexes causes hyperpolarization and increases mitochondrial reactive oxygen species production. Our findings shed important new light on the bioenergetic consequences of the loss of LRPPRC in cardiac mitochondria. PMID:24399447

Mourier, Arnaud; Ruzzenente, Benedetta; Brandt, Tobias; Kühlbrandt, Werner; Larsson, Nils-Göran

2014-01-01

87

ATP synthases from archaea: the beauty of a molecular motor.  

PubMed

Archaea live under different environmental conditions, such as high salinity, extreme pHs and cold or hot temperatures. How energy is conserved under such harsh environmental conditions is a major question in cellular bioenergetics of archaea. The key enzymes in energy conservation are the archaeal A1AO ATP synthases, a class of ATP synthases distinct from the F1FO ATP synthase ATP synthase found in bacteria, mitochondria and chloroplasts and the V1VO ATPases of eukaryotes. A1AO ATP synthases have distinct structural features such as a collar-like structure, an extended central stalk, and two peripheral stalks possibly stabilizing the A1AO ATP synthase during rotation in ATP synthesis/hydrolysis at high temperatures as well as to provide the storage of transient elastic energy during ion-pumping and ATP synthesis/-hydrolysis. High resolution structures of individual subunits and subcomplexes have been obtained in recent years that shed new light on the function and mechanism of this unique class of ATP synthases. An outstanding feature of archaeal A1AO ATP synthases is their diversity in size of rotor subunits and the coupling ion used for ATP synthesis with H(+), Na(+) or even H(+) and Na(+) using enzymes. The evolution of the H(+) binding site to a Na(+) binding site and its implications for the energy metabolism and physiology of the cell are discussed. PMID:24650628

Grüber, Gerhard; Manimekalai, Malathy Sony Subramanian; Mayer, Florian; Müller, Volker

2014-06-01

88

Measurement of chloroplast ATP synthesis activity in Arabidopsis.  

PubMed

There are numerous options for monitoring ATP synthesis in chloroplasts using isolated thylakoid membranes, intact chloroplasts, and even whole leaves. Currently, the most commonly used method employs isolated thylakoids coupling the synthesis of ATP to light emission from luciferin in a reaction catalyzed by luciferase. The luciferin-luciferase assay can be highly sensitive and is a direct measure of ATP. Another direct measurement of ATP is the incorporation of 32P into ATP, which, while more technically difficult, has the advantage over the luciferin-luciferase assay of being able to distinguish newly synthesized from total ATP. The phosphorylation of ADP results in a net decrease in pKa (acid disassociation constant) between the reactants and the product ATP, resulting in an increase in the pH of the assay media, which can be used as a convenient, continuous measurement of ATP synthesis. The formation of ??H+ across the thylakoid membrane and its concomitant dissipation as ATP is synthesized can be measured by an electrochromic absorption band shift (ECS) of thylakoid pigments measured at 518 nm (Witt, Biochim. Biophys. Acta 505:355-427, 1979; Petty and Jackson, Biochim. Biophys. Acta: Bioenergetics 547:463-473, 1979). The first-order decay time of the ESC can be used to estimate the rate of ATP synthesis providing a noninvasive, indirect method for measuring ATP synthase activity that can be used with intact leaves. PMID:21863453

Grennan, Aleel K; Ort, Donald R

2011-01-01

89

A New Type of Na+-Driven ATP Synthase Membrane Rotor with a Two-Carboxylate Ion-Coupling Motif  

PubMed Central

The anaerobic bacterium Fusobacterium nucleatum uses glutamate decarboxylation to generate a transmembrane gradient of Na+. Here, we demonstrate that this ion-motive force is directly coupled to ATP synthesis, via an F1Fo-ATP synthase with a novel Na+ recognition motif, shared by other human pathogens. Molecular modeling and free-energy simulations of the rotary element of the enzyme, the c-ring, indicate Na+ specificity in physiological settings. Consistently, activity measurements showed Na+ stimulation of the enzyme, either membrane-embedded or isolated, and ATP synthesis was sensitive to the Na+ ionophore monensin. Furthermore, Na+ has a protective effect against inhibitors targeting the ion-binding sites, both in the complete ATP synthase and the isolated c-ring. Definitive evidence of Na+ coupling is provided by two identical crystal structures of the c11 ring, solved by X-ray crystallography at 2.2 and 2.6 Å resolution, at pH 5.3 and 8.7, respectively. Na+ ions occupy all binding sites, each coordinated by four amino acids and a water molecule. Intriguingly, two carboxylates instead of one mediate ion binding. Simulations and experiments demonstrate that this motif implies that a proton is concurrently bound to all sites, although Na+ alone drives the rotary mechanism. The structure thus reveals a new mode of ion coupling in ATP synthases and provides a basis for drug-design efforts against this opportunistic pathogen. PMID:23824040

Schulz, Sarah; Iglesias-Cans, Marina; Krah, Alexander; Yildiz, Özkan; Leone, Vanessa; Matthies, Doreen; Cook, Gregory M.

2013-01-01

90

Early opening of sarcolemmal ATP-sensitive potassium channels is not a key step in PKC-mediated cardioprotection.  

PubMed

ATP-sensitive potassium (KATP) channels are abundantly expressed in the myocardium. Although a definitive role for the channel remains elusive they have been implicated in the phenomenon of cardioprotection, but the precise mechanism is unclear. We set out to test the hypothesis that the channel protects by opening early during ischemia to shorten action potential duration and reduce electrical excitability thus sparing intracellular ATP. This could reduce reperfusion injury by improving calcium homeostasis. Using a combination of contractile function analysis, calcium fluorescence imaging and patch clamp electrophysiology in cardiomyocytes isolated from adult male Wistar rats, we demonstrated that the opening of sarcolemmal KATP channels was markedly delayed after cardioprotective treatments: ischemic preconditioning, adenosine and PMA. This was due to the preservation of intracellular ATP for longer during simulated ischemia therefore maintaining sarcolemmal KATP channels in the closed state for longer. As the simulated ischemia progressed, KATP channels opened to cause contractile, calcium transient and action potential failure; however there was no indication of any channel activity early during simulated ischemia to impart an energy sparing hyperpolarization or action potential shortening. We present compelling evidence to demonstrate that an early opening of sarcolemmal KATP channels during simulated ischemia is not part of the protective mechanism imparted by ischemic preconditioning or other PKC-dependent cardioprotective stimuli. On the contrary, channel opening was actually delayed. We conclude that sarcolemmal KATP channel opening is a consequence of ATP depletion, not a primary mechanism of ATP preservation in these cells. PMID:25450614

Brennan, Sean; Jackson, Robert; Patel, Manish; Sims, Mark W; Hudman, Diane; Norman, Robert I; Lodwick, David; Rainbow, Richard D

2015-02-01

91

Mycobacterium tuberculosis Universal Stress Protein Rv2623 Regulates Bacillary Growth by ATP Binding: Requirement for Establishing Chronic Persistent Infection  

SciTech Connect

Tuberculous latency and reactivation play a significant role in the pathogenesis of tuberculosis, yet the mechanisms that regulate these processes remain unclear. The Mycobacterium tuberculosisuniversal stress protein (USP) homolog, rv2623, is among the most highly induced genes when the tubercle bacillus is subjected to hypoxia and nitrosative stress, conditions thought to promote latency. Induction of rv2623 also occurs when M. tuberculosis encounters conditions associated with growth arrest, such as the intracellular milieu of macrophages and in the lungs of mice with chronic tuberculosis. Therefore, we tested the hypothesis that Rv2623 regulates tuberculosis latency. We observed that an Rv2623-deficient mutant fails to establish chronic tuberculous infection in guinea pigs and mice, exhibiting a hypervirulence phenotype associated with increased bacterial burden and mortality. Consistent with this in vivo growth-regulatory role, constitutive overexpression of rv2623 attenuates mycobacterial growth in vitro. Biochemical analysis of purified Rv2623 suggested that this mycobacterial USP binds ATP, and the 2.9-A-resolution crystal structure revealed that Rv2623 engages ATP in a novel nucleotide-binding pocket. Structure-guided mutagenesis yielded Rv2623 mutants with reduced ATP-binding capacity. Analysis of mycobacteria overexpressing these mutants revealed that the in vitro growth-inhibitory property of Rv2623 correlates with its ability to bind ATP. Together, the results indicate that i M. tuberculosis Rv2623 regulates mycobacterial growth in vitro and in vivo, and ii Rv2623 is required for the entry of the tubercle bacillus into the chronic phase of infection in the host; in addition, iii Rv2623 binds ATP; and iv the growth-regulatory attribute of this USP is dependent on its ATP-binding activity. We propose that Rv2623 may function as an ATP-dependent signaling intermediate in a pathway that promotes persistent infection.

Drumm, J.; Mi, K; Bilder, P; Sun, M; Lim, J; Bielefeldt-Ohmann, H; Basaraba, R; So, M; Zhu, G; et. al.

2009-01-01

92

Effect of ATP binding cassette/multidrug resistance proteins on ATP efflux of Saccharomyces cerevisiae.  

PubMed

Multidrug resistance (MDR) in mammalian tumors or tissues is often associated with the overexpression of the putative drug efflux pump P-glycoprotein (Pgp). One theory concerning the mechanism of Pgp activity is that efflux of ATP is coupled to drug efflux. Evidence in support of this theory has been observed in mammalian cells. Recently, the STS1 gene, which is a multidrug resistance gene related to the mammalian Pgp's, has been characterized in S. cerevisiae. Also, the mouse mdr3 Pgp has been functionally expressed in yeast cells. Therefore, it was of interest to determine whether the expression of these proteins affected ATP efflux from yeast. Although both genes were shown to confer MDR, thus confirming functional expression, the endogenous glucose-dependent, drug-stimulated ATP efflux activity of yeast was not affected by expression of STS1, and was decreased by the expression of mouse mdr3. PMID:9020050

Boyum, R; Guidotti, G

1997-01-01

93

Bioanalytical Applications of Real-Time ATP Imaging Via Bioluminescence  

SciTech Connect

The research discussed within involves the development of novel applications of real-time imaging of adenosine 5'-triphosphate (ATP). ATP was detected via bioluminescence and the firefly luciferase-catalyzed reaction of ATP and luciferin. The use of a microscope and an imaging detector allowed for spatially resolved quantitation of ATP release. Employing this method, applications in both biological and chemical systems were developed. First, the mechanism by which the compound 48/80 induces release of ATP from human umbilical vein endothelial cells (HUVECs) was investigated. Numerous enzyme activators and inhibitors were utilized to probe the second messenger systems involved in release. Compound 48/80 activated a G{sub q}-type protein to initiate ATP release from HUVECs. Ca{sup 2+} imaging along with ATP imaging revealed that activation of phospholipase C and induction of intracellular Ca{sup 2+} signaling were necessary for release of ATP. Furthermore, activation of protein kinase C inhibited the activity of phospholipase C and thus decreased the magnitude of ATP release. This novel release mechanism was compared to the existing theories of extracellular release of ATP. Bioluminescence imaging was also employed to examine the role of ATP in the field of neuroscience. The central nervous system (CNS) was dissected from the freshwater snail Lymnaea stagnalis. Electrophysiological experiments demonstrated that the neurons of the Lymnaea were not damaged by any of the components of the imaging solution. ATP was continuously released by the ganglia of the CNS for over eight hours and varied from ganglion to ganglion and within individual ganglia. Addition of the neurotransmitters K{sup +} and serotonin increased release of ATP in certain regions of the Lymnaea CNS. Finally, the ATP imaging technique was investigated for the study of drug release systems. MCM-41-type mesoporous nanospheres were loaded with ATP and end-capped with mercaptoethanol functionalized CdS monocrystals. Aggregates of nanospheres were bathed in imaging solution, and ATP bioluminescence was monitored to investigated the release kinetics of the nanosphere drug delivery systems. Addition of disulfide bond-cleaving molecules induced uncapping of the nanospheres and subsequently, the release of ATP. Increasing the concentration of the uncapping molecule decreased the temporal maximum and increased the magnitude of release of encapsulated ATP from the nanospheres. Furthermore, the release kinetics from the nanospheres varied with the size of the particle aggregates.

Jason Alan Gruenhagen

2003-12-12

94

Mtabolisme actyl CoA, acide citrique,ADP, arobie, anabolisme, anarobie,ATP,ATP-  

E-print Network

, catabolisme, chaîne de transport des électrons, coenzyme, cycle de Krebs, cytochrome, cytosol, dette d dinucléotide (une coenzyme) 7 Glycolyse: bilan · �nergie nette 2 ATP · Les deux molécules de pyruvate servent oxaloacétate acétyl CoA H2O H2O CO2 + CO2 + Coenzyme A + Coenzyme A AdP FADH2 NADH NADH H2O NADH ATP 12 #12

Blouin-Demers, Gabriel

95

Kinetic mechanism of the dimeric ATP sulfurylase from plants.  

PubMed

In plants, sulfur must be obtained from the environment and assimilated into usable forms for metabolism. ATP sulfurylase catalyses the thermodynamically unfavourable formation of a mixed phosphosulfate anhydride in APS (adenosine 5'-phosphosulfate) from ATP and sulfate as the first committed step of sulfur assimilation in plants. In contrast to the multi-functional, allosterically regulated ATP sulfurylases from bacteria, fungi and mammals, the plant enzyme functions as a mono-functional, non-allosteric homodimer. Owing to these differences, here we examine the kinetic mechanism of soybean ATP sulfurylase [GmATPS1 (Glycine max (soybean) ATP sulfurylase isoform 1)]. For the forward reaction (APS synthesis), initial velocity methods indicate a single-displacement mechanism. Dead-end inhibition studies with chlorate showed competitive inhibition versus sulfate and non-competitive inhibition versus APS. Initial velocity studies of the reverse reaction (ATP synthesis) demonstrate a sequential mechanism with global fitting analysis suggesting an ordered binding of substrates. ITC (isothermal titration calorimetry) showed tight binding of APS to GmATPS1. In contrast, binding of PPi (pyrophosphate) to GmATPS1 was not detected, although titration of the E•APS complex with PPi in the absence of magnesium displayed ternary complex formation. These results suggest a kinetic mechanism in which ATP and APS are the first substrates bound in the forward and reverse reactions, respectively. PMID:23789618

Ravilious, Geoffrey E; Herrmann, Jonathan; Goo Lee, Soon; Westfall, Corey S; Jez, Joseph M

2013-01-01

96

ATP-sulfurylase, sulfur-compounds, and plant stress tolerance  

PubMed Central

Sulfur (S) stands fourth in the list of major plant nutrients after N, P, and K. Sulfate (SO42-), a form of soil-S taken up by plant roots is metabolically inert. As the first committed step of S-assimilation, ATP-sulfurylase (ATP-S) catalyzes SO42--activation and yields activated high-energy compound adenosine-5?-phosphosulfate that is reduced to sulfide (S2-) and incorporated into cysteine (Cys). In turn, Cys acts as a precursor or donor of reduced S for a range of S-compounds such as methionine (Met), glutathione (GSH), homo-GSH (h-GSH), and phytochelatins (PCs). Among S-compounds, GSH, h-GSH, and PCs are known for their involvement in plant tolerance to varied abiotic stresses, Cys is a major component of GSH, h-GSH, and PCs; whereas, several key stress-metabolites such as ethylene, are controlled by Met through its first metabolite S-adenosylmethionine. With the major aim of briefly highlighting S-compound-mediated role of ATP-S in plant stress tolerance, this paper: (a) overviews ATP-S structure/chemistry and occurrence, (b) appraises recent literature available on ATP-S roles and regulations, and underlying mechanisms in plant abiotic and biotic stress tolerance, (c) summarizes ATP-S-intrinsic regulation by major S-compounds, and (d) highlights major open-questions in the present context. Future research in the current direction can be devised based on the discussion outcomes. PMID:25904923

Anjum, Naser A.; Gill, Ritu; Kaushik, Manjeri; Hasanuzzaman, Mirza; Pereira, Eduarda; Ahmad, Iqbal; Tuteja, Narendra; Gill, Sarvajeet S.

2015-01-01

97

Kinetic mechanism of the dimeric ATP sulfurylase from plants  

PubMed Central

In plants, sulfur must be obtained from the environment and assimilated into usable forms for metabolism. ATP sulfurylase catalyses the thermodynamically unfavourable formation of a mixed phosphosulfate anhydride in APS (adenosine 5?-phosphosulfate) from ATP and sulfate as the first committed step of sulfur assimilation in plants. In contrast to the multi-functional, allosterically regulated ATP sulfurylases from bacteria, fungi and mammals, the plant enzyme functions as a mono-functional, non-allosteric homodimer. Owing to these differences, here we examine the kinetic mechanism of soybean ATP sulfurylase [GmATPS1 (Glycine max (soybean) ATP sulfurylase isoform 1)]. For the forward reaction (APS synthesis), initial velocity methods indicate a single-displacement mechanism. Dead-end inhibition studies with chlorate showed competitive inhibition versus sulfate and non-competitive inhibition versus APS. Initial velocity studies of the reverse reaction (ATP synthesis) demonstrate a sequential mechanism with global fitting analysis suggesting an ordered binding of substrates. ITC (isothermal titration calorimetry) showed tight binding of APS to GmATPS1. In contrast, binding of PPi (pyrophosphate) to GmATPS1 was not detected, although titration of the E•APS complex with PPi in the absence of magnesium displayed ternary complex formation. These results suggest a kinetic mechanism in which ATP and APS are the first substrates bound in the forward and reverse reactions, respectively. PMID:23789618

Ravilious, Geoffrey E.; Herrmann, Jonathan; Goo Lee, Soon; Westfall, Corey S.; Jez, Joseph M.

2013-01-01

98

Thioredoxin-insensitive plastid ATP synthase that performs moonlighting functions  

PubMed Central

The chloroplast ATP synthase catalyzes the light-driven synthesis of ATP and acts as a key feedback regulatory component of photosynthesis. Arabidopsis possesses two homologues of the regulatory ? subunit of the ATP synthase, encoded by the ATPC1 and ATPC2 genes. Using a series of mutants, we show that both these subunits can support photosynthetic ATP synthesis in vivo with similar specific activities, but that in wild-type plants, only ?1 is involved in ATP synthesis in photosynthesis. The ?1-containing ATP synthase shows classical light-induced redox regulation, whereas the mutant expressing only ?2-ATP synthase (gamma exchange-revised ATP synthase, gamera) shows equally high ATP synthase activity in the light and dark. In situ redox titrations demonstrate that the regulatory thiol groups on ?2-ATP synthase remain reduced under physiological conditions but can be oxidized by the strong oxidant diamide, implying that the redox potential for the thiol/disulphide transition in ?2 is substantially higher than that for ?1. This regulatory difference may be attributed to alterations in the residues near the redox-active thiols. We propose that ?2-ATP synthase functions to catalyze ATP hydrolysis-driven proton translocation in nonphotosynthetic plastids, maintaining a sufficient transthylakoid proton gradient to drive protein translocation or other processes. Consistent with this interpretation, ATPC2 is predominantly expressed in the root, whereas modifying its expression results in alteration of root hair development. Phylogenetic analysis suggests that ?2 originated from ancient gene duplication, resulting in divergent evolution of functionally distinct ATP synthase complexes in dicots and mosses. PMID:22328157

Kohzuma, Kaori; Dal Bosco, Cristina; Kanazawa, Atsuko; Dhingra, Amit; Nitschke, Wolfgang; Meurer, Jörg; Kramer, David M.

2012-01-01

99

Evaluation of ATP content in hair bulbs in human scalp.  

PubMed

The content of ATP in scalp hair bulbs in humans was measured in the hair roots from 15 healthy volunteers. Light and electron microscopy confirmed the presence of outer and an inner root sheaths in the root of pulled out anagen hair. Incubation of samples in buffer solution led to extraction of ATP, which was measured by the chemiluminescent method. Mechanic disintegration of hair bulbs and their freezing-defrosting did not increase ATP output. The results of microscopy indicated that ATP extraction procedure was associated with separation of the outer radical sheath from the inner one without impairing the structure of the inner sheath. The mean content of ATP was 12 ± 2 pmol per bulb. The use of pulled out hair bulbs for ATP measurements simplified the procedure as involved no surgical removal of follicles. PMID:24909726

Mikhal'chik, E V; Suprun, M V; Fedorkova, M V; Ibragimova, G A; Dmitrieva, E I; Lipatova, V A; Kutsev, S I

2014-05-01

100

Single molecule thermodynamics of ATP synthesis by F1-ATPase  

NASA Astrophysics Data System (ADS)

FoF1-ATP synthase is a factory for synthesizing ATP in virtually all cells. Its core machinery is the subcomplex F1-motor (F1-ATPase) and performs the reversible mechanochemical coupling. The isolated F1-motor hydrolyzes ATP, which is accompanied by unidirectional rotation of its central ? -shaft. When a strong opposing torque is imposed, the ? -shaft rotates in the opposite direction and drives the F1-motor to synthesize ATP. This mechanical-to-chemical free-energy transduction is the final and central step of the multistep cellular ATP-synthetic pathway. Here, we determined the amount of mechanical work exploited by the F1-motor to synthesize an ATP molecule during forced rotations using a methodology combining a nonequilibrium theory and single molecule measurements of responses to external torque. We found that the internal dissipation of the motor is negligible even during rotations far from a quasistatic process.

Toyabe, Shoichi; Muneyuki, Eiro

2015-01-01

101

Single molecule thermodynamics of ATP synthesis by F$_1$-ATPase  

E-print Network

F$_\\mathrm{o}$F$_1$-ATP synthase is a factory for synthesizing ATP in virtually all cells. Its core machinery is the subcomplex F$_1$-motor (F$_1$-ATPase) and performs the reversible mechanochemical coupling. Isolated F$_1$-motor hydrolyzes ATP, which is accompanied by unidirectional rotation of its central $\\gamma$-shaft. When a strong opposing torque is imposed, the $\\gamma$-shaft rotates in the opposite direction and drives the F$_1$-motor to synthesize ATP. This mechanical-to-chemical free-energy transduction is the final and central step of the multistep cellular ATP-synthetic pathway. Here, we determined the amount of mechanical work exploited by the F$_1$-motor to synthesize an ATP molecule during forced rotations using methodology combining a nonequilibrium theory and single molecule measurements of responses to external torque. We found that the internal dissipation of the motor is negligible even during rotations far from a quasistatic process.

Shoichi Toyabe; Eiro Muneyuki

2015-01-16

102

ATP7B detoxifies silver in ciliated airway epithelial cells  

SciTech Connect

Silver is a centuries-old antibiotic agent currently used to treat infected burns. The sensitivity of a wide range of drug-resistant microorganisms to silver killing suggests that it may be useful for treating refractory lung infections. Toward this goal, we previously developed a methylated caffeine silver acetate compound, SCC1, that exhibits broad-spectrum antimicrobial activity against clinical strains of bacteria in vitro and when nebulized to lungs in mouse infection models. Preclinical testing of high concentrations of SCC1 in primary culture mouse tracheal epithelial cells (mTEC) showed selective ciliated cell death. Ciliated cell death was induced by both silver- and copper-containing compounds but not by the methylated caffeine portion of SCC1. We hypothesized that copper transporting P-type ATPases, ATP7A and ATP7B, play a role in silver detoxification in the airway. In mTEC, ATP7A was expressed in non-ciliated cells, whereas ATP7B was expressed only in ciliated cells. The exposure of mTEC to SCC1 induced the trafficking of ATP7B, but not ATP7A, suggesting the presence of a cell-specific silver uptake and detoxification mechanisms. Indeed, the expression of the copper uptake protein CTR1 was also restricted to ciliated cells. A role of ATP7B in silver detoxification was further substantiated when treatment of SCC1 significantly increased cell death in ATP7B shRNA-treated HepG2 cells. In addition, mTEC from ATP7B{sup -/-} mice showed enhanced loss of ciliated cells compared to wild type. These studies are the first to demonstrate a cell type-specific expression of the Ag{sup +}/Cu{sup +} transporters ATP7A, ATP7B, and CTR1 in airway epithelial cells and a role for ATP7B in detoxification of these metals in the lung.

Ibricevic, Aida, E-mail: aidaibricevic@hotmail.co [Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110 (United States); Brody, Steven L., E-mail: sbrody@dom.wustl.ed [Department of Medicine, Washington University School of Medicine, St. Louis, MO 63110 (United States); Youngs, Wiley J., E-mail: youngs@uakron.ed [Department of Chemistry, University of Akron, Akron, OH 44325 (United States); Cannon, Carolyn L., E-mail: carolyn.cannon@utsouthwestern.ed [Department of Pediatrics, Washington University School of Medicine, St. Louis, MO 63110 (United States)

2010-03-15

103

From ATP to Timed Graphs and Hybrid Systems  

Microsoft Academic Search

The paper presents results of ongoing work aiming at the unification of some behavioraldescription formalisms for timed systems.We propose for the algebra of timed processes ATP a very general semantics in terms ofa time domain.It is then shown how ATP can be translated into a variant of timed graphs. This resultallows the application of existing model-checking techniques to ATP.Finally, we

Xavier Nicollin; Joseph Sifakis; Sergio Yovine

1993-01-01

104

Two ATP-activated conductances in bullfrog atrial cells  

Microsoft Academic Search

A B S T R A C T Currents activated by extracellular ATP were studied in single voltage-clamped bullfrog atrial cells. Rapid application of ATP elicited currents carried through two different conductance pathways: a rapidly desensitizing conductance reversing near -10 mV, and a maintained, inwardly rectifying conductance reversing near -85 mV. ATP activated the desensitizing compo- nent of current with

DAVID D. FRIEL; BRUCE P. BEAN

1988-01-01

105

ATP5H/KCTD2 locus is associated with Alzheimer's disease risk  

PubMed Central

To identify loci associated with Alzheimer disease, we conducted a three-stage analysis using existing genome-wide association studies (GWAS) and genotyping in a new sample. In Stage I, all suggestive single-nucleotide polymorphisms (at P<0.001) in a previously reported GWAS of seven independent studies (8082 Alzheimer's disease (AD) cases; 12?040 controls) were selected, and in Stage II these were examined in an in silico analysis within the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium GWAS (1367 cases and 12904 controls). Six novel signals reaching P<5 × 10?6 were genotyped in an independent Stage III sample (the Fundació ACE data set) of 2200 sporadic AD patients and 2301 controls. We identified a novel association with AD in the adenosine triphosphate (ATP) synthase, H+ transporting, mitochondrial F0 (ATP5H)/Potassium channel tetramerization domain-containing protein 2 (KCTD2) locus, which reached genome-wide significance in the combined discovery and genotyping sample (rs11870474, odds ratio (OR)=1.58, P=2.6 × 10?7 in discovery and OR=1.43, P=0.004 in Fundació ACE data set; combined OR=1.53, P=4.7 × 10?9). This ATP5H/KCTD2 locus has an important function in mitochondrial energy production and neuronal hyperpolarization during cellular stress conditions, such as hypoxia or glucose deprivation. PMID:23857120

Boada, M; Antúnez, C; Ramírez-Lorca, R; DeStefano, A L; González-Pérez, A; Gayán, J; López-Arrieta, J; Ikram, M A; Hernández, I; Marín, J; Galán, J J; Bis, J C; Mauleón, A; Rosende-Roca, M; Moreno-Rey, C; Gudnasson, V; Morón, F J; Velasco, J; Carrasco, J M; Alegret, M; Espinosa, A; Vinyes, G; Lafuente, A; Vargas, L; Fitzpatrick, A L; Launer, L J; Sáez, M E; Vázquez, E; Becker, J T; López, O L; Serrano-Ríos, M; Tárraga, L; van Duijn, C M; Real, L M; Seshadri, S; Ruiz, A

2014-01-01

106

ATP5H/KCTD2 locus is associated with Alzheimer's disease risk.  

PubMed

To identify loci associated with Alzheimer disease, we conducted a three-stage analysis using existing genome-wide association studies (GWAS) and genotyping in a new sample. In Stage I, all suggestive single-nucleotide polymorphisms (at P<0.001) in a previously reported GWAS of seven independent studies (8082 Alzheimer's disease (AD) cases; 12?040 controls) were selected, and in Stage II these were examined in an in silico analysis within the Cohorts for Heart and Aging Research in Genomic Epidemiology consortium GWAS (1367 cases and 12904 controls). Six novel signals reaching P<5 × 10(-6) were genotyped in an independent Stage III sample (the Fundació ACE data set) of 2200 sporadic AD patients and 2301 controls. We identified a novel association with AD in the adenosine triphosphate (ATP) synthase, H+ transporting, mitochondrial F0 (ATP5H)/Potassium channel tetramerization domain-containing protein 2 (KCTD2) locus, which reached genome-wide significance in the combined discovery and genotyping sample (rs11870474, odds ratio (OR)=1.58, P=2.6 × 10(-7) in discovery and OR=1.43, P=0.004 in Fundació ACE data set; combined OR=1.53, P=4.7 × 10(-9)). This ATP5H/KCTD2 locus has an important function in mitochondrial energy production and neuronal hyperpolarization during cellular stress conditions, such as hypoxia or glucose deprivation. PMID:23857120

Boada, M; Antúnez, C; Ramírez-Lorca, R; DeStefano, A L; González-Pérez, A; Gayán, J; López-Arrieta, J; Ikram, M A; Hernández, I; Marín, J; Galán, J J; Bis, J C; Mauleón, A; Rosende-Roca, M; Moreno-Rey, C; Gudnasson, V; Morón, F J; Velasco, J; Carrasco, J M; Alegret, M; Espinosa, A; Vinyes, G; Lafuente, A; Vargas, L; Fitzpatrick, A L; Launer, L J; Sáez, M E; Vázquez, E; Becker, J T; López, O L; Serrano-Ríos, M; Tárraga, L; van Duijn, C M; Real, L M; Seshadri, S; Ruiz, A

2014-06-01

107

Diversity and regulation of ATP sulfurylase in photosynthetic organisms  

PubMed Central

ATP sulfurylase (ATPS) catalyzes the first committed step in the sulfate assimilation pathway, the activation of sulfate prior to its reduction. ATPS has been studied in only a few model organisms and even in these cases to a much smaller extent than the sulfate reduction and cysteine synthesis enzymes. This is possibly because the latter were considered of greater regulatory importance for sulfate assimilation. Recent evidences (reported in this paper) challenge this view and suggest that ATPS may have a crucial regulatory role in sulfate assimilation, at least in algae. In the ensuing text, we summarize the current knowledge on ATPS, with special attention to the processes that control its activity and gene(s) expression in algae. Special attention is given to algae ATPS proteins. The focus on algae is the consequence of the fact that a comprehensive investigation of ATPS revealed that the algal enzymes, especially those that are most likely involved in the pathway of sulfate reduction to cysteine, possess features that are not present in other organisms. Remarkably, algal ATPS proteins show a great diversity of isoforms and a high content of cysteine residues, whose positions are often conserved. According to the occurrence of cysteine residues, the ATPS of eukaryotic algae is closer to that of marine cyanobacteria of the genera Synechococcus and Prochlorococcus and is more distant from that of freshwater cyanobacteria. These characteristics might have evolved in parallel with the radiation of algae in the oceans and the increase of sulfate concentration in seawater. PMID:25414712

Prioretti, Laura; Gontero, Brigitte; Hell, Ruediger; Giordano, Mario

2014-01-01

108

Diversity and regulation of ATP sulfurylase in photosynthetic organisms.  

PubMed

ATP sulfurylase (ATPS) catalyzes the first committed step in the sulfate assimilation pathway, the activation of sulfate prior to its reduction. ATPS has been studied in only a few model organisms and even in these cases to a much smaller extent than the sulfate reduction and cysteine synthesis enzymes. This is possibly because the latter were considered of greater regulatory importance for sulfate assimilation. Recent evidences (reported in this paper) challenge this view and suggest that ATPS may have a crucial regulatory role in sulfate assimilation, at least in algae. In the ensuing text, we summarize the current knowledge on ATPS, with special attention to the processes that control its activity and gene(s) expression in algae. Special attention is given to algae ATPS proteins. The focus on algae is the consequence of the fact that a comprehensive investigation of ATPS revealed that the algal enzymes, especially those that are most likely involved in the pathway of sulfate reduction to cysteine, possess features that are not present in other organisms. Remarkably, algal ATPS proteins show a great diversity of isoforms and a high content of cysteine residues, whose positions are often conserved. According to the occurrence of cysteine residues, the ATPS of eukaryotic algae is closer to that of marine cyanobacteria of the genera Synechococcus and Prochlorococcus and is more distant from that of freshwater cyanobacteria. These characteristics might have evolved in parallel with the radiation of algae in the oceans and the increase of sulfate concentration in seawater. PMID:25414712

Prioretti, Laura; Gontero, Brigitte; Hell, Ruediger; Giordano, Mario

2014-01-01

109

Application of luciferase assay for ATP to antimicrobial drug susceptibility  

NASA Technical Reports Server (NTRS)

The susceptibility of bacteria, particularly those derived from body fluids, to antimicrobial agents is determined in terms of an ATP index measured by culturing a bacterium in a growth medium. The amount of ATP is assayed in a sample of the cultured bacterium by measuring the amount of luminescent light emitted when the bacterial ATP is reacted with a luciferase-luciferin mixture. The sample of the cultured bacterium is subjected to an antibiotic agent. The amount of bacterial adenosine triphosphate is assayed after treatment with the antibiotic by measuring the luminescent light resulting from the reaction. The ATP index is determined from the values obtained from the assay procedures.

Chappelle, E. W.; Picciolo, G. L.; Vellend, H.; Tuttle, S. A.; Barza, M. J.; Weinstein, L. (inventors)

1977-01-01

110

Quantal Release of ATP in Mouse Cortex  

PubMed Central

Transient currents occur at rest in cortical neurones that reflect the quantal release of transmitters such as glutamate and ?-aminobutyric acid (GABA). We found a bimodal amplitude distribution for spontaneously occurring inward currents recorded from mouse pyramidal neurones in situ, in acutely isolated brain slices superfused with picrotoxin. Larger events were blocked by glutamate receptor (AMPA, kainate) antagonists; smaller events were partially inhibited by P2X receptor antagonists suramin and PPADS. The decay of the larger events was selectively prolonged by cyclothiazide. Stimulation of single intracortical axons elicited quantal glutamate-mediated currents and also quantal currents with amplitudes corresponding to the smaller spontaneous inward currents. It is likely that the lower amplitude spontaneous events reflect packaged ATP release. This occurs with a lower probability than that of glutamate, and evokes unitary currents about half the amplitude of those mediated through AMPA receptors. Furthermore, the packets of ATP appear to be released from vesicle in a subset of glutamate-containing terminals. PMID:17325196

Pankratov, Yuriy; Lalo, Ulyana; Verkhratsky, Alexei; North, R. Alan

2007-01-01

111

Quantal release of ATP in mouse cortex.  

PubMed

Transient currents occur at rest in cortical neurones that reflect the quantal release of transmitters such as glutamate and gamma-aminobutyric acid (GABA). We found a bimodal amplitude distribution for spontaneously occurring inward currents recorded from mouse pyramidal neurones in situ, in acutely isolated brain slices superfused with picrotoxin. Larger events were blocked by glutamate receptor (AMPA, kainate) antagonists; smaller events were partially inhibited by P2X receptor antagonists suramin and PPADS. The decay of the larger events was selectively prolonged by cyclothiazide. Stimulation of single intracortical axons elicited quantal glutamate-mediated currents and also quantal currents with amplitudes corresponding to the smaller spontaneous inward currents. It is likely that the lower amplitude spontaneous events reflect packaged ATP release. This occurs with a lower probability than that of glutamate, and evokes unitary currents about half the amplitude of those mediated through AMPA receptors. Furthermore, the packets of ATP appear to be released from vesicle in a subset of glutamate-containing terminals. PMID:17325196

Pankratov, Yuriy; Lalo, Ulyana; Verkhratsky, Alexei; North, R Alan

2007-03-01

112

Lab III -1 LABORATORY III  

E-print Network

of every day experience. The gentle ripples in an ocean surface that can become pounding waves on the shoreLab III - 1 LABORATORY III WAVES Mechanical waves allow us to transfer energy from one position to another without actually moving an object between those two positions. Waves are an important part

Minnesota, University of

113

,..._..,..,.,..~I~III:M~III'fi;)IU" ANN ARBOR,MICH "u. Experiment Electrical  

E-print Network

26-Sept-66 ,..._..,..,.,..~I~III:M~III'fi;)IU" ANN ARBOR,MICH "u. ATM-483 Experiment Electrical SYSTIMS DIVISION ANN ARBOR, MICH. Experiment Electrical Interface Definitions Active Seismic Experiment 52-18 Sequential Fire PAGES #12;IINDfX SYSTIMS DIVIIiGM ANN ARBOR, MICH. Experiment Electrical

Rathbun, Julie A.

114

Evidence for the Synthesis of ATP by an F0F1 ATP Synthase in Membrane Vesicles from Halorubrum Saccharovorum  

NASA Technical Reports Server (NTRS)

Vesicles prepared in a buffer containing ADP, Mg(2+) and Pi synthesized ATP at an initial rate of 2 nmols/min/mg protein after acidification of the bulk medium (pH 8 (right arrow) 4). The intravesicular ATP concentration reached a steady state after about 30 seconds and slowly declined thereafter. ATP synthesis was inhibited by low concentrations of dicyclohexylcarbodiimide and m-chlorophenylhydrazone indicating that synthesis took place in response to the proton gradient. NEM and PCMS, which inhibit vacuolar ATPases and the vacuolar-like ATPases of extreme halophiles, did not affect ATP synthesis, and, in fact, produced higher steady state levels of ATP. This suggested that two ATPase activities were present, one which catalyzed ATP synthesis and one that caused its hydrolysis. Azide, a specific inhibitor of F0F1 ATP Synthases, inhibited halobacterial ATP synthesis. The distribution of acridine orange as imposed by a delta pH demonstrated that azide inhibition was not due to the collapse of the proton gradient due to azide acting as a protonophore. Such an effect was observed, but only at azide concentrations higher than those that inhibited ATP synthesis. These results confirm the earler observations with cells of H. saccharovorum and other extreme halophiles that ATP synthesis is inconsistent with the operation of a vacuolar-like ATPase. Therefore, the observation that a vacuolar-like enzyme is responsible for ATP synthesis (and which serves as the basis for imputing ATP synthesis to the vacuolar-like ATPases of the extreme halophiles, and the Archaea in general) should be taken with some degree of caution.

Faguy, David; Lawson, Darion; Hochstein, Lawrence I.; Chang, Sherwood (Technical Monitor)

1996-01-01

115

Monitor III  

SciTech Connect

Monitor III is a totally portable version of the Monitor I and II systems in use at the Clinton P. Anderson Meson Physics Facility (LAMPF) since 1976. The Monitor III system differs from the other systems in that it is capable of operating in any location accessible by truck. Although Monitor III was designed primarily for the handling and disposal of radioactive materials, it is also capable of performing the more sophisticated operations normally performed by the other Monitor systems. The development and operational capabilities of the Monitor remote handling system have been thoroughly reported since 1978. This paper reports on the commissioning of a new system with unique capabilities.

Grisham, D.L.; Lambert, J.E.

1986-01-01

116

ATP synthesis in Halobacterium saccharovorum: evidence that synthesis may be catalysed by an F0F1-ATP synthase  

NASA Technical Reports Server (NTRS)

Halobacterium saccharovorum synthesized ATP in response to a pH shift from 8 to 6.2. Synthesis was inhibited by carbonyl cyanide m-chloro-phenylhydrazone, dicyclohexylcarbodiimide, and azide. Nitrate, an inhibitor of the membrane-bound ATPase previously isolated from this organism, did not inhibit ATP synthesis. N-Ethymaleimide, which also inhibited this ATPase, stimulated the production of ATP. These observations suggested that H. saccharovorum synthesized and hydrolysed ATP using different enzymes and that the vacuolar-like ATPase activity previously described in H. saccharovorum was an ATPase whose function is yet to be identified.

Hochstein, L. I.

1992-01-01

117

Role of phosphate chain mobility of MgATP in completing the 3-phosphoglycerate kinase catalytic site: binding, kinetic, and crystallographic studies with ATP and MgATP.  

PubMed

The complexes of pig muscle 3-phosphoglycerate kinase with the substrate MgATP and with the nonsubstrate Mg(2+)-free ATP have been characterized by binding, kinetic, and crystallographic studies. Comparative experiments with ADP and MgADP have also been carried out. In contrast to the less specific and largely ionic binding of Mg(2+)-free ATP and ADP, specific occupation of the adenosine binding pocket by MgATP and MgADP has been revealed by displacement experiments with adenosine and anions, as well as supported by isothermal calorimetric titrations. The Mg(2+)-free nucleotides similarly stabilize the overall protein structure and restrict the conformational flexibility around the reactive thiol groups of helix 13, as observed by differential scanning microcalorimetry and thiol reactivity studies, respectively. The metal complexes, however, behave differently. MgADP, but not MgATP, further increases the conformational stability with respect to its Mg(2+)-free form, which indicates their different modes of binding to the enzyme. Crystal structures of the binary complexes of the enzyme with MgATP and with ATP (2.1 and 1.9 A resolution, respectively) have shown that the orientation and interaction of phosphates of MgATP largely differ not only from those of ATP but also from the previously determined ones of either MgADP [Davies, G. J., Gamblin, S. J., Littlechild, J. A., Dauter, Z., Wilson, K. S., and Watson, H. C. (1994) Acta Crystallogr. D50, 202-209] or the metal complexes of AMP-PNP [May, A., Vas, M., Harlos, K., and Blake, C. C. F. (1996) Proteins 24, 292-303; Auerbach, G., Huber, R., Grattinger, M., Zaiss, K., Schurig, H., Jaenicke, R., and Jacob, U. (1997) Structure 5, 1475-1483] and are more similar to the interactions formed with MgAMP-PCP [Kovári, Z., Flachner, B., Náray-Szabó, G., and Vas, M. (2002) Biochemistry 41, 8796-8806]. Mg(2+) is liganded to both beta- and gamma-phosphates of ATP, while beta-phosphate is linked to the conserved Asp218, i.e., to the N-terminus of helix 8, through a water molecule; the known interactions of either MgADP or the metal complexes of AMP-PNP with the N-terminus of helix 13 and with Asn336 of beta-strand J are absent in the case of MgATP. Fluctuation of MgATP phosphates between two alternative sites has been proposed to facilitate the correct positioning of the mobile side chain of Lys215, and the catalytically competent active site is thereby completed. PMID:15035615

Flachner, Beáta; Kovári, Zoltán; Varga, Andrea; Gugolya, Zoltán; Vonderviszt, Ferenc; Náray-Szabó, Gábor; Vas, Mária

2004-03-30

118

ATP7A gene addition to the choroid plexus results in long-term rescue of the lethal copper transport defect in a Menkes disease mouse model.  

PubMed

Menkes disease is a lethal infantile neurodegenerative disorder of copper metabolism caused by mutations in a P-type ATPase, ATP7A. Currently available treatment (daily subcutaneous copper injections) is not entirely effective in the majority of affected individuals. The mottled-brindled (mo-br) mouse recapitulates the Menkes phenotype, including abnormal copper transport to the brain owing to mutation in the murine homolog, Atp7a, and dies by 14 days of age. We documented that mo-br mice on C57BL/6 background were not rescued by peripheral copper administration, and used this model to evaluate brain-directed therapies. Neonatal mo-br mice received lateral ventricle injections of either adeno-associated virus serotype 5 (AAV5) harboring a reduced-size human ATP7A (rsATP7A) complementary DNA (cDNA), copper chloride, or both. AAV5-rsATP7A showed selective transduction of choroid plexus epithelia and AAV5-rsATP7A plus copper combination treatment rescued mo-br mice; 86% survived to weaning (21 days), median survival increased to 43 days, 37% lived beyond 100 days, and 22% survived to the study end point (300 days). This synergistic treatment effect correlated with increased brain copper levels, enhanced activity of dopamine-?-hydroxylase, a copper-dependent enzyme, and correction of brain pathology. Our findings provide the first definitive evidence that gene therapy may have clinical utility in the treatment of Menkes disease. PMID:21878905

Donsante, Anthony; Yi, Ling; Zerfas, Patricia M; Brinster, Lauren R; Sullivan, Patricia; Goldstein, David S; Prohaska, Joseph; Centeno, Jose A; Rushing, Elisabeth; Kaler, Stephen G

2011-12-01

119

ATP/P2X7 axis modulates myeloid-derived suppressor cell functions in neuroblastoma microenvironment.  

PubMed

Tumor microenvironment of solid tumors is characterized by a strikingly high concentration of adenosine and ATP. Physiological significance of this biochemical feature is unknown, but it has been suggested that it may affect infiltrating immune cell responses and tumor progression. There is increasing awareness that many of the effects of extracellular ATP on tumor and inflammatory cells are mediated by the P2X7 receptor (P2X7R). Aim of this study was to investigate whether: (i) extracellular ATP is a component of neuroblastoma (NB) microenvironment, (ii) myeloid-derived suppressor cells (MDSCs) express functional P2X7R and (iii) the ATP/P2X7R axis modulates MDSC functions. Our results show that extracellular ATP was detected in NB microenvironment in amounts that increased in parallel with tumor progression. The percentage of CD11b(+)/Gr-1(+) cells was higher in NB-bearing mice compared with healthy animals. Within the CD11b/Gr-1(+) population, monocytic MDSCs (M-MDSCs) produced higher levels of reactive oxygen species (ROS), arginase-1 (ARG-1), transforming growth factor-?1 (TGF-?1) and stimulated more potently in vivo tumor growth, as compared with granulocytic MDSCs (G-MDSCs). P2X7R of M-MDSCs was localized at the plasma membrane, coupled to increased functionality, upregulation of ARG-1, TGF-?1 and ROS. Quite surprisingly, the P2X7R in primary MDSCs as well as in the MSC-1 and MSC-2 lines was uncoupled from cytotoxicity. This study describes a novel scenario in which MDSC immunosuppressive functions are modulated by the ATP-enriched tumor microenvironment. PMID:24651438

Bianchi, G; Vuerich, M; Pellegatti, P; Marimpietri, D; Emionite, L; Marigo, I; Bronte, V; Di Virgilio, F; Pistoia, V; Raffaghello, L

2014-01-01

120

ATP-Driven Molecular Chaperone Machines  

PubMed Central

This review is focused on the mechanisms by which ATP binding and hydrolysis drive chaperone machines assisting protein folding and unfolding. A survey of the key, general chaperone systems Hsp70 and Hsp90, and the unfoldase Hsp100 is followed by a focus on the Hsp60 chaperonin machine which is understood in most detail. Cryo-electron microscopy analysis of the E. coli Hsp60 GroEL reveals intermediate conformations in the ATPase cycle and in substrate folding. These structures suggest a mechanism by which GroEL can forcefully unfold and then encapsulate substrates for subsequent folding in isolation from all other binding surfaces. © 2013 Wiley Periodicals, Inc. Biopolymers 99: 846–859, 2013. PMID:23877967

Clare, Daniel K; Saibil, Helen R

2013-01-01

121

Modelling the ATP production in mitochondria  

E-print Network

We revisit here the mathematical model for ATP production in mitochondria introduced recently by Bertram, Pedersen, Luciani, and Sherman (BPLS) as a simplification of the more complete but intricate Magnus and Keizer's model. We correct some inaccuracies in the BPLS original approximations and then analyze some of the dynamical properties of the model. We infer from exhaustive numerical explorations that the enhanced BPLS equations have a unique attractor fixed point for physiologically acceptable ranges of mitochondrial variables and respiration inputs. We determine, in the stationary regime, the dependence of the mitochondrial variables on the respiration inputs, namely the cytosolic concentration of calcium ${\\rm Ca}_{\\rm c}$ and the substrate fructose 1,6-bisphosphate FBP. The same effect of calcium saturation reported for the original BPLS model is observed here. We find out, however, an interesting non-stationary effect: the inertia of the model tends to increase considerably for high concentrations of ...

Saa, Alberto

2012-01-01

122

ATP11B mediates platinum resistance in ovarian cancer.  

PubMed

Platinum compounds display clinical activity against a wide variety of solid tumors; however, resistance to these agents is a major limitation in cancer therapy. Reduced platinum uptake and increased platinum export are examples of resistance mechanisms that limit the extent of DNA damage. Here, we report the discovery and characterization of the role of ATP11B, a P-type ATPase membrane protein, in cisplatin resistance. We found that ATP11B expression was correlated with higher tumor grade in human ovarian cancer samples and with cisplatin resistance in human ovarian cancer cell lines. ATP11B gene silencing restored the sensitivity of ovarian cancer cell lines to cisplatin in vitro. Combined therapy of cisplatin and ATP11B-targeted siRNA significantly decreased cancer growth in mice bearing ovarian tumors derived from cisplatin-sensitive and -resistant cells. In vitro mechanistic studies on cellular platinum content and cisplatin efflux kinetics indicated that ATP11B enhances the export of cisplatin from cells. The colocalization of ATP11B with fluorescent cisplatin and with vesicular trafficking proteins, such as syntaxin-6 (STX6) and vesicular-associated membrane protein 4 (VAMP4), strongly suggests that ATP11B contributes to secretory vesicular transport of cisplatin from Golgi to plasma membrane. In conclusion, inhibition of ATP11B expression could serve as a therapeutic strategy to overcome cisplatin resistance. PMID:23585472

Moreno-Smith, Myrthala; Halder, J B; Meltzer, Paul S; Gonda, Tamas A; Mangala, Lingegowda S; Rupaimoole, Rajesha; Lu, Chunhua; Nagaraja, Archana S; Gharpure, Kshipra M; Kang, Yu; Rodriguez-Aguayo, Cristian; Vivas-Mejia, Pablo E; Zand, Behrouz; Schmandt, Rosemarie; Wang, Hua; Langley, Robert R; Jennings, Nicholas B; Ivan, Cristina; Coffin, Jeremy E; Armaiz, Guillermo N; Bottsford-Miller, Justin; Kim, Sang Bae; Halleck, Margaret S; Hendrix, Mary J C; Bornman, William; Bar-Eli, Menashe; Lee, Ju-Seog; Siddik, Zahid H; Lopez-Berestein, Gabriel; Sood, Anil K

2013-05-01

123

ATP11B mediates platinum resistance in ovarian cancer  

PubMed Central

Platinum compounds display clinical activity against a wide variety of solid tumors; however, resistance to these agents is a major limitation in cancer therapy. Reduced platinum uptake and increased platinum export are examples of resistance mechanisms that limit the extent of DNA damage. Here, we report the discovery and characterization of the role of ATP11B, a P-type ATPase membrane protein, in cisplatin resistance. We found that ATP11B expression was correlated with higher tumor grade in human ovarian cancer samples and with cisplatin resistance in human ovarian cancer cell lines. ATP11B gene silencing restored the sensitivity of ovarian cancer cell lines to cisplatin in vitro. Combined therapy of cisplatin and ATP11B-targeted siRNA significantly decreased cancer growth in mice bearing ovarian tumors derived from cisplatin-sensitive and -resistant cells. In vitro mechanistic studies on cellular platinum content and cisplatin efflux kinetics indicated that ATP11B enhances the export of cisplatin from cells. The colocalization of ATP11B with fluorescent cisplatin and with vesicular trafficking proteins, such as syntaxin-6 (STX6) and vesicular-associated membrane protein 4 (VAMP4), strongly suggests that ATP11B contributes to secretory vesicular transport of cisplatin from Golgi to plasma membrane. In conclusion, inhibition of ATP11B expression could serve as a therapeutic strategy to overcome cisplatin resistance. PMID:23585472

Moreno-Smith, Myrthala; Halder, J.B.; Meltzer, Paul S.; Gonda, Tamas A.; Mangala, Lingegowda S.; Rupaimoole, Rajesha; Lu, Chunhua; Nagaraja, Archana S.; Gharpure, Kshipra M.; Kang, Yu; Rodriguez-Aguayo, Cristian; Vivas-Mejia, Pablo E.; Zand, Behrouz; Schmandt, Rosemarie; Wang, Hua; Langley, Robert R.; Jennings, Nicholas B.; Ivan, Cristina; Coffin, Jeremy E.; Armaiz, Guillermo N.; Bottsford-Miller, Justin; Kim, Sang Bae; Halleck, Margaret S.; Hendrix, Mary J.C.; Bornman, William; Bar-Eli, Menashe; Lee, Ju-Seog; Siddik, Zahid H.; Lopez-Berestein, Gabriel; Sood, Anil K.

2013-01-01

124

ATP content in the rat brain during stress  

Microsoft Academic Search

The total corticosterone content in the peripheral blood and ATP content in the brain of albino rats were studied after laparotomy and immobilization for various periods. The cortieosterone concentration rose sharply in response to stress and reached its maximum before the appearance of the first signs of Selye's triad. The ATP content in the brain fell considerably during both types

V. V. Rozhanets; E. G. Gavrishchuk; I. M. Rodionov; A. G. Volchek; I. S. Kulaev

1974-01-01

125

Synphilin-1 binds ATP and regulates intracellular energy status.  

PubMed

Recent studies have suggested that synphilin-1, a cytoplasmic protein, is involved in energy homeostasis. Overexpression of synphilin-1 in neurons results in hyperphagia and obesity in animal models. However, the mechanism by which synphilin-1 alters energy homeostasis is unknown. Here, we used cell models and biochemical approaches to investigate the cellular functions of synphilin-1 that may affect energy balance. Synphilin-1 was pulled down by ATP-agarose beads, and the addition of ATP and ADP reduced this binding, indicating that synphilin-1 bound ADP and ATP. Synphilin-1 also bound GMP, GDP, and GTP but with a lower affinity than it bound ATP. In contrast, synphilin-1 did not bind with CTP. Overexpression of synphilin-1 in HEK293T cells significantly increased cellular ATP levels. Genetic alteration to abolish predicted ATP binding motifs of synphilin-1 or knockdown of synphilin-1 by siRNA reduced cellular ATP levels. Together, these data demonstrate that synphilin-1 binds and regulates the cellular energy molecule, ATP. These findings provide a molecular basis for understanding the actions of synphilin-1 in energy homeostasis. PMID:25545246

Li, Tianxia; Liu, Jingnan; Smith, Wanli W

2014-01-01

126

Synphilin-1 Binds ATP and Regulates Intracellular Energy Status  

PubMed Central

Recent studies have suggested that synphilin-1, a cytoplasmic protein, is involved in energy homeostasis. Overexpression of synphilin-1 in neurons results in hyperphagia and obesity in animal models. However, the mechanism by which synphilin-1 alters energy homeostasis is unknown. Here, we used cell models and biochemical approaches to investigate the cellular functions of synphilin-1 that may affect energy balance. Synphilin-1 was pulled down by ATP-agarose beads, and the addition of ATP and ADP reduced this binding, indicating that synphilin-1 bound ADP and ATP. Synphilin-1 also bound GMP, GDP, and GTP but with a lower affinity than it bound ATP. In contrast, synphilin-1 did not bind with CTP. Overexpression of synphilin-1 in HEK293T cells significantly increased cellular ATP levels. Genetic alteration to abolish predicted ATP binding motifs of synphilin-1 or knockdown of synphilin-1 by siRNA reduced cellular ATP levels. Together, these data demonstrate that synphilin-1 binds and regulates the cellular energy molecule, ATP. These findings provide a molecular basis for understanding the actions of synphilin-1 in energy homeostasis. PMID:25545246

Li, Tianxia; Liu, Jingnan; Smith, Wanli W.

2014-01-01

127

The Dark Side of Extracellular ATP in Kidney Diseases.  

PubMed

Intracellular ATP is the most vital source of cellular energy for biologic systems, whereas extracellular ATP is a multifaceted mediator of several cell functions via its interaction, in an autocrine or paracrine manner, with P2 purinergic receptors expressed on the cell surface. These ionotropic and metabotropic P2 purinergic receptors modulate a variety of physiologic events upon the maintenance of a highly sensitive "set point," the derangement of which may lead to the development of key pathogenic mechanisms during acute and chronic diseases. Growing evidence suggests that extracellular ATP signaling via P2 purinergic receptors may be involved in different renal pathologic conditions. For these reasons, investigators and pharmaceutical companies are actively exploring novel strategies to antagonize or block these receptors with the goal of reducing extracellular ATP production or accelerating extracellular ATP clearance. Targeting extracellular ATP signaling, particularly through the P2X7 receptor, has considerable translational potential, given that novel P2X7-receptor inhibitors are already available for clinical use (e.g., CE224,535, AZD9056, and GSK1482160). This review summarizes the current evidence regarding the involvement of extracellular ATP and its P2 purinergic receptor-mediated signaling in physiologic and pathologic processes in the kidney; potential therapeutic options targeting extracellular ATP purinergic receptors are analyzed as well. PMID:25452669

Solini, Anna; Usuelli, Vera; Fiorina, Paolo

2014-12-01

128

ATP Synthase: Two rotary molecular motors working together  

E-print Network

this in a surprising way: by converting the electromotive force into a rotary torque that is used to promote phosphate binding and to liberate ATP from the catalytic site where it was formed. Remarkably, this process can to F1: ge and b2d. The key to understanding how ATP synthase carries out its catalytic and synthetic

Wang, Hongyun

129

Mechanism of ATP loss in nonoxidative contracting muscle  

NSDL National Science Digital Library

The transition from rest to intense exercise is a challenge to cellular energetics (11, 13, 15). The metabolic fuels, i.e., the sources of ATP to sustain muscular contraction, are creatine phosphate and glycogen. Two anaerobic metabolic paths, leading to ATP generation, are catalyzed by creatine kinase and by the 12 enzymes of nonoxidative glycolysis, starting from glycogen. There is now general agreement that, unless replenished, creatine phosphate can sustain heavy muscle contraction for only 3Â?4 s. Thereafter, nonoxidative glycolysis becomes the main ATP source, until the onset of fatigue. This article aimed to relate the path of ATP generation during glycogen utilization as a metabolic fuel with that of ATP breakdown in nonoxidative contracting muscle.

2011-03-01

130

ATP mediates excitatory synaptic transmission in mammalian neurones.  

PubMed Central

Adenosine 5'-triphosphate (ATP, 0.1-100 microM), produced inward currents in patch-clamped coeliac neurones from guinea-pig when studied in either the whole cell configuration or in excised (outside-out) patches. The P2-purinoceptor antagonists suramin (80-230 microM) or reactive blue 2 (2-20 microM) depressed the ATP-induced currents but not those produced by acetylcholine. Excitatory post-synaptic currents (e.p.s.cs) were observed in cultured neurones. E.p.s.cs had similar current-voltage relationships to currents evoked by ATP in excised patches and were reduced by suramin or reactive blue 2 to a similar extent as ATP currents. The results suggest that ATP is the excitatory neurotransmitter in cultures of these neurones. PMID:1327385

Silinsky, E. M.; Gerzanich, V.; Vanner, S. M.

1992-01-01

131

Novel mitochondrial mutations in the ATP6 and ATP8 genes in patients with breast cancer.  

PubMed

The role of the mitochondria in the process of carcinogenesis, mainly oxidative phosphorylation, mostly concerns their participation in the production of free radicals and ATP and in the process of apoptosis. The purpose of this study was to detect potential changes in the genes encoding the subunits 6 and 8 of the ATP synthase and their impact on the enzyme's biochemical properties, structure and function in patients with breast tumors. The tested material was mitochondrial DNA (mtDNA) isolated from specimens of ductal carcinoma (carcinoma ductale) Tp1-2Np0-1Mp0, blood and non-cancerous tissue of mammary gland (control), sampled from 50 patients who had been operated for breast cancer. In the case of missense-type changes in the mtDNA, protein prediction software was used to assess their effect on the biochemical properties of the protein, its structure and function. We identified 8 changes in the ATP6 gene in 36/50 examined breast cancer cell samples and 5 changes in the ATP8 gene (10/50). Most of them were homoplasmic changes of missense type. Four of the changes (A8439C, G8858C, C9130G and T9119G) had not been described in the literature before. The identified mutations and polymorphisms, especially those of missense type, can affect mitochondrial functions, especially if the conservative domain of the protein is concerned. Replacement of 'wild-type' mtDNA by mutated mtDNA can be an important event in carcinogenesis. PMID:25110199

Grzybowska-Szatkowska, Ludmi?a; Slaska, Brygida; Rzymowska, Jolanta; Brzozowska, Anna; Floria?czyk, Boles?aw

2014-10-01

132

Performance and Specificity of the Covalently Linked Immunomagnetic Separation-ATP Method for Rapid Detection and Enumeration of Enterococci in Coastal Environments  

PubMed Central

The performance and specificity of the covalently linked immunomagnetic separation-ATP (Cov-IMS/ATP) method for the detection and enumeration of enterococci was evaluated in recreational waters. Cov-IMS/ATP performance was compared with standard methods: defined substrate technology (Enterolert; IDEXX Laboratories), membrane filtration (EPA Method 1600), and an Enterococcus-specific quantitative PCR (qPCR) assay (EPA Method A). We extend previous studies by (i) analyzing the stability of the relationship between the Cov-IMS/ATP method and culture-based methods at different field sites, (ii) evaluating specificity of the assay for seven ATCC Enterococcus species, (iii) identifying cross-reacting organisms binding the antibody-bead complexes with 16S rRNA gene sequencing and evaluating specificity of the assay to five nonenterococcus species, and (iv) conducting preliminary tests of preabsorption as a means of improving the assay. Cov-IMS/ATP was found to perform consistently and with strong agreement rates (based on exceedance/compliance with regulatory limits) of between 83% and 100% compared to the culture-based Enterolert method at a variety of sites with complex inputs. The Cov-IMS/ATP method is specific to five of seven different Enterococcus spp. tested. However, there is potential for nontarget bacteria to bind the antibody, which may be reduced by purification of the IgG serum with preabsorption at problematic sites. The findings of this study help to validate the Cov-IMS/ATP method, suggesting a predictable relationship between the Cov-IMS/ATP method and traditional culture-based methods, which will allow for more widespread application of this rapid and field-portable method for coastal water quality assessment. PMID:24561583

Zimmer-Faust, Amity G.; Thulsiraj, Vanessa; Ferguson, Donna

2014-01-01

133

Functional proteomics of synaptic plasma membrane ATP-ases of rat hippocampus: Effect of l-acetylcarnitine and relationships with Dementia and Depression pathophysiology.  

PubMed

Synaptic energy state and mitochondrial dysfunction are crucial factors in many brain pathologies. l-acetylcarnitine, a natural derivative of carnitine, improves brain energy metabolism, and has been proposed for the Therapy of many neurological and psychiatric diseases. The effects of the drug on the maximum rate (Vmax) of enzymatic activities related to hippocampal synaptic energy utilization were evaluated, in the perspective of its employment for Dementias and Depression Therapy. Two types of synaptic plasma membranes (SPM1 and SPM2) were isolated from the hippocampus of rats treated with l-acetylcarnitine (30 and 60mg/kg i.p., 28 days, 5 days/week). Acetylcholinesterase (AChE); Na(+), K(+), Mg(2+)-ATP-ase; ouabain-insensitive Mg(2+)-ATP-ase; Na(+), K(+)-ATP-ase; Ca(2+), Mg(2+)-ATP-ase activities were evaluated. In control animals, enzymatic activities were differently expressed in SPM1 , being the evaluated enzymatic activities higher in SPM2. Subchronic treatment with l-acetylcarnitine (i) did not modify AChE on both SPMs; (ii) increased Na(+), K(+), Mg(2+)-ATP-ase, ouabain-insensitive Mg(2+)-ATP-ase and Na(+), K(+)-ATP-ase at the dose of 30 and 60mg/kg on SPM1 and SPM2; (iii) increased Ca(2+), Mg(2+)-ATP-ase activity on both SPMs at the dose of 60mg/kg. These results have been discussed considering the pathophysiology and treatment of Dementias and Depression because, although referred to normal healthy animals, they support the notion that l-acetylcarnitine may have positive effects in these pathologies. PMID:25797282

Ferrari, Federica; Gorini, Antonella; Villa, Roberto Federico

2015-06-01

134

15 CFR 295.11 - Technical and educational services for ATP recipients.  

Code of Federal Regulations, 2010 CFR

... Technical and educational services for ATP recipients. 295.11 Section 295... Technical and educational services for ATP recipients. (a) Under the...Technology. (c) From time to time, ATP may conduct public workshops and...

2010-01-01

135

75 FR 8467 - Airworthiness Directives; BAE SYSTEMS (Operations) Limited Model ATP Airplanes  

Federal Register 2010, 2011, 2012, 2013, 2014

...BAE SYSTEMS (Operations) Limited Model ATP Airplanes AGENCY: Federal Aviation Administration...were introduced by Service Bulletin (SB) ATP-51-002 * * *. As it was determined...were introduced by Service Bulletin (SB) ATP-51- 002, which supplemented and in...

2010-02-25

136

Kinetic and Stability Properties of Penicillium chrysogenum ATP Sulfurylase Missing the C-terminal Regulatory Domain*  

E-print Network

Kinetic and Stability Properties of Penicillium chrysogenum ATP Sulfurylase Missing the C 95616 ATP sulfurylase from Penicillium chrysogenum is a homohexameric enzyme that is subject kinase) REACTIONS 1 AND 2 ATP sulfurylase from the filamentous fungus, Penicillium chrysogenum

Fisher, Andrew J.

137

Slow dissociation of ATP from the calcium ATPase.  

PubMed

The acyl-phosphate intermediate of the sarcoplasmic reticulum calcium ATPase reaction, formed in a brief incubation of vesicular enzyme with 5 microM [gamma-32P]ATP and calcium, reacts biphasically with added ADP (pH 7.0, 25 degrees C, 100 mM KCl, 5 mM MgSO4). Both the burst size and the rate constant for the slow phase increase with increasing ADP concentration in the way that is expected if the burst represents very rapid formation of an equilibrium amount of enzyme-bound ATP and the slow phase represents rate-limiting dissociation of ATP. Also consistent with this interpretation are the slow labeling of phosphoenzyme under conditions in which unlabeled ATP must dissociate first and the observation of a burst of ATP formation on ADP addition to phosphoenzyme. Values of the equilibrium constants for ADP dissociation from phosphoenzyme (0.75 mM), for ATP formation on the enzyme (2.3), and for the ATP dissociation rate constant (37 s-1) were obtained from a quantitative analysis of the data. PMID:6461647

Pickart, C M; Jencks, W P

1982-05-25

138

The Chloroplast ATP Synthase Features the Characteristic Redox Regulation Machinery  

PubMed Central

Abstract Significance: Regulation of the activity of the chloroplast ATP synthase is largely accomplished by the chloroplast thioredoxin system, the main redox regulation system in chloroplasts, which is directly coupled to the photosynthetic reaction. We review the current understanding of the redox regulation system of the chloroplast ATP synthase. Recent Advances: The thioredoxin-targeted portion of the ATP synthase consists of two cysteines located on the central axis subunit ?. The redox state of these two cysteines is under the influence of chloroplast thioredoxin, which directly controls rotation during catalysis by inducing a conformational change in this subunit. The molecular mechanism of redox regulation of the chloroplast ATP synthase has recently been determined. Critical Issues: Regulation of the activity of the chloroplast ATP synthase is critical in driving efficiency into the ATP synthesis reaction in chloroplasts. Future Directions: The molecular architecture of the chloroplast ATP synthase, which confers redox regulatory properties requires further investigation, in light of the molecular structure of the enzyme complex as well as the physiological significance of the regulation system. Antioxid. Redox Signal. 19, 1846–1854. PMID:23145525

Sunamura, Ei-Ichiro; Kim, Yusung; Konno, Hiroki

2013-01-01

139

ATP requirement for acidic resistance in Escherichia coli.  

PubMed

ATP participates in many cellular metabolic processes as a major substrate to supply energy. Many systems for acidic resistance (AR) under extremely acidic conditions have been reported, but the role of ATP has not been examined. To clarify whether or not ATP is necessary for the AR in Escherichia coli, the AR of mutants deficient in genes for ATP biosynthesis was investigated in this study. The deletion of purA or purB, each of which encodes enzymes to produce AMP from inosinate (IMP), markedly decreased the AR. The content of ATP in these mutants decreased rapidly at pH 2.5 compared to that of the wild type. The AR was again decreased significantly by the mutation of adk, which encoded an enzyme to produce ADP from AMP. The DNA damage in the purA and purB mutants was higher than that in the wild type. These results demonstrated that metabolic processes that require ATP participate in survival under extremely acidic conditions, and that one such system is the ATP-dependent DNA repair system. PMID:21478347

Sun, Yirong; Fukamachi, Toshihiko; Saito, Hiromi; Kobayashi, Hiroshi

2011-06-01

140

ATP and potassium ions: a deadly combination for astrocytes  

NASA Astrophysics Data System (ADS)

The ATP release channel Pannexin1 (Panx1) is self-regulated, i.e. the permeant ATP inhibits the channel from the extracellular space. The affinity of the ATP binding site is lower than that of the purinergic P2X7 receptor allowing a transient activation of Panx1 by ATP through P2X7R. Here we show that the inhibition of Panx1 by ATP is abrogated by increased extracellular potassium ion concentration ([K+]o) in a dose-dependent manner. Since increased [K+]o is also a stimulus for Panx1 channels, it can be expected that a combination of ATP and increased [K+]o would be deadly for cells. Indeed, astrocytes did not survive exposure to these combined stimuli. The death mechanism, although involving P2X7R, does not appear to strictly follow a pyroptotic pathway. Instead, caspase-3 was activated, a process inhibited by Panx1 inhibitors. These data suggest that Panx1 plays an early role in the cell death signaling pathway involving ATP and K+ ions. Additionally, Panx1 may play a second role once cells are committed to apoptosis, since Panx1 is also a substrate of caspase-3.

Jackson, David G.; Wang, Junjie; Keane, Robert W.; Scemes, Eliana; Dahl, Gerhard

2014-04-01

141

Allosteric modulation of GABAA receptors by extracellular ATP  

PubMed Central

Background The ?-aminobutyric acid type A receptor (GABAAR) is the primary receptor mediating fast synaptic inhibition in the brain and plays a critical role in modulation of neuronal excitability and neural networks. Previous studies have demonstrated that ATP and its nucleotide analogs may regulate the function of GABAARs via Ca2+-dependent intracellular mechanisms, which require activation of purinergic 2 (P2) receptors or cross-talk between two receptors. Results Here, we report a potentiation of GABAARs by extracellular ATP via a previously un-recognized allosteric mechanism. Using cultured hippocampal neurons as well as HEK293 cells transiently expressing GABAARs, we demonstrate that extracellular ATP potentiates GABAAR mediated currents in a dose-dependent manner with an EC50 of 2.1?±?0.2 mM. The potentiation was mediated by a postsynaptic mechanism that was not dependent on activation of either ecto-protein kinase or P2 receptors. Single channel recordings from cell-free excised membrane patches under outside-out mode or isolated membrane patches under cell-attached mode suggest that the ATP modulation of GABA currents is achieved through a direct action of ATP on the channels themselves and manifested by increasing the single channel open probability without alteration of its conductance. Moreover, this ATP potentiation of GABAAR could be reconstituted in HEK293 cells that transiently expressed recombinant rat GABAARs. Conclusions Our data strongly suggest that extracellular ATP allosterically potentiates GABAAR-gated chloride channels. This novel mode of ATP-mediated modulation of GABAARs may play an important role in regulating neuronal excitability and thereby in fine-tuning the excitation-inhibition balance under conditions where a high level of extracellular ATP is ensured. PMID:24456563

2014-01-01

142

Kinetics of electrogenic transport by the ADP/ATP carrier.  

PubMed Central

The electrogenic transport of ATP and ADP by the mitochondrial ADP/ATP carrier (AAC) was investigated by recording transient currents with two different techniques for performing concentration jump experiments: 1) the fast fluid injection method: AAC-containing proteoliposomes were adsorbed to a solid supported membrane (SSM), and the carrier was activated via ATP or ADP concentration jumps. 2) BLM (black lipid membrane) technique: proteoliposomes were adsorbed to a planar lipid bilayer, while the carrier was activated via the photolysis of caged ATP or caged ADP with a UV laser pulse. Two transport modes of the AAC were investigated, ATP(ex)-0(in) and ADP(ex)-0(in). Liposomes not loaded with nucleotides allowed half-cycles of the ADP/ATP exchange to be studied. Under these conditions the AAC transports ADP and ATP electrogenically. Mg(2+) inhibits the nucleotide transport, and the specific inhibitors carboxyatractylate (CAT) and bongkrekate (BKA) prevent the binding of the substrate. The evaluation of the transient currents yielded rate constants of 160 s(-1) for ATP and >/=400 s(-1) for ADP translocation. The function of the carrier is approximately symmetrical, i.e., the kinetic properties are similar in the inside-out and right-side-out orientations. The assumption from previous investigations, that the deprotonated nucleotides are exclusively transported by the AAC, is supported by further experimental evidence. In addition, caged ATP and caged ADP bind to the carrier with similar affinities as the free nucleotides. An inhibitory effect of anions (200-300 mM) was observed, which can be explained as a competitive effect at the binding site. The results are summarized in a transport model. PMID:10423420

Gropp, T; Brustovetsky, N; Klingenberg, M; Müller, V; Fendler, K; Bamberg, E

1999-01-01

143

Quantal release of ATP from clusters of PC12 cells  

PubMed Central

Although ATP is important for intercellular communication, little is known about the mechanism of endogenous ATP release due to a dearth of suitable models. Using PC12 cells known to express the P2X2 subtype of ATP receptors and to store ATP with catecholamines inside dense-core vesicles, we found that clusters of PC12 cells cultured for 3–7 days generated small transient inward currents (STICs) after an inward current elicited by exogenous ATP. The amplitude of STICs in individual cells correlated with the peak amplitude of ATP-induced currents. STICs appeared as asynchronous responses (approximately 20 pA average amplitude) for 1–20 s and were investigated with a combination of patch clamping, Ca2+ imaging, biochemistry and electron microscopy. Comparable STICs were produced by focal KCl pulses and were dependent on extracellular Ca2+. STICs were abolished by the P2X antagonist PPADS and potentiated by Zn2+, suggesting they were mediated by P2X2 receptor activation. The highest probability of observing STICs was after the peak of intracellular Ca2+ increase caused by KCl. Biochemical measurements indicated that KCl application induced a significant release of ATP from PC12 cells. Electron microscopy studies showed narrow clefts without ‘synaptic-like’ densities between clustered cells. Our data suggest that STICs were caused by quantal release of endogenous ATP by depolarized PC12 cells in close juxtaposition to the recorded cell. Thus, STICs may be a new experimental model to characterize the physiology of vesicular release of ATP and to study the kinetics and pharmacology of P2X2 receptor-mediated quantal currents. PMID:15331685

Fabbro, Alessandra; Skorinkin, Andrei; Grandolfo, Micaela; Nistri, Andrea; Giniatullin, Rashid

2004-01-01

144

Structure and expression of the atp operon coding for F1F0-ATP synthase from the antibiotic-producing actinomycete Nonomuraea sp. ATCC 39727.  

PubMed

Nonomuraea sp. ATCC 39727 is a poorly characterized actinomycete, producer of the glycopeptide antibiotic A40926. In this study, the nucleotide sequence of the atp operon coding for F1F0-ATP synthase of Nonomuraea sp. ATCC 39727 was determined. It consisted of ten open reading frames arranged in the order atpI (encoding the i protein), orfX, atpB (a subunit), atpE (c subunit), atpF (b subunit), atpH (delta subunit), atpA (alpha subunit), atpG (gamma subunit), atpD (beta subunit) and atpC (epsilon subunit). The orfX coded for a putative small hydrophobic 71 amino acid peptide of unknown function related to several bacterial permeases. Its presence appeared to be a distinctive feature of the atp operon of phylogenetically distant actinobacteria. Transcription of the atp operon was evaluated. The results of northern blot and RT-PCR experiments demonstrated that the atp genes were co-transcribed into a single polycistronic mRNA. Real-time RT-PCR data provided evidence showing that transcription of the atp operon was biphasic during Nonomuraea growth. The amount of the atpD transcript decreased at the end of the exponential growth phase, and then moderately increased during the early stationary phase when, in contrast, the levels of ctaC, encoding the cytochrome c oxidase subunit II, progressively decreased. Western blot analysis confirmed that ATP synthase was also present in the membrane during the stationary phase. These results together with previous data demonstrate that oligomycin-sensitive ATP-driven proton pumping activity remained constant in the stationary phase; in contrast, the activity and cytochrome content of the respiratory enzymes became negligible. PMID:16545948

Gaballo, Antonio; Abbrescia, Anna; Palese, Luigi L; Micelli, Loris; di Summa, Roberta; Alifano, Pietro; Papa, Sergio

2006-09-01

145

LANDVIEW III  

EPA Science Inventory

LandView III is a desktop mapping system that includes database extracts from the Environmental Protection Agency, the Bureau of the Census, The U.S. Geological Survey, the Nuclear Regulatory Commission, the Department of Transportation, and the Federal Emergency Management Agenc...

146

Welding III.  

ERIC Educational Resources Information Center

Instructional objectives and performance requirements are outlined in this course guide for Welding III, an advanced course in arc welding offered at the Community College of Allegheny County to provide students with the proficiency necessary for industrial certification. The course objectives, which are outlined first, specify that students will…

Allegheny County Community Coll., Pittsburgh, PA.

147

Regulation of ATP production by mitochondrial Ca2+  

PubMed Central

Stimulation of mitochondrial oxidative metabolism by Ca2+ is now generally recognised as important for the control of cellular ATP homeostasis. Here, we review the mechanisms through which Ca2+ regulates mitochondrial ATP synthesis. We focus on cardiac myocytes and pancreatic ?-cells, where tight control of this process is likely to play an important role in the response to rapid changes in workload and to nutrient stimulation, respectively. We also describe a novel approach for imaging the Ca2+-dependent regulation of ATP levels dynamically in single cells. PMID:22502861

Tarasov, Andrei I.; Griffiths, Elinor J.; Rutter, Guy A.

2012-01-01

148

Twisting and subunit rotation in single FOF1-ATP synthase  

PubMed Central

FOF1-ATP synthases are ubiquitous proton- or ion-powered membrane enzymes providing ATP for all kinds of cellular processes. The mechanochemistry of catalysis is driven by two rotary nanomotors coupled within the enzyme. Their different step sizes have been observed by single-molecule microscopy including videomicroscopy of fluctuating nanobeads attached to single enzymes and single-molecule Förster resonance energy transfer. Here we review recent developments of approaches to monitor the step size of subunit rotation and the transient elastic energy storage mechanism in single FOF1-ATP synthases. PMID:23267178

Sielaff, Hendrik; Börsch, Michael

2013-01-01

149

Preparation and configurational analysis of the stereoisomers of /beta/,/gamma/-bidentate Rh(H/sub 2/O)/sub 4/ATP and /alpha/,/beta/,/gamma/-tridentate Rh(H/sub 2/O)/sub 3/ATP. A new class of enzyme active site probes  

SciTech Connect

Exchange-inert Co(III) and Cr(III) complexes of polyphosphates have proved to be useful probes of the structural and biochemical properties of naturally occurring Mg/sup II/(polyphosphate) complexes. However, applications of these complexes are not without limitations. The Cr/sup III/(polyphosphate) probes or their enzymatic products cannot be used in NMR methods because of the paramagnetic nature of the Cr(III) metal. The redox properties of the metal in the Co/sup III/(polyphosphate) complexes require that they also be coordinated to a nitrogen-containing ligand. This requirement is not always convenient. This work reported herein was undertaken to create a new class of exchange-inert metal polyphosphate complexes that contain a metal that is both diamagnetic and redox stable. The preparation, properties, and configurational analysis of the stereoisomers of /beta/, /gamma/-bidentate Rh(H/sub 2/O)/sub 4/ATP (ATP = adenosine 5'-triphosphate) and /alpha/,/beta/,/gamma/-tridentate Rh(H/sub 2/O)/sub 3/ATP are described. 12 refs., 5 figs.

Lu, Z.; Shorter, A.L.; Lin, I.; Dunaway-Mariano, D.

1988-11-16

150

Inhibitors of the 5-lipoxygenase arachidonic acid pathway induce ATP release and ATP-dependent organic cation transport in macrophages.  

PubMed

We have previously described that arachidonic acid (AA)-5-lipoxygenase (5-LO) metabolism inhibitors such as NDGA and MK886, inhibit cell death by apoptosis, but not by necrosis, induced by extracellular ATP (ATPe) binding to P2X7 receptors in macrophages. ATPe binding to P2X7 also induces large cationic and anionic organic molecules uptake in these cells, a process that involves at least two distinct transport mechanisms: one for cations and another for anions. Here we show that inhibitors of the AA-5-LO pathway do not inhibit P2X7 receptors, as judged by the maintenance of the ATPe-induced uptake of fluorescent anionic dyes. In addition, we describe two new transport phenomena induced by these inhibitors in macrophages: a cation-selective uptake of fluorescent dyes and the release of ATP. The cation uptake requires secreted ATPe, but, differently from the P2X7/ATPe-induced phenomena, it is also present in macrophages derived from mice deficient in the P2X7 gene. Inhibitors of phospholipase A2 and of the AA-cyclooxygenase pathway did not induce the cation uptake. The uptake of non-organic cations was investigated by measuring the free intracellular Ca(2+) concentration ([Ca(2+)]i) by Fura-2 fluorescence. NDGA, but not MK886, induced an increase in [Ca(2+)]i. Chelating Ca(2+) ions in the extracellular medium suppressed the intracellular Ca(2+) signal without interfering in the uptake of cationic dyes. We conclude that inhibitors of the AA-5-LO pathway do not block P2X7 receptors, trigger the release of ATP, and induce an ATP-dependent uptake of organic cations by a Ca(2+)- and P2X7-independent transport mechanism in macrophages. PMID:24743022

da Silva-Souza, Hercules Antônio; Lira, Maria Nathalia de; Costa-Junior, Helio Miranda; da Cruz, Cristiane Monteiro; Vasconcellos, Jorge Silvio Silva; Mendes, Anderson Nogueira; Pimenta-Reis, Gabriela; Alvarez, Cora Lilia; Faccioli, Lucia Helena; Serezani, Carlos Henrique; Schachter, Julieta; Persechini, Pedro Muanis

2014-07-01

151

The rate of production of uric acid by hepatocytes is a sensitive index of compromised cell ATP homeostasis.  

PubMed

Plasma levels of uric acid, the final product of purine degradation in humans, are elevated in metabolic syndrome and are strongly associated with insulin resistance and nonalcoholic fatty liver disease (NAFLD). Hepatic and blood levels of purine metabolites (inosine, hypoxanthine, and xanthine) are also altered in pathophysiological states. We optimized a rat hepatocyte model to test the hypothesis that the production of uric acid by hepatocytes is a potential marker of compromised homeostasis of hepatocellular inorganic phosphate (Pi) and/or ATP. The basal rate of uric acid production from endogenous substrates in rat hepatocytes was comparable to that in human liver and was <10% of the maximum rate with saturating concentrations of purine substrates. It was marginally (~20%) decreased by insulin and increased by glucagon but was stimulated more than twofold by substrates (fructose and glycerol) that lower both cell ATP and Pi, and by inhibitors of mitochondrial respiration (complexes I, III, and V) that lower ATP but raise cell Pi. Clearance of inosine and its degradation to uric acid were also inhibited by cell Pi depletion. Analysis of gene expression in NAFLD biopsies showed an association between mRNA expression of GCKR, the glucokinase regulatory protein that is functionally linked to uric acid production, and mRNA expression of the phosphate transporters encoded by SLC17A1/3. Uric acid production by hepatocytes is a very sensitive index of ATP depletion irrespective of whether cell Pi is lowered or raised. This suggests that raised plasma uric acid may be a marker of compromised hepatic ATP homeostasis. PMID:24045866

Petrie, John L; Patman, Gillian L; Sinha, Ishita; Alexander, Thomas D; Reeves, Helen L; Agius, Loranne

2013-11-15

152

Myofilament sliding per ATP molecule in rabbit muscle fibres studied using laser flash photolysis of caged ATP.  

PubMed

1. To estimate the distance of myofilament sliding per ATP molecule hydrolysed during the actin-myosin interaction in muscle, single glycerinated fibres prepared from rabbit psoas muscle were made to shorten under very small external loads (< or = 0.0005 maximum isometric force (Po), at 20-22 degrees C) by the laser flash photolysis of caged ATP (P3-1-(2-nitro) phenylethyladenosine 5'-triphosphate), a biologically inert and photolabile precursor of ATP. The laser flash-induced fibre shortening was recorded with a high-speed video system at 200 frames s-1. 2. Following the photochemical release of 75-300 microM ATP, the fibres shortened uniformly along the fibre length not only at the level of fibre segments but also at the level of sarcomeres. The fibres did not shorten appreciably in response to 50 microM ATP. 3. The initial velocity of the laser flash-induced fibre shortening increased with increasing concentration of released ATP, being 0.05 +/- 0.01, 0.12 +/- 0.04, 0.23 +/- 0.04, 0.38 +/- 0.03 and 0.95 +/- 0.08 microns s-1 (half-sarcomere)-1 (means +/- S.E.M., n = 10) with 75, 100, 150, 200 and 300 microM ATP, respectively. 4. The distance of the laser flash-induced fibre shortening also increased with increasing concentration of released ATP, being 10 +/- 2, 25 +/- 5, 65 +/- 7, 100 +/- 10 and 180 +/- 20 nm (half-sarcomere)-1 (means +/- S.E.M., n = 10) with 75, 100, 150, 200 and 300 microM ATP, respectively. 5. Comparison of the initial shortening velocities of the laser flash-induced shortening with the force-velocity relation of maximally Ca(2+)-activated fibres indicated the presence of considerable internal resistance against myofilament sliding following release of ATP. The initial velocity of shortening following the release of 300, 150 and 75 microM ATP was equal to the shortening velocity of maximally Ca(2+)-activated fibres under an external load of 0.55, 0.93 and 0.98 Po respectively. 6. These results suggest that, under nearly isometric conditions, the distance of myofilament sliding per ATP molecule hydrolysed is about 10 nm in each half-sarcomere. PMID:8410692

Yamada, T; Abe, O; Kobayashi, T; Sugi, H

1993-07-01

153

Aeronautics Test Program (ATP) Corporate Management of Aeronautical Facilities  

E-print Network

Aeronautics Test Program (ATP) Corporate Management of Aeronautical Facilities 44th AIAA Aerospace Activity (NATA) · Summary #12;Goals Corporate Management of Aeronautical Facilities · Increase vision and plan · NASA Aeronautics Research Mission Directorate (ARMD) commitment to sustain facilities

154

ATP-regulated K+ channels in cardiac muscle  

Microsoft Academic Search

An outward current of unknown nature increases significantly when cardiac cells are treated with cyanide or subjected to hypoxia1-4, and decreases on intracellular injection of ATP5. We report here that application of the patch-clamp technique to CN-treated mammalian heart cells reveals specific K+ channels which are depressed by intracellular ATP (ATPi) at levels greater than 1 mM. For these channels,

A. Noma

1983-01-01

155

Clinical application of adenosine and ATP for pain control  

Microsoft Academic Search

This review summarizes clinical application of adenosine and adenosine 5?-triphosphate (ATP) in pain conditions. Investigations have been performed in patients with acute perioperative pain or chronic neuropathic pain treated with intravenous adenosine or ATP, or intrathecal adenosine. Characteristic central adenosine A1 receptor-mediated pain-relieving effects have been observed after intravenous adenosine infusion in human inflammation\\/sensitization pain models and in patients with

Masakazu Hayashida; Ken-ichi Fukuda; Atsuo Fukunaga

2005-01-01

156

ATP-dependent Steps in Apoptotic Signal Transduction1  

Microsoft Academic Search

Apoptotic changes of the nucleus induced by Fas (Apo1\\/CD95) stimu- lation are completely blocked by reducing intracellular ATP level. In this study, we examined the ATP-dependent step(s) of Fas-mediated apoptotic signal transduction using two cell lines. In SKW6.4 (type I) cells charac- terized by rapid formation of the death-inducing signaling complex on Fas treatment, the activation of caspases 8, 9,

Yutaka Eguchi; Anu Srinivasan; Kevin J. Tomaselli; Shigeomi Shimizu; Yoshihide Tsujimoto

1999-01-01

157

Connexins Regulate Calcium Signaling by Controlling ATP Release  

Microsoft Academic Search

Forced expression of gap junction proteins, connexins, enables gap junction-deficient cell lines to propagate intercellular calcium waves. Here, we show that ATP secretion from the poorly coupled cell lines, C6 glioma, HeLa, and U373 glioblastoma, is potentiated 5- to 15-fold by connexin expression. ATP release required purinergic receptor-activated intracellular Ca2+ mobilization and was inhibited by Cl- channel blockers. Calcium wave

Maria Luisa Cotrina; Jane H.-C. Lin; Alexandra Alves-Rodrigues; Shujun Liu; Jiang Li; Hooman Azmi-Ghadimi; Jian Kang; Christian C. G. Naus; Maiken Nedergaard

1998-01-01

158

Glial Cell Inhibition of Neurons by Release of ATP Eric A. Newman  

E-print Network

Glial Cell Inhibition of Neurons by Release of ATP Eric A. Newman Department of Neuroscience activity by releasing ATP (Cotrina et al., 2000; Newman, 2001b). ATP, when released from neurons, functions cells have also been shown to release ATP (Cotrina et al., 1998; Wang et al., 2000; Newman, 2001b

Newman, Eric A.

159

Kinetics of PCr to ATP and ?-ATP to ?-ADP phosphoryl conversion are modified in working rat skeletal muscle after training  

Microsoft Academic Search

Kinetics of phosphoryl transfers from PCr to ?-ATP and from ?-ATP to ?-ADP were measured by magnetization transfer in an in\\u000a vivo31P NMR experiment in working rat skeletal hind leg muscles. Two groups were examined. One group was submitted to a 6-week training\\u000a program of treadmill running. The other group was composed of sedentary animals. Metabolic oxidative capacity and mechanical

Xavier Ravalec; Nathalie Le Tallec; François Carré; Jacques D. de Certaines; Elisabeth Le Rumeur

1999-01-01

160

ATP-sensitive K+ Channels in Cardiac Muscle from Cold-Acclimated Goldfish: Characterization and Altered Response to ATP  

Microsoft Academic Search

ATP-sensitive potassium channels (KATP) play an important, if incompletely defined, role in myocardial function in mammals. With the discovery that KATP channels are also present at high densities in the hearts of vertebrate ectotherms, speculation arises as to their function during periods of cold-acclimation and depressed ATP synthesis. We used single-channel and intracellular recording techniques to examine the possibility that

Rose B Ganim; Erin L Peckol; Jennie Larkin; Maureen L Ruchhoeft; John S Cameron

1998-01-01

161

Trafficking of the copper-ATPases, ATP7A and ATP7B: Role in copper homeostasis  

Microsoft Academic Search

Copper is essential for human health and copper imbalance is a key factor in the aetiology and pathology of several neurodegenerative diseases. The copper-transporting P-type ATPases, ATP7A and ATP7B are key molecules required for the regulation and maintenance of mammalian copper homeostasis. Their absence or malfunction leads to the genetically inherited disorders, Menkes and Wilson diseases, respectively. These proteins have

Sharon La Fontaine; Julian F. B. Mercer

2007-01-01

162

Extracellular ATP activates different signalling pathways in rat Sertoli cells.  

PubMed Central

1. The present study describes effects of extracellular ATP (ATPe) on plasma membrane potential and cytoplasmic Ca2+ concentrations ([Ca2+]i) in rat Sertoli cells. Sertoli cells in suspension were stimulated with ATPe and other nucleotides and ionic changes were monitored utilizing the fluorescent dyes bis-oxonol and fura-2/AM. ATPe induced a prompt plasma membrane depolarization which was dependent on Na+ influx from the extracellular medium, since it was abolished by omission of extracellular Na+. Depolarization was independent of [Ca2+]i rise as it also occurred in the absence of extracellular Ca2+ and after intracellular Ca2+ stores were discharged with thapsigargin. ATPe also stimulated a rapid and biphasic increase in [Ca2+]i: a prompt spike was followed by a prolonged sustained plateau. The initial spike was dependent on Ca2+ release from intracellular stores since it was also present when cells were incubated in EGTA-supplemented Ca(2+)-free medium and was abolished by pretreatment with ionomycin and thapsigargin, agents that discharge intracellular Ca2+ stores. The sustained phase was dependent on Ca2+ influx from the extracellular medium as it was abolished when cells were incubated in EGTA-supplemented Ca(2+)-free medium. Ca2+ influx was due to activation of voltage-operated calcium channels (VOCCs) since it was abolished by the VOCC inhibitors verapamil and nifedipine or incubation in sucrose medium, an experimental condition which precludes plasma membrane depolarization by ATPe. 2. ATPe-induced rises in intracellular Ca2+ concentration and plasma membrane depolarization were reduced by pretreatment with pertussis toxin, suggesting that ATPe-activated transduction mechanisms are in part under the control of pertussis toxin-sensitive G-proteins. These data show that Sertoli cells possess P2-purinergic receptor subtypes coupled to influx of Na+ and release of Ca2+ from intracellular stores and provide evidence for an activation of different pathways by extracellular ATPe. Activation of these receptors induces Na+ influx that causes a rapid plasma membrane depolarization. Furthermore, ATPe also triggers Ca2+ release from intracellular stores and Ca2+ influx from extracellular space via dihydropyridine-sensitive VOCCs. PMID:7575464

Foresta, C; Rossato, M; Bordon, P; Di Virgilio, F

1995-01-01

163

ATP-DEPENDENT SUGAR TRANSPORT COMPLEXITY IN HUMAN ERYTHROCYTES  

PubMed Central

Human erythrocyte glucose sugar transport was examined in resealed red cell ghosts under equilibrium exchange conditions ([sugar]intracellular = [sugar]extracellular). Exchange 3-O-methylglucose (3MG) import and export are monophasic in the absence of cytoplasmic ATP but are biphasic when ATP is present. Biphasic exchange is observed as the rapid filling of a large compartment (66% cell volume) followed by the slow filling of the remaining cytoplasmic space. Biphasic exchange at 20 mM 3MG eliminates the possibility that the rapid exchange phase represents ATP-dependent 3MG binding to the glucose transport protein (GLUT1; cellular [GLUT1] ? 20 ?M). Immunofluorescence activated cell sorting analysis shows that biphasic exchange does not result from heterogeneity in cell size or GLUT1 content. Nucleoside transporter mediated uridine exchange proceeds as rapidly as 3MG exchange but is monoexponential regardless of cytoplasmic [ATP]. This eliminates cellular heterogeneity or an ATP-dependent, nonspecific intracellular diffusion barrier as causes of biphasic exchange. Red cell ghost 3MG and uridine equilibrium volumes (130 fL) are unaffected by ATP. GLUT1 intrinsic activity is unchanged during rapid and slow phases of 3MG exchange. Two models for biphasic sugar transport are presented in which 3MG must overcome a sugar-specific, physical (diffusional) or chemical (isomerization) barrier to equilibrate with cell water. Partial transport inhibition using cytochalasin B or maltose depresses both rapid and slow phases of transport thereby eliminating the physical barrier hypothesis. We propose that biphasic 3MG transport results from ATP-dependent, differential transport of 3MG anomers in which Vmax/Km(app) for ?-3MG exchange transport is 19-fold greater than Vmax/Km(app) for ?-3MG transport. PMID:16928769

Leitch, Jeffry; Carruthers, Anthony

2014-01-01

164

Title. ATP7B copper-regulated traffic and association with the tight junctions: copper excretion into Short title. ATP7B and copper excretion by liver  

E-print Network

1 Title. ATP7B copper-regulated traffic and association with the tight junctions: copper excretion into the bile Short title. ATP7B and copper excretion by liver Authors. Sonia Hernandez*§ , Yo Tsuchiya manuscript Gastroenterology 2008;134(4):1215-23 #12;2 Abstract The copper transporter ATP7B plays a central

Boyer, Edmond

165

ATP and ADP hydrolysis in cell membranes from rat myometrium.  

PubMed

Extracellular nucleotides affect female reproductive functions, fertilization, and pregnancy. The aim of this study was to investigate biochemical characteristics of ATP and ADP hydrolysis and identify E-NTPDases in myometrial cell membranes from Wistar albino rats. The apparent K (m) values were 506.4 ± 62.1 and 638.8 ± 31.3 ?M, with a calculated V (max) (app) of 3,973.0 ± 279.5 and 2,853.9 ± 79.8 nmol/min/mg for ATP and ADP, respectively. The enzyme activity described here has common properties characteristic for NTPDases: divalent cation dependence; alkaline pH optimum for both substrates, insensitivity to some of classical ATPase inhibitors (ouabain, oligomycine, theophylline, levamisole) and significant inhibition by suramine and high concentration of sodium azides (5 mM). According to similar apparent K(m) values for both substrates, the ATP/ADP hydrolysis ratio, and Chevillard competition plot, NTPDase1 is dominant ATP/ADP hydrolyzing enzyme in myometrial cell membranes. RT-PCR analysis revealed expression of three members of ectonucleoside triphosphate diphosphohydrolase family (NTPDase 1, 2, and 8) in rat uterus. These findings may further elucidate the role of NTPDases and ATP in reproductive physiology. PMID:22956447

Miloševi?, Maja; Petrovi?, Snježana; Veli?kovi?, Nataša; Grkovi?, Ivana; Ignjatovi?, Marija; Horvat, Anica

2012-12-01

166

Phenomenological analysis of ATP dependence of motor protein  

E-print Network

In this study, through phenomenological comparison of the velocity-force data of processive motor proteins, including conventional kinesin, cytoplasmic dynein and myosin V, we found that, the ratio between motor velocities of two different ATP concentrations is almost invariant for any substall, superstall or negative external loads. Therefore, the velocity of motor can be well approximated by a Michaelis-Menten like formula $V=\\atp k(F)L/(\\atp +K_M)$, with $L$ the step size, and $k(F)$ the external load $F$ dependent rate of one mechanochemical cycle of motor motion in saturated ATP solution. The difference of Michaelis-Menten constant $K_M$ for substall, superstall and negative external load indicates, the ATP molecule affinity of motor head for these three cases are different, though the expression of $k(F)$ as a function of $F$ might be unchanged for any external load $F$. Verifications of this Michaelis-Menten like formula has also been done by fitting to the recent experimental data.

Yunxin Zhang

2011-08-09

167

ATP P2X3 receptors and neuronal sensitization  

PubMed Central

Increasing evidence indicates the importance of extracellular adenosine triphosphate (ATP) in the modulation of neuronal function. In particular, fine control of ATP release and the selective and discrete ATP receptor operation are crucial elements of the crosstalk between neuronal and non-neuronal cells in the peripheral and central nervous systems. In peripheral neurons, ATP signaling gives an important contribution to neuronal sensitization, especially that involved in neuropathic pain. Among other subtypes, P2X3 receptors expressed on sensory neurons are sensitive even to nanomolar concentrations of extracellular ATP, and therefore are important transducers of pain stimuli. P2X3 receptor function is highly sensitive to soluble factors like neuropeptides and neurotrophins, and is controlled by transduction mechanisms, protein-protein interactions and discrete membrane compartmentalization. More recent findings have demonstrated that P2X3 receptors interact with the synaptic scaffold protein calcium/calmodulin-dependent serine protein kinase (CASK) in a state dependent fashion, indicating that CASK plays a crucial role in the modulation of P2X3 receptor stability and efficiency. Activation of P2X3 receptors within CASK/P2X3 complex has important consequences for neuronal plasticity and possibly for the release of neuromodulators and neurotransmitters. Better understanding of the interactome machinery of P2X3 receptors and their integration with other receptors and channels on neuronal surface membranes, is proposed to be essential to unveil the process of neuronal sensitization and related, abnormal pain signaling. PMID:24363643

Fabbretti, Elsa

2013-01-01

168

Rotation and structure of FoF1-ATP synthase.  

PubMed

F(o)F(1)-ATP synthase is one of the most ubiquitous enzymes; it is found widely in the biological world, including the plasma membrane of bacteria, inner membrane of mitochondria and thylakoid membrane of chloroplasts. However, this enzyme has a unique mechanism of action: it is composed of two mechanical rotary motors, each driven by ATP hydrolysis or proton flux down the membrane potential of protons. The two molecular motors interconvert the chemical energy of ATP hydrolysis and proton electrochemical potential via the mechanical rotation of the rotary shaft. This unique energy transmission mechanism is not found in other biological systems. Although there are other similar man-made systems like hydroelectric generators, F(o)F(1)-ATP synthase operates on the nanometre scale and works with extremely high efficiency. Therefore, this enzyme has attracted significant attention in a wide variety of fields from bioenergetics and biophysics to chemistry, physics and nanoscience. This review summarizes the latest findings about the two motors of F(o)F(1)-ATP synthase as well as a brief historical background. PMID:21524994

Okuno, Daichi; Iino, Ryota; Noji, Hiroyuki

2011-06-01

169

Cardiac Metabolism in Heart Failure - Implications beyond ATP production  

PubMed Central

The heart has a high rate of ATP production and turnover which is required to maintain its continuous mechanical work. Perturbations in ATP generating processes may therefore affect contractile function directly. Characterizing cardiac metabolism in heart failure revealed several metabolic alterations termed metabolic remodeling, ranging from changes in substrate utilization to mitochondrial dysfunction, ultimately resulting in ATP deficiency and impaired contractility. However, ATP depletion is not the only relevant consequence of metabolic remodeling during heart failure. By providing cellular building blocks and signaling molecules, metabolic pathways control essential processes such as cell growth and regeneration. Thus, alterations in cardiac metabolism may also affect the progression to heart failure by mechanisms beyond ATP supply. Our aim is therefore to highlight that metabolic remodeling in heart failure not only results in impaired cardiac energetics, but also induces other processes implicated in the development of heart failure such as structural remodeling and oxidative stress. Accordingly, modulating cardiac metabolism in heart failure may have significant therapeutic relevance that goes beyond the energetic aspect. PMID:23989714

Doenst, Torsten; Nguyen, T. Dung; Abel, E. Dale

2013-01-01

170

ATP synthase: from single molecule to human bioenergetics  

PubMed Central

ATP synthase (FoF1) consists of an ATP-driven motor (F1) and a H+-driven motor (Fo), which rotate in opposite directions. FoF1 reconstituted into a lipid membrane is capable of ATP synthesis driven by H+ flux. As the basic structures of F1 (?3?3???) and Fo (ab2c10) are ubiquitous, stable thermophilic FoF1 (TFoF1) has been used to elucidate molecular mechanisms, while human F1Fo (HF1Fo) has been used to study biomedical significance. Among F1s, only thermophilic F1 (TF1) can be analyzed simultaneously by reconstitution, crystallography, mutagenesis and nanotechnology for torque-driven ATP synthesis using elastic coupling mechanisms. In contrast to the single operon of TFoF1, HFoF1 is encoded by both nuclear DNA with introns and mitochondrial DNA. The regulatory mechanism, tissue specificity and physiopathology of HFoF1 were elucidated by proteomics, RNA interference, cytoplasts and transgenic mice. The ATP synthesized daily by HFoF1 is in the order of tens of kilograms, and is primarily controlled by the brain in response to fluctuations in activity. PMID:20689227

KAGAWA, Yasuo

2010-01-01

171

Calcium regulation of tension redevelopment kinetics with 2-deoxy-ATP or low [ATP] in rabbit skeletal muscle.  

PubMed Central

The correlation of acto-myosin ATPase rate with tension redevelopment kinetics (k(tr)) was determined during Ca(+2)-activated contractions of demembranated rabbit psoas muscle fibers; the ATPase rate was either increased or decreased relative to control by substitution of ATP (5.0 mM) with 2-deoxy-ATP (dATP) (5.0 mM) or by lowering [ATP] to 0.5 mM, respectively. The activation dependence of k(tr) and unloaded shortening velocity (Vu) was measured with each substrate. With 5.0 mM ATP, Vu depended linearly on tension (P), whereas k(tr) exhibited a nonlinear dependence on P, being relatively independent of P at submaximum levels and rising steeply at P > 0.6-0.7 of maximum tension (Po). With dATP, Vu was 25% greater than control at Po and was elevated at all P > 0.15Po, whereas Po was unchanged. Furthermore, the Ca(+2) sensitivity of both k(tr) and P increased, such that the dependence of k(tr) on P was not significantly different from control, despite an elevation of Vu and maximal k(tr). In contrast, lowering [ATP] caused a slight (8%) elevation of Po, no change in the Ca(+2) sensitivity of P, and a decrease in Vu at all P. Moreover, k(tr) was decreased relative to control at P > 0.75Po, but was elevated at P < 0.75Po. These data demonstrate that the cross-bridge cycling rate dominates k(tr) at maximum but not submaximum levels of Ca(2+) activation. PMID:9545059

Regnier, M; Martyn, D A; Chase, P B

1998-01-01

172

Heat shock protein 70 (Hsp70) inhibits oxidative phosphorylation and compensates ATP balance through enhanced glycolytic activity  

PubMed Central

To address possible effects of heat shock protein 70 (Hsp70) on energy metabolism, we established a cell line expressing different levels of Hsp70 and evaluated changes in glucose and lactate metabolites, as well as ATP levels accordingly. In addition, activities of enzymes involved in glycolysis [phosphofructokinase (PFK) and lactate dehydrogenase (LDH)], Krebs cycle [citric synthase (CS)], and oxidative phosphorylation {NADH dehydrogenase [complex I (CI)] and ubiquinol:cytochrome-c reductase [complex III (CIII)]} were analyzed. The results show that both glucose consumption and lactate excretion were elevated significantly in cells expressing increased levels of Hsp70. Simultaneously, the activities of glycolytic enzymes PFK and LDH were increased markedly in cells overexpressing Hsp70. Activities of enzymes CI and CIII, both involved in oxidative phosphorylation, decreased upon increased expression of Hsp70. These findings were supported by nonsignificant reductions of CS activities in cells that overexpressed Hsp70, whereas intracellular ATP levels remained constant over a wide range of Hsp70 expression. In conclusion, overexpression of Hsp70 in HeLa cells results in downregulation of oxidative phosphorylation, in particular, multiprotein CIII, the main source of reactive oxygen species. In exchange, upregulation of the glycolytic pathway compensates for the homeostasis of cellular ATP supply. PMID:23042904

Wang, Liangli; Schumann, Uwe; Prokopchuk, Olga; Steinacker, Jürgen M.

2012-01-01

173

ATP and AMP Mutually Influence Their Interaction with the ATP-binding Cassette (ABC) Adenylate Kinase Cystic Fibrosis Transmembrane Conductance Regulator (CFTR) at Separate Binding Sites*  

PubMed Central

Cystic fibrosis transmembrane conductance regulator (CFTR) is an anion channel in the ATP-binding cassette (ABC) transporter protein family. In the presence of ATP and physiologically relevant concentrations of AMP, CFTR exhibits adenylate kinase activity (ATP + AMP ? 2 ADP). Previous studies suggested that the interaction of nucleotide triphosphate with CFTR at ATP-binding site 2 is required for this activity. Two other ABC proteins, Rad50 and a structural maintenance of chromosome protein, also have adenylate kinase activity. All three ABC adenylate kinases bind and hydrolyze ATP in the absence of other nucleotides. However, little is known about how an ABC adenylate kinase interacts with ATP and AMP when both are present. Based on data from non-ABC adenylate kinases, we hypothesized that ATP and AMP mutually influence their interaction with CFTR at separate binding sites. We further hypothesized that only one of the two CFTR ATP-binding sites is involved in the adenylate kinase reaction. We found that 8-azidoadenosine 5?-triphosphate (8-N3-ATP) and 8-azidoadenosine 5?-monophosphate (8-N3-AMP) photolabeled separate sites in CFTR. Labeling of the AMP-binding site with 8-N3-AMP required the presence of ATP. Conversely, AMP enhanced photolabeling with 8-N3-ATP at ATP-binding site 2. The adenylate kinase active center probe P1,P5-di(adenosine-5?) pentaphosphate interacted simultaneously with an AMP-binding site and ATP-binding site 2. These results show that ATP and AMP interact with separate binding sites but mutually influence their interaction with the ABC adenylate kinase CFTR. They further indicate that the active center of the adenylate kinase comprises ATP-binding site 2. PMID:23921386

Randak, Christoph O.; Dong, Qian; Ver Heul, Amanda R.; Elcock, Adrian H.; Welsh, Michael J.

2013-01-01

174

Kinetics of ATP and TNP-ATP binding to the active site of CheA from Thermotoga maritima.  

PubMed

The mechanism of nucleotide binding to the active site of Thermotoga maritima CheA was investigated using stopped-flow fluorescence experiments that monitored binding of ATP and TNP-ATP to the catalytic domain (P4) of CheA that had been engineered to include a tryptophan residue as a fluorescent reporter group at the active site (P4(F487W)). Rapid decreases in protein intrinsic fluorescence and increases in TNP-ATP fluorescence were observed during binding reactions, and time courses were analyzed to define the kinetic mechanisms for ATP and TNP-ATP binding. This analysis indicated that binding of ATP(Mg(2+)) to P4(F487W) involves a single reversible step with a k(on) of 0.92 +/- 0.09 microM(-1) s(-1), a k(off) of 1.9 +/- 0.4 s(-1), and a K(d) of 1.5-2.1 microM (all values determined at 4 degrees C). Binding of TNP-ATP(Mg(2+)) to P4(F487W) involves a more complicated mechanism, requiring at least three sequential steps. Computer simulations and nonlinear regression analysis were used to estimate the rate constants of the forward and reverse reactions for each of the three steps in the reaction scheme [Formula: see text] Similar analysis indicated that an alternative reaction scheme, involving a rate-limiting conformational change in P4 prior to TNP-ATP binding, did an equally good job of accounting for all of the kinetics results:[Formula: see text] In both models, steps 2 and 3 have slow reversal rates that contribute to the high affinity of the active site for TNP-ATP (K(d) = 0.015 microM). These results highlight the dramatic effect of the TNP moieties on CheA-nucleotide interactions, and they provide the first detailed information about the kinetic mechanism underlying interaction of a protein histidine kinase with this tight-binding inhibitor. PMID:20565117

Eaton, Anna K; Stewart, Richard C

2010-07-13

175

Release of Adenosine and ATP During Ischemia and Epilepsy  

PubMed Central

Eighty years ago Drury & Szent-Györgyi described the actions of adenosine, AMP (adenylic acid) and ATP (pyrophosphoric or diphosphoric ester of adenylic acid) on the mammalian cardiovascular system, skeletal muscle, intestinal and urinary systems. Since then considerable insight has been gleaned on the means by which these compounds act, not least of which in the distinction between the two broad classes of their respective receptors, with their many subtypes, and the ensuing diversity in cellular consequences their activation invokes. These myriad actions are of course predicated on the release of the purines into the extracellular milieu, but, surprisingly, there is still considerable ambiguity as to how this occurs in various physiological and pathophysiological conditions. In this review we summarise the release of ATP and adenosine during seizures and cerebral ischemia and discuss mechanisms by which the purines adenosine and ATP may be released from cells in the CNS under these conditions. PMID:20190959

Dale, Nicholas; Frenguelli, Bruno G

2009-01-01

176

ATP Exhibits Antimicrobial Action by Inhibiting Bacterial Utilization of Ferric Ions  

PubMed Central

ATP up-regulates macrophage antimycobacterial activity in a P2X7-dependent manner, but little is known about whether ATP directly exhibits antimicrobial effects against intracellular mycobacteria. In this study, we found that ATP inhibited the growth of various bacteria, including Staphylococcus, Pseudomonas, and mycobacteria, without damaging bacterial surface structures. Using gene technology, we newly established an enterobactin-deficient (entB?) mutant from ATP-resistant Klebsiella pneumoniae, and found the recovery of ATP susceptibility in the enterobactin-deleted mutant. Therefore, ATP's antibacterial activity is attributable to its iron-chelating ability. Since ATP distributed in the cytosol of macrophages at high concentrations, ATP appears to augment macrophage's antimicrobial activity by directly attacking intracytosolic and intra-autophagosomal pathogens. Furthermore, ATP exhibited combined effects with some antimicrobials against methicillin-resistant S. aureus (MRSA) and M. intracellulare, suggesting its usefulness as an adjunctive drug in the chemotherapy of certain intractable infections. PMID:25712807

Tatano, Yutaka; Kanehiro, Yuichi; Sano, Chiaki; Shimizu, Toshiaki; Tomioka, Haruaki

2015-01-01

177

Cloning, expression and bioinformatics analysis of ATP sulfurylase from Acidithiobacillus ferrooxidans ATCC 23270 in Escherichia coli  

PubMed Central

Molecular studies of enzymes involved in sulfite oxidation in Acidithiobacillus ferrooxidans have not yet been developed, especially in the ATP sulfurylase (ATPS) of these acidophilus tiobacilli that have importance in biomining. This enzyme synthesizes ATP and sulfate from adenosine phosphosulfate (APS) and pyrophosphate (PPi), final stage of the sulfite oxidation by these organisms in order to obtain energy. The atpS gene (1674 bp) encoding the ATPS from Acidithiobacillus ferrooxidans ATCC 23270 was amplified using PCR, cloned in the pET101-TOPO plasmid, sequenced and expressed in Escherichia coli obtaining a 63.5 kDa ATPS recombinant protein according to SDS-PAGE analysis. The bioinformatics and phylogenetic analyses determined that the ATPS from A. ferrooxidans presents ATP sulfurylase (ATS) and APS kinase (ASK) domains similar to ATPS of Aquifex aeolicus, probably of a more ancestral origin. Enzyme activity towards ATP formation was determined by quantification of ATP formed from E. coli cell extracts, using a bioluminescence assay based on light emission by the luciferase enzyme. Our results demonstrate that the recombinant ATP sulfurylase from A. ferrooxidans presents an enzymatic activity for the formation of ATP and sulfate, and possibly is a bifunctional enzyme due to its high homology to the ASK domain from A. aeolicus and true kinases. PMID:23055613

Jaramillo, Michael L; Abanto, Michel; Quispe, Ruth L; Calderón, Julio; del Valle, Luís J; Talledo, Miguel; Ramírez, Pablo

2012-01-01

178

Characterization of Na+ influx mediated by ATP(4-)-activated P2 purinoceptors in PC12 cells.  

PubMed Central

1. Micromolar levels of extracellular ATP increased cytosolic Na+ concentration ([Na+]i) as well as cytosolic Ca2+ concentration ([Ca2+]i) in PC12 cells. 2. Pretreatment of cells with tetrodotoxin, benzamil or thapsigargin did not alter the ATP-induced Na+ influx. 3. Increased extracellular Mg2+ concentration decreased the ATP effect. Furthermore, when the extracellular ATP pool was treated to contain corresponding calculated concentrations of ATP4-, the increase in [Na+]i stayed linked to the ATP4- concentration rather than to the total ATP concentrations in the stimulants. 4. Extracellular ATP does not create nonselective pores as shown by the fact that ethidium bromide does not enter the cells upon ATP stimulation. 5. Among the tested nucleotides, only adenosine 5'-O-(3-thiotriphosphate), 2-methylthio ATP and 2-chloro ATP also caused Na+ influx. 6. Reactive Blue 2 specifically decreased the ATP effect in a concentration-dependent manner. 7. The results suggest that extracellular ATP triggers Na+ influx through a P2 purinoceptor which is activated by ATP4- in PC12 cells. Images Figure 4 PMID:8799565

Choi, S. Y.; Kim, K. T.

1996-01-01

179

Paracrine stimulation of P2X7 receptor by ATP activates a proliferative pathway in ovarian carcinoma cells.  

PubMed

P2X7 is a purinergic receptor-channel; its activation by ATP elicits a broad set of cellular actions, from apoptosis to signals for survival. Here, P2X7 expression and function was studied in human ovarian carcinoma (OCA) cells, and biopsies from non-cancerous and cancer patients were analyzed by immunohistochemistry. Ovarian surface epithelium in healthy tissue expressed P2X7 at a high level that was maintained throughout the cancer. The cell lines SKOV-3 and CAOV-3 were used to investigate P2X7 functions in OCA. In SKOV-3 cells, selective stimulation of P2X7 by 2'(3')-O-(4-benzoylbenzoyl) adenosine-5'-triphosphate (BzATP) induced a dose-dependent increase of intracellular Ca(2+) concentration ([Ca(2+)](i)) but not cell death. Instead, BzATP increased the levels of phosphorylated ERK and AKT (pERK and pAKT), with an EC(50) of 44?±?2 and 1.27?±?0.5??M, respectively; 10??M BzATP evoked a maximum effect within 15?min that lasted for 120?min. Interestingly, basal levels of pERK and pAKT were decreased in the presence of apyrase in the medium, strongly suggesting an endogenous, ATP-mediated phenomenon. Accordingly: (i) mechanically stimulated cells generated a [Ca(2+)](i) increase that was abolished by apyrase; (ii) apyrase induced a decrease in culture viability, as measured by the MTS assay for mitochondrial activity; and (iii) incubation with 10??M AZ10606120, a specific P2X7 antagonist and transfection with the dominant negative P2X7 mutant E496A, both reduced cell viability to 70.1?±?8.9% and to 76.5?±?5%, respectively, of control cultures. These observations suggested that P2X7 activity was auto-induced through ATP efflux; this increased pERK and pAKT levels that generated a positive feedback on cell viability. PMID:24913779

Vázquez-Cuevas, Francisco G; Martínez-Ramírez, Angélica S; Robles-Martínez, Leticia; Garay, Edith; García-Carrancá, Alejandro; Pérez-Montiel, Delia; Castañeda-García, Carolina; Arellano, Rogelio O

2014-11-01

180

NIF Title III engineering plan  

SciTech Connect

The purpose of this document is to define the work that must be accomplished by the NIF Project during Title III Engineering. This definition is intended to be sufficiently detailed to provide a framework for yearly planning, to clearly identify the specific deliverables so that the Project teams can focus on them, and to provide a common set of objectives and processes across the Project. This plan has been preceded by similar documents for Title I and Title II design and complements the Site Management Plan, the Project Control Manual, the Quality Assurance Program Plan, the RM Parsons NIF Title III Configuration Control Plan, the Integrated Project Schedule, the Preliminary Safety Analysis Report, the Configuration Management Plan, and the Transition Plan.

Deis, G

1998-06-01

181

ATP-Sensitive K+ Channels: Paradigm Lost, Paradigm Regained  

NSDL National Science Digital Library

Access to the article is free, however registration and sign-in are required. In an update of a previous Perspective [L. H. Philipson and D. F. Steiner, Science 268, 372 (1995)], Philipson discusses the molecular basis for Ksubscript ATP, a potassium current that mediates glucose regulation of insulin secretion. A prediction in the previous Perspective is borne out by a paper in this issue of Science (Inagaki et al., p. 1166), which reports the cloning of a new inward rectifier potassium channel and shows that Ksubscript ATP is formed when this channel combines with the sulfonylurea receptor.

Louis H. Philipson (University of Chicago; Department of Medicine and is on the Committee on Cell Physiology)

1995-11-17

182

Slipping up: partial substrate degradation by ATP-dependent proteases.  

PubMed

ATP-dependent proteases are present in all organisms, where they are responsible for much of intracellular protein degradation. Most proteins are processively unfolded and degraded into small peptides; however, in a few so-called slippery substrates, the protease stalls at a folded domain and releases a large protein fragment. In this review, we describe the properties of physiological slippery substrates that are processed in this manner by ATP-dependent proteases and the recent advances that have been made in understanding the mechanism underlying their partial degradation. PMID:24823973

Nassif, Nicholas D; Cambray, Samantha E; Kraut, Daniel A

2014-05-01

183

Processing mechanics of alternate twist ply (ATP) yarn technology  

NASA Astrophysics Data System (ADS)

Ply yarns are important in many textile manufacturing processes and various applications. The primary process used for producing ply yarns is cabling. The speed of cabling is limited to about 35m/min. With the world's increasing demands of ply yarn supply, cabling is incompatible with today's demand activated manufacturing strategies. The Alternate Twist Ply (ATP) yarn technology is a relatively new process for producing ply yarns with improved productivity and flexibility. This technology involves self plying of twisted singles yarn to produce ply yarn. The ATP process can run more than ten times faster than cabling. To implement the ATP process to produce ply yarns there are major quality issues; uniform Twist Profile and yarn Twist Efficiency. The goal of this thesis is to improve these issues through process modeling based on understanding the physics and processing mechanics of the ATP yarn system. In our study we determine the main parameters that control the yarn twist profile. Process modeling of the yarn twist across different process zones was done. A computational model was designed to predict the process parameters required to achieve a square wave twist profile. Twist efficiency, a measure of yarn torsional stability and bulk, is determined by the ratio of ply yarn twist to singles yarn twist. Response Surface Methodology was used to develop the processing window that can reproduce ATP yarns with high twist efficiency. Equilibrium conditions of tensions and torques acting on the yarns at the self ply point were analyzed and determined the pathway for achieving higher twist efficiency. Mechanistic modeling relating equilibrium conditions to the twist efficiency was developed. A static tester was designed to zoom into the self ply zone of the ATP yarn. A computer controlled, prototypic ATP machine was constructed and confirmed the mechanistic model results. Optimum parameters achieving maximum twist efficiency were determined in this study. The successful results of this work have led to the filing of a US patent disclosing the method for producing ATP yarns with high yarn twist efficiency using a high convergence angle at the self ply point together with applying ply torque.

Elkhamy, Donia Said

184

Functional studies of ATP sulfurylase from Penicillium chrysogenum  

SciTech Connect

ATP sulfurylase from Penicillium chrysogenum has a specific activity (V/sub max/) of 6-7 units x mg protein/sup -1/ determined with the physiological substrates of MgATP and SO/sub 4//sup 2 -/ and assayed by (A) initial velocity measurements with APS kinase and inorganic pyrophosphatase present and (B) analysis of nonlinear reaction progress curves. The fact both assays give the same results show the intrinsic activity of ATP sulfurylase is much higher than previously reported. In initial velocity dead-end inhibition studies, the sulfate analog S/sub 2/O/sub 3//sup 2 -/ is a competitive inhibitor of SO/sub 42/..sqrt.. and a noncompetitive inhibitor of MgATP. Monovalent oxyanions such as NO/sub 3//sup -/, ClO/sub 3//sup -/, ClO/sub 4//sup -/, and FSO/sub 3//sup -/ behave as uncompetitive inhibitors of MgATP and thus seem not to be true sulfate analogs. The reverse reaction was assayed by the pyrophosphate dependent release of /sup 35/SO/sub 4//sup 2 -/ from AP/sup 35/S. Product inhibition by MgATP or SO/sub 4//sup 2 -/ is competitive with APS and mixed-type with PP/sub i/. Imidodiphosphate can serve as an alternative substrate for PP/sub i/. ATP sulfurylase binds (but does not hydrolyze) APS. A Scatchard plot of the APS binding is nonlinear, suggesting at least two types of sites. The cumulative results are qualitatively consistent with the random addition of MgATP and SO/sub 4//sup 2 -/ and the ordered release of first MgPP/sub i/ then APS, with APS release being partially rate limiting. Certain quantitative discrepancies suggest either an unknown variable (e.g. enzyme concentration) complicates the analysis or, in light of binding studies that the actual mechanism is more complicated (e.g. alternating sites) than any of the conventional models examined.

Seubert, P.A.

1985-01-01

185

Extracellular ATP in the Immune System: More Than Just a "Danger Signal"  

NSDL National Science Digital Library

Extracellular adenosine 5?-triphosphate (eATP) is ubiquitously used for cell-to-cell communication. The low concentration of eATP ([eATP]) that exists in a “halo” surrounding resting cells signals the presence of neighboring living cells. Transient increases in [eATP] are used for basic physiological signaling, namely, in the nervous and vascular systems. Larger increases in [eATP] that are associated with cell death serve as a key “danger” signal in inflammatory processes. Two studies now point to roles for ATP in the immune system: providing a costimulatory signal to T cells and driving the differentiation of intestinal T helper 17 (TH17) cells.

Alain Trautmann (France; Universit預aris Descartes REV)

2009-02-03

186

Association of 20 potential ATP2B1-interacting genes with blood pressure in Koreans  

Microsoft Academic Search

Plasma membrane calcium-transporting ATPase 1 (ATP2B1) is associated significantly with blood pressure in Caucasians and Asians. ATP2B1 regulates calcium homeostasis and belongs\\u000a to the P-type calcium pump family; several studies have identified diverse proteins that bind to ATP2B1. We hypothesized that\\u000a ATP2B1 regulates blood pressure through ATP2B1-interacting genes. To this end, 20 potential ATP2B1-interacting genes were\\u000a selected, 197 SNPs of

Kyung-Won Hong; Hyun-Seok Jin; Ji-Eun Lim; Bermseok Oh

2011-01-01

187

Characterization of ATP Alternations in an Alzheimer’s Transgenic Mouse Model  

PubMed Central

Mitochondrial impairment as evidenced by decline in adenosine 5?-triphosphate (ATP) is associated with oxidative stress in Alzheimer’s neuropathology and suggests that mitochondria may fail to maintain cellular energy, through reduced ATP production in neurons. To gain insights into the ATP characteristics of Alzheimer’s disease transgenic (Tg) mice, we investigated ATP contents in the brain and whole blood of Tg mice at three ages (1-, 5- and 24-month-old). Overall, our results demonstrate that tissue ATP contents in Tg mice are significantly reduced, suggesting a decrease of tissue ATP production and mitochondrial dysfunction. PMID:25261448

Zhang, Cheng; Rissman, Robert A.; Feng, June

2014-01-01

188

APPENDIX III III.1 Precipitation Daily Totals Preceding Precipitation Events-----------------------------------------III-2  

E-print Network

----------------------------------------------------------------------------III-10 III.3.3 Sediment discharge file: run4.q-------------------------------------------------------------------------- III-6 III.3.2 Discharge file: run4.q ----------------------------------------------------------------III-10 III.4 Event 2 Hydrographs and Sediment Graphs

Julien, Pierre Y.

189

Natural variation in the ATPS1 isoform of ATP sulfurylase contributes to the control of sulfate levels in Arabidopsis.  

PubMed

Sulfur is an essential macronutrient for all living organisms. Plants take up inorganic sulfate from the soil, reduce it, and assimilate it into bioorganic compounds, but part of this sulfate is stored in the vacuoles. In our first attempt to identify genes involved in the control of sulfate content in the leaves, we reported that a quantitative trait locus (QTL) for sulfate content in Arabidopsis (Arabidopsis thaliana) was underlain by the APR2 isoform of the key enzyme of sulfate assimilation, adenosine 5'-phosphosulfate reductase. To increase the knowledge of the control of this trait, we cloned a second QTL from the same analysis. Surprisingly, the gene underlying this QTL encodes the ATPS1 isoform of the enzyme ATP sulfurylase, which precedes adenosine 5'-phosphosulfate reductase in the sulfate assimilation pathway. Plants with the Bay allele of ATPS1 accumulate lower steady-state levels of ATPS1 transcript than those with the Sha allele, which leads to lower enzyme activity and, ultimately, the accumulation of sulfate. Our results show that the transcript variation is controlled in cis. Examination of ATPS1 sequences of Bay-0 and Shahdara identified two deletions in the first intron and immediately downstream the gene in Bay-0 shared with multiple other Arabidopsis accessions. The average ATPS1 transcript levels are lower in these accessions than in those without the deletions, while sulfate levels are significantly higher. Thus, sulfate content in Arabidopsis is controlled by two genes encoding subsequent enzymes in the sulfate assimilation pathway but using different mechanisms, variation in amino acid sequence and variation in expression levels. PMID:24027241

Koprivova, Anna; Giovannetti, Marco; Baraniecka, Patrycja; Lee, Bok-Rye; Grondin, Cécile; Loudet, Olivier; Kopriva, Stanislav

2013-11-01

190

Volume-dependent ATP-conductive large-conductance anion channel as a pathway for swelling-induced ATP release.  

PubMed

In mouse mammary C127i cells, during whole-cell clamp, osmotic cell swelling activated an anion channel current, when the phloretin-sensitive, volume-activated outwardly rectifying Cl(-) channel was eliminated. This current exhibited time-dependent inactivation at positive and negative voltages greater than around +/-25 mV. The whole-cell current was selective for anions and sensitive to Gd(3)+. In on-cell patches, single-channel events appeared with a lag period of approximately 15 min after a hypotonic challenge. Under isotonic conditions, cell-attached patches were silent, but patch excision led to activation of currents that consisted of multiple large-conductance unitary steps. The current displayed voltage- and time-dependent inactivation similar to that of whole-cell current. Voltage-dependent activation profile was bell-shaped with the maximum open probability at -20 to 0 mV. The channel in inside-out patches had the unitary conductance of approximately 400 pS, a linear current-voltage relationship, and anion selectivity. The outward (but not inward) single-channel conductance was suppressed by extracellular ATP with an IC(50) of 12.3 mM and an electric distance (delta) of 0.47, whereas the inward (but not outward) conductance was inhibited by intracellular ATP with an IC(50) of 12.9 mM and delta of 0.40. Despite the open channel block by ATP, the channel was ATP-conductive with P(ATP)/P(Cl) of 0.09. The single-channel activity was sensitive to Gd(3)+, SITS, and NPPB, but insensitive to phloretin, niflumic acid, and glibenclamide. The same pharmacological pattern was found in swelling-induced ATP release. Thus, it is concluded that the volume- and voltage-dependent ATP-conductive large-conductance anion channel serves as a conductive pathway for the swelling-induced ATP release in C127i cells. PMID:11524456

Sabirov, R Z; Dutta, A K; Okada, Y

2001-09-01

191

Extracellular ATP inhibits root gravitropism at concentrations that inhibit polar auxin transport  

NASA Technical Reports Server (NTRS)

Raising the level of extracellular ATP to mM concentrations similar to those found inside cells can block gravitropism of Arabidopsis roots. When plants are grown in Murashige and Skoog medium supplied with 1 mM ATP, their roots grow horizontally instead of growing straight down. Medium with 2 mM ATP induces root curling, and 3 mM ATP stimulates lateral root growth. When plants are transferred to medium containing exogenous ATP, the gravity response is reduced or in some cases completely blocked by ATP. Equivalent concentrations of ADP or inorganic phosphate have slight but usually statistically insignificant effects, suggesting the specificity of ATP in these responses. The ATP effects may be attributable to the disturbance of auxin distribution in roots by exogenously applied ATP, because extracellular ATP can alter the pattern of auxin-induced gene expression in DR5-beta-glucuronidase transgenic plants and increase the response sensitivity of plant roots to exogenously added auxin. The presence of extracellular ATP also decreases basipetal auxin transport in a dose-dependent fashion in both maize (Zea mays) and Arabidopsis roots and increases the retention of [(3)H]indole-3-acetic acid in root tips of maize. Taken together, these results suggest that the inhibitory effects of extracellular ATP on auxin distribution may happen at the level of auxin export. The potential role of the trans-plasma membrane ATP gradient in auxin export and plant root gravitropism is discussed.

Tang, Wenqiang; Brady, Shari R.; Sun, Yu; Muday, Gloria K.; Roux, Stanley J.

2003-01-01

192

Structural Basis for Substrate Binding and the Catalytic Mechanism of Type III Pantothenate Kinase  

SciTech Connect

Pantothenate kinase (PanK) catalyzes the first step of the universal five-step coenzyme A (CoA) biosynthetic pathway. The recently characterized type III PanK (PanK-III, encoded by the coaX gene) is distinct in sequence, structure and enzymatic properties from both the long-known bacterial type I PanK (PanK-I, exemplified by the Escherichia coli CoaA protein) and the predominantly eukaryotic type II PanK (PanK-II). PanK-III enzymes have an unusually high K{sub m} for ATP, are resistant to feedback inhibition by CoA, and are unable to utilize the N-alkylpantothenamide family of pantothenate analogues as alternative substrates, thus making type III PanK ineffective in generating CoA analogues as antimetabolites in vivo. Previously, we reported the crystal structure of the PanK-III from Thermotoga maritima and identified it as a member of the 'acetate and sugar kinase/heat shock protein 70/actin' (ASKHA) superfamily. Here we report the crystal structures of the same PanK-III in complex with one of its substrates (pantothenate), its product (phosphopantothenate) as well as a ternary complex structure of PanK-III with pantothenate and ADP. These results are combined with isothermal titration calorimetry experiments to present a detailed structural and thermodynamic characterization of the interactions between PanK-III and its substrates ATP and pantothenate. Comparison of substrate binding and catalytic sites of PanK-III with that of eukaryotic PanK-II revealed drastic differences in the binding modes for both ATP and pantothenate substrates, and suggests that these differences may be exploited in the development of new inhibitors specifically targeting PanK-III.

Yang, Kun; Strauss, Erick; Huerta, Carlos; Zhang, Hong (Stellenbosch); (UTSMC)

2008-07-15

193

RESEARCH PAPER Role of ATP and related purines in inhibitory  

E-print Network

of Veterinary Basic Sciences, Royal Veterinary College, London, UK Background and purpose: As adenosine 5, produced frequency- and concentration-dependent relaxations respectively. Adenosine 5-diphosphate (ADP) and adenosine were more potent than ATP in producing relaxation, while uridine 5-triphosphate, uridine 5

Burnstock, Geoffrey

194

Intertwined translational regulations set uneven stoichiometry of chloroplast ATP synthase  

E-print Network

of several organelle-encoded subunits is regulated at the translational step in an assembly-dependent mannerIntertwined translational regulations set uneven stoichiometry of chloroplast ATP synthase subunits mechanism ensur- ing this unique stoichiometry, required for the functional assembly of the chloroplast

195

ATP Released from Astrocytes Mediates Glial Calcium Waves  

Microsoft Academic Search

Calcium waves represent a widespread form of intercellular communication. Although they have been thought for a long time to require gap junctions, we recently demonstrated that mouse cortical astrocytes use an extracellular messenger for calcium wave propagation. The present experiments identify ATP as a major extracellular messenger in this system. Medium collected from astrocyte cultures during (but not before) cal-

Peter B. Guthrie; Joshua Knappenberger; Menahem Segal; Michael V. L. Bennett; Andrew C. Charles; S. B. Kater

196

ATP 3-20.16 Mobile Gun System Platoon  

E-print Network

ATP 3-20.16 Mobile Gun System Platoon February 2013 Headquarters, Department of the Army of the Army Washington, DC, 15 February 2013 Mobile Gun System Platoon Contents Page PREFACE OF THE MOBILE GUN SYSTEM PLATOON ...2-1 Section I ­ Text References.......................................2

US Army Corps of Engineers

197

IV ATP potentiates midazolam sedation as assessed by bispectral index.  

PubMed

In this study, by measuring bispectral index (BIS), we tested the hypothesis that intravenous adenosine 5'-triphosphate (ATP) infusion would deepen the level of midazolam-induced sedation. Ten healthy volunteers underwent 2 experiments with at least 2 weeks' interval: immediately after intravenous bolus administration of midazolam (0.04 mg/kg), they received continuous infusion of either ATP infusion (100 ?g/kg/min) or placebo (saline) for 40 minutes in a double-blind, randomized, crossover manner. Changes in BIS values and responsiveness to verbal command as well as cardiorespiratory variables were observed throughout the study periods. Administration of midazolam alone reduced BIS value from control: 97 ± 1 to 68 ± 18 at 25 minutes, which was accompanied by significant cardiopulmonary depressant effects, while maintaining responsiveness to verbal command (consciousness) throughout the study period. Coadministration of ATP with midazolam further reduced BIS value to 51 ± 13, associated with complete loss of consciousness without adverse effect on the cardiorespiratory systems. We conclude that the addition of ATP infusion to midazolam significantly enhances midazolam sedation without disturbing cardiorespiratory functions. PMID:25191981

Sakurai, Satoru; Fukunaga, Atsuo; Ichinohe, Tatsuya; Kaneko, Yuzuru

2014-01-01

198

Detection of ATP and NADH: A Bioluminescent Experience.  

ERIC Educational Resources Information Center

Described is a bioluminescent assay for adenosine triphosphate (ATP) and reduced nicotineamide-adenine dinucleotide (NADH) that meets the requirements of an undergraduate biochemistry laboratory course. The 3-hour experiment provides students with experience in bioluminescence and analytical biochemistry yet requires limited instrumentation,…

Selig, Ted C.; And Others

1984-01-01

199

ATP Synthase Inhibition of Mycobacterium avium Is Not Bactericidal?  

PubMed Central

The efficacy of ATP synthase inhibitor TMC207 was assessed in early and late Mycobacterium avium infections in mice. In contrast to what was earlier observed for M. tuberculosis, a bacteriostatic effect was obtained. In vitro, the minimal bactericidal concentration (MBC)/MIC ratio was very high. The MBC was more relevant for assessment of pharmacokinetic/pharmacodynamic relationships than the MIC. PMID:19738016

Lounis, Nacer; Gevers, Tom; Van Den Berg, Joke; Vranckx, Luc; Andries, Koen

2009-01-01

200

ATP Binding Turns Plant Cryptochrome Into an Efficient Natural Photoswitch  

NASA Astrophysics Data System (ADS)

Cryptochromes are flavoproteins that drive diverse developmental light-responses in plants and participate in the circadian clock in animals. Plant cryptochromes have found application as photoswitches in optogenetics. We have studied effects of pH and ATP on the functionally relevant photoreduction of the oxidized FAD cofactor to the semi-reduced FADH. radical in isolated Arabidopsis cryptochrome 1 by transient absorption spectroscopy on nanosecond to millisecond timescales. In the absence of ATP, the yield of light-induced radicals strongly decreased with increasing pH from 6.5 to 8.5. With ATP present, these yields were significantly higher and virtually pH-independent up to pH 9. Analysis of our data in light of the crystallographic structure suggests that ATP-binding shifts the pKa of aspartic acid D396, the putative proton donor to FAD.-, from ~7.4 to >9, and favours a reaction pathway yielding long-lived aspartate D396-. Its negative charge could trigger conformational changes necessary for signal transduction.

Müller, Pavel; Bouly, Jean-Pierre; Hitomi, Kenichi; Balland, Véronique; Getzoff, Elizabeth D.; Ritz, Thorsten; Brettel, Klaus

2014-06-01

201

Abiogenic Photophosphorylation of ADP to ATP Sensitized by Flavoproteinoid Microspheres  

NASA Astrophysics Data System (ADS)

A model for abiogenic photophosphorylation of ADP by orthophosphate to yield ATP was studied. The model is based on the photochemical activity of flavoproteinoid microspheres that are formed by aggregation in an aqueous medium of products of thermal condensation of a glutamic acid, glycine and lysine mixture (8:3:1) and contain, along with amino acid polymers (proteinoids), abiogenic isoalloxazine (flavin) pigments. Irradiation of aqueous suspensions of microspheres with blue visible light or ultraviolet in the presence of ADP and orthophosphate resulted in ATP formation. The yield of ATP in aerated suspensions was 10 20% per one mol of starting ADP. Deaeration reduced the photophosphorylating activity of microspheres five to 10 times. Treatment of aerated microsphere suspensions with superoxide dismutase during irradiation partially suppressed ATP formation. Deaerated microspheres restored completely their photophosphorylating activity after addition of hydrogen peroxide to the suspension. The photophosphorylating activity of deaerated suspensions of flavoproteinoid microspheres was also recovered by introduction of Fe3+-cytochrome c, an electron acceptor alternative to oxygen. On the basis of the results obtained, a chemical mechanism of phosphorylation is proposed in which the free radical form of reduced flavin sensitizer left( {{text{FlH}}^ bullet } right) and ADP are involved.

Kolesnikov, Michael P.; Telegina, Taisiya A.; Lyudnikova, Tamara A.; Kritsky, Mikhail S.

2008-06-01

202

Chemistry & Biology ATP-Independent Control of Autotransporter  

E-print Network

autonomously catalyzes transport of its own passenger across the OM (Loveless and Saier, 1997; Henderson et alChemistry & Biology Article ATP-Independent Control of Autotransporter Virulence Protein Transport between localized regions of stability (DGfolding) in the mature virulence protein (the AT ``passenger

Clark, Patricia L.

203

ATP drives direct photosynthetic production of 1-butanol in cyanobacteria  

PubMed Central

While conservation of ATP is often a desirable trait for microbial production of chemicals, we demonstrate that additional consumption of ATP may be beneficial to drive product formation in a nonnatural pathway. Although production of 1-butanol by the fermentative coenzyme A (CoA)-dependent pathway using the reversal of ?-oxidation exists in nature and has been demonstrated in various organisms, the first step of the pathway, condensation of two molecules of acetyl-CoA to acetoacetyl-CoA, is thermodynamically unfavorable. Here, we show that artificially engineered ATP consumption through a pathway modification can drive this reaction forward and enables for the first time the direct photosynthetic production of 1-butanol from cyanobacteria Synechococcus elongatus PCC 7942. We further demonstrated that substitution of bifunctional aldehyde/alcohol dehydrogenase (AdhE2) with separate butyraldehyde dehydrogenase (Bldh) and NADPH-dependent alcohol dehydrogenase (YqhD) increased 1-butanol production by 4-fold. These results demonstrated the importance of ATP and cofactor driving forces as a design principle to alter metabolic flux. PMID:22474341

Lan, Ethan I.; Liao, James C.

2012-01-01

204

Interaction between ATP, metal ions, glycine, and several minerals  

NASA Technical Reports Server (NTRS)

Interactions between ATP, glycine and montmorillonite and kaolinite clay minerals in the presence of various metal cations are investigated. The adsorption of adenine nucleotides on clays and Al(OH)3 was measured as a function of pH, and glycine condensation was followed in the presence of ATP, ZnCl2, MgCl2 and either kaolinite or montmorillonite. The amounts of ATP and ADP adsorbed are found to decrease with increasing Ph, and to be considerably enhanced in experiments with Mg(2+)- and Zn(2+)-montmorillonite with respect to Na(+)-montmorillonite. The effects of divalent cations are less marked in kaolinite. Results for Al(OH)3 show the importance of adsorption at clay platelet edges at high pH. The decomposition of ATP during drying at high temperature is observed to be inhibited by small amounts of clay, vacuum, or Mg(2+) or Zn(2+) ions, and to be accompanied by peptide formation in the presence of glycine. Results suggest the importance of Zn(2+) and Mg(2+) in chemical evolution.

Rishpon, J.; Ohara, P. J.; Lawless, J. G.; Lahav, N.

1982-01-01

205

ATP6V0D1/A0403  

NSDL National Science Digital Library

ATPase, proton-transporting, lysosomal V0 subunit D1 (ATP6V0D1, also known as A0403) is responsible for the acidification of endosomes, lysosomes, and other intracellular organelles in eukaryotic cells, thus providing most of the energy required for ...

2009-04-14

206

Treatment of heterotopic ossification through remote ATP hydrolysis  

PubMed Central

Heterotopic ossification (HO) is the pathologic development of ectopic bone in soft tissues because of a local or systemic inflammatory insult, such as burn injury or trauma. In HO, mesenchymal stem cells (MSCs) are inappropriately activated to undergo osteogenic differentiation. Through the correlation of in vitro assays and in vivo studies (dorsal scald burn with Achilles tenotomy), we have shown that burn injury enhances the osteogenic potential of MSCs and causes ectopic endochondral heterotopic bone formation and functional contractures through bone morphogenetic protein–mediated canonical SMAD signaling. We further demonstrated a prevention strategy for HO through adenosine triphosphate (ATP) hydrolysis at the burn site using apyrase. Burn site apyrase treatment decreased ATP, increased adenosine 3?,5?-monophosphate, and decreased phosphorylation of SMAD1/5/8 in MSCs in vitro. This ATP hydrolysis also decreased HO formation and mitigated functional impairment in vivo. Similarly, selective inhibition of SMAD1/5/8 phosphorylation with LDN-193189 decreased HO formation and increased range of motion at the injury site in our burn model in vivo. Our results suggest that burn injury–exacerbated HO formation can be treated through therapeutics that target burn site ATP hydrolysis and modulation of SMAD1/5/8 phosphorylation. PMID:25253675

Peterson, Jonathan R.; De La Rosa, Sara; Eboda, Oluwatobi; Cilwa, Katherine E.; Agarwal, Shailesh; Buchman, Steven R.; Cederna, Paul S.; Xi, Chuanwu; Morris, Michael D.; Herndon, David N.; Xiao, Wenzhong; Tompkins, Ronald G.; Krebsbach, Paul H.; Wang, Stewart C.; Levi, Benjamin

2015-01-01

207

ATP Interior Noise Technology and Flight Demonstration Program  

NASA Technical Reports Server (NTRS)

The paper provides an overview of the ATP (Advanced Turboprop Program) acoustics program with emphasis on the NASA technology program and the recent NASA/Industry demonstration programs aimed at understanding and controlling passenger cabin noise. Technology developments in propeller (source) noise, cabin noise transmission, and subjective acoustics are described. Finally, an overview of the industry demonstrator programs is presented.

Stephens, David G.; Powell, Clemans A.

1988-01-01

208

Rapid and precise determination of ATP using a modified photometer  

USGS Publications Warehouse

An inexpensive delay timer was designed to modify a commercially available ATP photometer which allows a disposable tip pipette to be used for injecting either enzyme or sample into the reaction cuvette. The disposable tip pipette is as precise and accurate as a fixed-needle syringe but eliminates the problem of sample contamination and decreases analytical time. (USGS)

Shultz, David J.; Stephens, Doyle W.

1980-01-01

209

Teacher Development for ATP 2000. Project Report 1993-1994.  

ERIC Educational Resources Information Center

Agri Tech Prep 2000 (ATP 2000) is a 4-year tech prep program intended to link high school and postsecondary curricula preparing New York students for careers in agriculture or acceptance into a college program in agriculture. Because teacher development was designated an integral project component for fiscal year 1992-93, a weeklong teacher…

Newsom-Stewart, Mhora; Sutphin, Dean

210

Teacher Development Program for ATP 2000. Project Report.  

ERIC Educational Resources Information Center

Agri Tech Prep 2000 (ATP 2000) is a 4-year tech prep program linking high school and postsecondary curricula designed to prepare New York students for careers in agriculture or acceptance into a college program in agriculture. Because teacher development was designated an integral project component for fiscal year 1991-1992, a weeklong teacher…

Sutphin, Dean; And Others

211

Updated 19 March 2009 PHD TOPICS AVAILABLE AT NICTA, ATP  

E-print Network

Theme at ATP Title: Multimodal Signal Processing for Cognitive Load Measurement Contact: Fang Chen Measurement Based on EEG Signal Processing Contact: Fang Chen Although human cognitive load is well understood perceived by a human. Intelligent Decision Support for Incident Management Contact: Fang Chen Decision

Heiser, Gernot

212

ATP Binding Turns Plant Cryptochrome Into an Efficient Natural Photoswitch  

PubMed Central

Cryptochromes are flavoproteins that drive diverse developmental light-responses in plants and participate in the circadian clock in animals. Plant cryptochromes have found application as photoswitches in optogenetics. We have studied effects of pH and ATP on the functionally relevant photoreduction of the oxidized FAD cofactor to the semi-reduced FADH· radical in isolated Arabidopsis cryptochrome 1 by transient absorption spectroscopy on nanosecond to millisecond timescales. In the absence of ATP, the yield of light-induced radicals strongly decreased with increasing pH from 6.5 to 8.5. With ATP present, these yields were significantly higher and virtually pH-independent up to pH 9. Analysis of our data in light of the crystallographic structure suggests that ATP-binding shifts the pKa of aspartic acid D396, the putative proton donor to FAD·?, from ~7.4 to >9, and favours a reaction pathway yielding long-lived aspartate D396?. Its negative charge could trigger conformational changes necessary for signal transduction. PMID:24898692

Müller, Pavel; Bouly, Jean-Pierre; Hitomi, Kenichi; Balland, Véronique; Getzoff, Elizabeth D.; Ritz, Thorsten; Brettel, Klaus

2014-01-01

213

7 CFR 3300.4 - Definitions.  

Code of Federal Regulations, 2010 CFR

...EQUIPMENT TO BE USED FOR SUCH CARRIAGE (ATP); INSPECTION, TESTING, AND CERTIFICATION...Street, SW., Washington, DC 20250. ATP means the Agreement on the International...Equipment to be Used for Such Carriage (ATP), and the annexes and appendices...

2010-01-01

214

Distinct Wilson-disease mutations in ATP7B are associated with enhanced binding to COMMD1 and reduced stability of ATP7B  

PubMed Central

Background/Aims Wilson disease is characterized by hepatic copper overload and caused by mutations in the gene encoding the copper transporting P-type ATPase ATP7B. ATP7B interacts with COMMD1, a protein that is deleted in Bedlington terriers with hereditary copper toxicosis. Here we characterized the implications of the interaction between COMMD1 and ATP7B in relation to the pathogenesis of Wilson disease. Methods GST pull-down experiments, co-immunoprecipitations, immunofluoresensce microscopy, site-directed mutagenesis and biosynthetic labeling experiments were performed to characterize the interaction between COMMD1 and ATP7B and the effects of Wilson disease causing mutations. Results COMMD1 specifically interacted with the amino-terminal region of ATP7B. This interaction was independent of intracellular copper levels and of the expression of the copper chaperone ATOX1. Four Wilson disease patient derived mutations in this region of ATP7B significantly increased its binding to COMMD1. Two of these mutations also resulted in mislocalization and increased degradation rate of ATP7B. Although COMMD1 did not affect copper-induced trafficking of ATP7B, it markedly decreased the stability of newly synthesized ATP7B. Conclusions Our data implicate COMMD1 in the pathogenesis of Wilson disease and indicate that COMMD1 exerts its regulatory role in copper homeostasis through the regulation of ATP7B stability. PMID:17919502

de Bie, Prim; van de Sluis, Bart; Burstein, Ezra; van de Berghe, Peter V.E.; Muller, Patricia; Berger, Ruud; Gitlin, Jonathan D.; Wijmenga, Cisca; Klomp, Leo W.J.

2008-01-01

215

15 CFR 295.11 - Technical and educational services for ATP recipients.  

Code of Federal Regulations, 2011 CFR

...false Technical and educational services for ATP recipients...11 Technical and educational services for ATP recipients...equipment, or other resources except funds toward...and undertake other educational activities to foster...with other funding resources for purposes of...

2011-01-01

216

15 CFR 295.11 - Technical and educational services for ATP recipients.  

Code of Federal Regulations, 2013 CFR

...false Technical and educational services for ATP recipients...11 Technical and educational services for ATP recipients...equipment, or other resources except funds toward...and undertake other educational activities to foster...with other funding resources for purposes of...

2013-01-01

217

15 CFR 295.11 - Technical and educational services for ATP recipients.  

Code of Federal Regulations, 2012 CFR

...false Technical and educational services for ATP recipients...11 Technical and educational services for ATP recipients...equipment, or other resources except funds toward...and undertake other educational activities to foster...with other funding resources for purposes of...

2012-01-01

218

15 CFR 295.11 - Technical and educational services for ATP recipients.  

Code of Federal Regulations, 2014 CFR

...false Technical and educational services for ATP recipients...11 Technical and educational services for ATP recipients...equipment, or other resources except funds toward...and undertake other educational activities to foster...with other funding resources for purposes of...

2014-01-01

219

Metabolomic Analysis of Differential Changes in Metabolites during ATP Oscillations in Chondrogenesis  

PubMed Central

Prechondrogenic condensation is a critical step for skeletal pattern formation. Recent studies reported that ATP oscillations play an essential role in prechondrogenic condensation. However, the molecular mechanism to underlie ATP oscillations remains poorly understood. In the present study, it was investigated how changes in metabolites are implicated in ATP oscillations during chondrogenesis by using capillary electrophoresis time-of-flight mass spectrometry (CE-TOF-MS). CE-TOF-MS detected 93 cationic and 109 anionic compounds derived from known metabolic pathways. 15 cationic and 18 anionic compounds revealed significant change between peak and trough of ATP oscillations. These results implicate that glycolysis, mitochondrial respiration and uronic acid pathway oscillate in phase with ATP oscillations, while PPRP and nucleotides synthesis pathways oscillate in antiphase with ATP oscillations. This suggests that the ATP-producing glycolysis and mitochondrial respiration oscillate in antiphase with the ATP-consuming PPRP/nucleotide synthesis pathway during chondrogenesis. PMID:23878799

Ohmiya, Yoshihiro

2013-01-01

220

Studies of the C-terminal Region of the Gamma Subunit of the Chloroplast ATP Synthase  

E-print Network

" is not required for ATP hydrolysis but critical for proton coupling and ATP synthesis functions. Nucleotide binding and exchange studies using TNP-ADP showed that substituting three residues in the "catch" region simultaneously inhibited the nucleotide exchange...

He, Feng

2008-06-18

221

Regulation of Extracellular ATP in Human Erythrocytes Infected with Plasmodium falciparum  

PubMed Central

In human erythrocytes (h-RBCs) various stimuli induce increases in [cAMP] that trigger ATP release. The resulting pattern of extracellular ATP accumulation (ATPe kinetics) depends on both ATP release and ATPe degradation by ectoATPase activity. In this study we evaluated ATPe kinetics from primary cultures of h-RBCs infected with P. falciparum at various stages of infection (ring, trophozoite and schizont stages). A “3V” mixture containing isoproterenol (?-adrenergic agonist), forskolin (adenylate kinase activator) and papaverine (phosphodiesterase inhibitor) was used to induce cAMP-dependent ATP release. ATPe kinetics of r-RBCs (ring-infected RBCs), t-RBCs (trophozoite-infected RBCs) and s-RBCs (schizont-infected RBCs) showed [ATPe] to peak acutely to a maximum value followed by a slower time dependent decrease. In all intraerythrocytic stages, values of ?ATP1 (difference between [ATPe] measured 1 min post-stimulus and basal [ATPe]) increased nonlinearly with parasitemia (from 2 to 12.5%). Under 3V exposure, t-RBCs at parasitemia 94% (t94-RBCs) showed 3.8-fold higher ?ATP1 values than in h-RBCs, indicative of upregulated ATP release. Pre-exposure to either 100 µM carbenoxolone, 100 nM mefloquine or 100 µM NPPB reduced ?ATP1 to 83–87% for h-RBCs and 63–74% for t94-RBCs. EctoATPase activity, assayed at both low nM concentrations (300–900 nM) and 500 µM exogenous ATPe concentrations increased approx. 400-fold in t94-RBCs, as compared to h-RBCs, while intracellular ATP concentrations of t94-RBCs were 65% that of h-RBCs. In t94-RBCs, production of nitric oxide (NO) was approx. 7-fold higher than in h-RBCs, and was partially inhibited by L-NAME pre-treatment. In media with L-NAME, ?ATP1 values were 2.7-times higher in h-RBCs and 4.2-times higher in t94-RBCs, than without L-NAME. Results suggest that P. falciparum infection of h-RBCs strongly activates ATP release via Pannexin 1 in these cells. Several processes partially counteracted ATPe accumulation: an upregulated ATPe degradation, an enhanced NO production, and a decreased intracellular ATP concentration. PMID:24858837

Alvarez, Cora Lilia; Schachter, Julieta; de Sá Pinheiro, Ana Acacia; Silva, Leandro de Souza; Verstraeten, Sandra Viviana; Persechini, Pedro Muanis; Schwarzbaum, Pablo Julio

2014-01-01

222

Interactions of ATP, oestradiol, genistein and the anti-oestrogens, faslodex (ICI 182780) and tamoxifen, with the human erythrocyte glucose transporter, GLUT1.  

PubMed Central

17 beta-Oestradiol (ED when subscript to K) and the phytoestrogen isoflavone genistein (GEN) inhibit glucose transport in human erythrocytes and erythrocyte ghosts. The selective oestrogen receptor modulators or anti-oestrogens, faslodex (ICI 182780) (FAS) and tamoxifen (TAM), competitively antagonize oestradiol inhibition of glucose exit from erythrocytes (K(i(ED/FAS))=2.84+/-0.16 microM and K(i(ED/TAM))=100+/-2 nM). Faslodex has no significant inhibitory effect on glucose exit, but tamoxifen alone inhibits glucose exit (K(i(TAM))=300+/-100 nM). In ghosts, ATP (1-4 mM) competitively antagonizes oestradiol, genistein and cytochalasin B (CB)-dependent inhibitions of glucose exit, (K(i(ATP/ED))=2.5+/-0.23 mM, K(i(ATP/GEN))=0.99+/-0.17 mM and K(i(ATP/CB))=0.76+/-0.08 mM). Tamoxifen and faslodex reverse oestradiol-dependent inhibition of glucose exit with ATP>1 mM (K(i(ED/TAM))=130+/-5 nM and K(i(ED/FAS))=2.7+/-0.9 microM). The cytoplasmic surface of the glucose transporter (GLUT)1 contains four sequences with close homologies to sequences in the ligand-binding domain of human oestrogen receptor beta (hesr-2). One homology is adjacent to the Walker ATP-binding motif II (GLUT1, residues 225-229) in the large cytoplasmic segment linking transmembrane helices 6 and 7; another GLUT (residues 421-423) contains the Walker ATP-binding motif III. Mapping of these regions on to a three-dimensional template of GLUT indicates that a possible oestrogen-binding site lies between His(337), Arg(349) and Glu(249) at the cytoplasmic entrance to the hydrophilic pore spanning GLUT, which have a similar topology to His(475), Glu(305) and Arg(346) in hesr-2 that anchor the head and tail hydroxy groups of oestradiol and genistein, and thus are suitably placed to provide an ATP-sensitive oestrogen binding site that could modulate glucose export. PMID:12133004

Afzal, Iram; Cunningham, Philip; Naftalin, Richard J

2002-01-01

223

ATP pools and transients in the blue-green alga, Anabaena cylindrica  

Microsoft Academic Search

Anabaena cylindrica grown in steady state continuous culture has an extractable ATP pool, measured on the basis of the luciferin-luciferase assay of 165±35 nmoles ATP mg chla-1. This pool is maintained by a dynamic balance between the rate of ATP synthesis and the rate of ATP utilization. Phosphorylating mechanisms which can maintain the pool in the short term are total

P. J. Bottomley; W. D. P. Stewart

1976-01-01

224

Mechanical effects of muscle contraction increase intravascular ATP draining quiescent and active skeletal muscle in humans  

PubMed Central

Intravascular adenosine triphosphate (ATP) evokes vasodilation and is implicated in the regulation of skeletal muscle blood flow during exercise. Mechanical stresses to erythrocytes and endothelial cells stimulate ATP release in vitro. How mechanical effects of muscle contractions contribute to increased plasma ATP during exercise is largely unexplored. We tested the hypothesis that simulated mechanical effects of muscle contractions increase [ATP]venous and ATP effluent in vivo, independent of changes in tissue metabolic demand, and further increase plasma ATP when superimposed with mild-intensity exercise. In young healthy adults, we measured forearm blood flow (FBF) (Doppler ultrasound) and plasma [ATP]v (luciferin-luciferase assay), then calculated forearm ATP effluent (FBF×[ATP]v) during rhythmic forearm compressions (RFC) via a blood pressure cuff at three graded pressures (50, 100, and 200 mmHg; Protocol 1; n = 10) and during RFC at 100 mmHg, 5% maximal voluntary contraction rhythmic handgrip exercise (RHG), and combined RFC + RHG (Protocol 2; n = 10). [ATP]v increased from rest with each cuff pressure (range 144–161 vs. 64 ± 13 nmol/l), and ATP effluent was graded with pressure. In Protocol 2, [ATP]v increased in each condition compared with rest (RFC: 123 ± 33; RHG: 51 ± 9; RFC + RHG: 96 ± 23 vs. Mean Rest: 42 ± 4 nmol/l; P < 0.05), and ATP effluent was greatest with RFC + RHG (RFC: 5.3 ± 1.4; RHG: 5.3 ± 1.1; RFC + RHG: 11.6 ± 2.7 vs. Mean Rest: 1.2 ± 0.1 nmol/min; P < 0.05). We conclude that the mechanical effects of muscle contraction can 1) independently elevate intravascular ATP draining quiescent skeletal muscle without changes in local metabolism and 2) further augment intravascular ATP during mild exercise associated with increases in metabolism and local deoxygenation; therefore, it is likely one stimulus for increasing intravascular ATP during exercise in humans. PMID:23429876

Crecelius, Anne R.; Kirby, Brett S.; Richards, Jennifer C.

2013-01-01

225

Timely management of developing class III malocclusion.  

PubMed

Timing of orthodontic treatment, especially for children with developing class III malocclusions, has always been somewhat controversial, and definitive treatment tends to be delayed for severe class III cases. Developing class III patients with moderate to severe anterior crossbite and deep bite may need early intervention in some selected cases. Class III malocclusion may develop in children as a result of an inherent growth abnormality, i.e. true class III malocclusion, or as a result of premature occlusal contacts causing forward functional shift of the mandible, which is known as pseudo class III malocclusion. These cases, if not treated at the initial stage of development, interfere with normal growth of the jaw bases and may result in severe facial deformities. The treatment should be carried out as early as possible for permitting normal growth of the skeletal bases. This paper deals with the selection of an appropriate appliance from the various current options available for early intervention in developing class III malocclusion through two case reports. PMID:22565523

Yelampalli, M R; Rachala, M R

2012-01-01

226

Cytotoxicity of mitochondria-targeted resveratrol derivatives: interactions with respiratory chain complexes and ATP synthase.  

PubMed

We recently reported that mitochondria-targeted derivatives of resveratrol are cytotoxic in vitro, selectively inducing mostly necrotic death of fast-growing and tumoral cells when supplied in the low ?M range (N. Sassi et al., Curr. Pharm. Des. 2014). Cytotoxicity is due to H2O2 produced upon accumulation of the compounds into mitochondria. We investigate here the mechanisms underlying ROS generation and mitochondrial depolarization caused by these agents. We find that they interact with the respiratory chain, especially complexes I and III, causing superoxide production. "Capping" free hydroxyls with acetyl or methyl groups increases their effectiveness as respiratory chain inhibitors, promoters of ROS generation and cytotoxic agents. Exposure to the compounds also induces an increase in the occurrence of short transient [Ca(2+)] "spikes" in the cells. This increase is unrelated to ROS production, and it is not the cause of cell death. These molecules furthermore inhibit the F0F1 ATPase. When added to oligomycin-treated cells, the acetylated/methylated ones cause a recovery of the cellular oxygen consumption rates depressed by oligomycin. Since a protonophoric futile cycle which might account for the uncoupling effect is impossible, we speculate that the compounds may cause the transformation of the ATP synthase and/or respiratory chain complex(es) into a conduit for uncoupled proton translocation. Only in the presence of excess oligomycin the most effective derivatives appear to induce the mitochondrial permeability transition (MPT) within the cells. This may be considered to provide circumstantial support for the idea that the ATP synthase is the molecular substrate for the MPT pore. PMID:24997425

Sassi, Nicola; Mattarei, Andrea; Azzolini, Michele; Szabo', Ildiko'; Paradisi, Cristina; Zoratti, Mario; Biasutto, Lucia

2014-10-01

227

Subtype-specific control of P2X receptor channel signaling by ATP and Mg2+  

PubMed Central

The identity and forms of activating ligands for ion channels are fundamental to their physiological roles in rapid electrical signaling. P2X receptor channels are ATP-activated cation channels that serve important roles in sensory signaling and inflammation, yet the active forms of the nucleotide are unknown. In physiological solutions, ATP is ionized and primarily found in complex with Mg2+. Here we investigated the active forms of ATP and found that the action of MgATP2? and ATP4? differs between subtypes of P2X receptors. The slowly desensitizing P2X2 receptor can be activated by free ATP, but MgATP2? promotes opening with very low efficacy. In contrast, both free ATP and MgATP2? robustly open the rapidly desensitizing P2X3 subtype. A further distinction between these two subtypes is the ability of Mg2+ to regulate P2X3 through a distinct allosteric mechanism. Importantly, heteromeric P2X2/3 channels present in sensory neurons exhibit a hybrid phenotype, characterized by robust activation by MgATP2? and weak regulation by Mg2+. These results reveal the existence of two classes of homomeric P2X receptors with differential sensitivity to MgATP2? and regulation by Mg2+, and demonstrate that both restraining mechanisms can be disengaged in heteromeric channels to form fast and sensitive ATP signaling pathways in sensory neurons. PMID:23959888

Li, Mufeng; Silberberg, Shai D.; Swartz, Kenton J.

2013-01-01

228

ATP monitoring technology for microbial growth control in potable water systems  

Microsoft Academic Search

ATP (Adenosine Triphosphate) is the primary energy transfer molecule present in all living biological cells on Earth. ATP cannot be produced or maintained by anything but a living organism, and as such, its measurement is a direct indication of biological activity. The main advantage of ATP as a biological indicator is the speed of the analysis - from collecting the

Patrick A. Whalen; Philip J. Whalen; James E. Cairns

2006-01-01

229

Inhibition of the ATPase activity of Escherichia coli ATP synthase by magnesium fluoride  

E-print Network

Inhibition of the ATPase activity of Escherichia coli ATP synthase by magnesium fluoride Zulfiqar activity of Escherichia coli ATP synthase by magnesium fluoride (MgFx) was studied. Wild-type F1-ATPase synthesis mechanism; Magnesium fluoride; ATPase inhibition; Transition state analog 1. Introduction ATP

Zulfiqar Ahmad

230

Mechanisms underlying postjunctional synergism between responses of the vas deferens to noradrenaline and ATP  

E-print Network

of postjunctional synergism between adenosine 5V-triphosphate (ATP) and noradrenaline were studied in isolated of protein kinase C (PKC), failed to induce contractions, it significantly potentiated ATP; PKC 1. Introduction Although the sympathetic cotransmitters adenosine 5V- triphosphate (ATP

Burnstock, Geoffrey

231

7 CFR 3300.88 - Fees for U.S. ATP certificates.  

Code of Federal Regulations, 2010 CFR

...2010-01-01 false Fees for U.S. ATP certificates. 3300.88 Section 3300...EQUIPMENT TO BE USED FOR SUCH CARRIAGE (ATP); INSPECTION, TESTING, AND CERTIFICATION...Provisions § 3300.88 Fees for U.S. ATP certificates. The fee schedule for...

2010-01-01

232

76 FR 13069 - Airworthiness Directives; BAE Systems (Operations) Limited Model ATP Airplanes; BAE Systems...  

Federal Register 2010, 2011, 2012, 2013, 2014

...BAE Systems (Operations) Limited Model ATP Airplanes; BAE Systems (Operations) Limited...The MCAI states: Early in the life of the ATP (circa 1989), a report was received that...contact. BAE Systems responded by issuing SB ATP- 27-11, describing a one-time...

2011-03-10

233

Characterization of an ATP translocase identified in the plant pathogen, Candidatus Liberibacter asiaticus  

Technology Transfer Automated Retrieval System (TEKTRAN)

ATP/ADP translocases allow for the transport of ATP across a lipid bilayer, which is normally impermeable to this molecule due to its size and charge. These transport proteins appear to be unique to mitochondria, plant plastids, and obligate-intracellular bacteria. Of the bacterial ATP/ADP translo...

234

The extent of mitochondrial F1-ATPase and adenine nucleotide carrier activity with epsilon-ATP.  

PubMed

1. The use of 1,N6-ethenoadenosine 5'-triphosphate (epsilon-ATP), a synthetic, fluorescent analog of ATP, by whole rat liver mitochondria and by submitochondrial particles produced via sonication has been studied. 2. Direct [3H]adenine nucleotide uptake studies with isolated mitochondria, indicate the epsilon-[3H]ATP is not transported through the inner membrane by the adenine nucleotide carrier and is therefore not utilized by the 2,4-dinitrophenol-sensitive F1-ATPase (EC 3.6.1.3) that functions in oxidative phosphorylation. However, epsilon-ATP is hydrolyzed by a Mg2+-dependent, 2,4-dinitrophenol-insensitive ATPase that is characteristic of damaged mitochondria. 3. epsilon-ATP can be utilized quite well by the exposed F1-ATPase of sonic submitochondrial particles. This epsilon-ATP hydrolysis activity is inhibited by oligomycin and stimulated by 2,4-dinitrophenol. The particle F1-ATPase displays similar Km values for both ATP and epsilon-ATP; however, the V with ATP is approximately six times greater than with epsilon-ATP. 4. Since epsilon-ATP is a capable substrate for the submitochondrial particle F1-ATPase, it is proposed that the fluorescent properties of this ATP analog might be employed to study the submitochondrial particle F1-ATPase complex, and its response to various modifiers of oxidative phosphorylation. PMID:145875

Kaplan, R S; Coleman, P S

1978-02-01

235

Temperature Effects on the Allosteric Transition of ATP Sulfurylase from Penicillium chrysogenum1  

E-print Network

Temperature Effects on the Allosteric Transition of ATP Sulfurylase from Penicillium chrysogenum1 sulfurylase from Penicillium chrysogenum were measured. The experiments were prompted by the structuralATP APS ª PAPS MgADP APS kinase ATP sulfurylase from Penicillium chrysogenum is an oligomer composed

Fisher, Andrew J.

236

Plasma ATP concentration and venous oxygen content in the forearm during dynamic handgrip exercise  

Microsoft Academic Search

BACKGROUND: It has been proposed that adenosine triphosphate (ATP) released from red blood cells (RBCs) may contribute to the tight coupling between blood flow and oxygen demand in contracting skeletal muscle. To determine whether ATP may contribute to the vasodilatory response to exercise in the forearm, we measured arterialised and venous plasma ATP concentration and venous oxygen content in 10

Rachel E Wood; Connie Wishart; Philip J Walker; Christopher D Askew; Ian B Stewart

2009-01-01

237

ATP increases within the lumen of the endoplasmic reticulum upon intracellular Ca2+ release  

PubMed Central

Multiple functions of the endoplasmic reticulum (ER) essentially depend on ATP within this organelle. However, little is known about ER ATP dynamics and the regulation of ER ATP import. Here we describe real-time recordings of ER ATP fluxes in single cells using an ER-targeted, genetically encoded ATP sensor. In vitro experiments prove that the ATP sensor is both Ca2+ and redox insensitive, which makes it possible to monitor Ca2+-coupled ER ATP dynamics specifically. The approach uncovers a cell type–specific regulation of ER ATP homeostasis in different cell types. Moreover, we show that intracellular Ca2+ release is coupled to an increase of ATP within the ER. The Ca2+-coupled ER ATP increase is independent of the mode of Ca2+ mobilization and controlled by the rate of ATP biosynthesis. Furthermore, the energy stress sensor, AMP-activated protein kinase, is essential for the ATP increase that occurs in response to Ca2+ depletion of the organelle. Our data highlight a novel Ca2+-controlled process that supplies the ER with additional energy upon cell stimulation. PMID:24307679

Vishnu, Neelanjan; Jadoon Khan, Muhammad; Karsten, Felix; Groschner, Lukas N.; Waldeck-Weiermair, Markus; Rost, Rene; Hallström, Seth; Imamura, Hiromi; Graier, Wolfgang F.; Malli, Roland

2014-01-01

238

Failure of the Cystic Fibrosis Transmembrane Conductance Regulator to Conduct ATP  

Microsoft Academic Search

The cystic fibrosis transmembrane conductance regulator (CFTR) is chloride ion channel regulated by protein kinase A and adenosine triphosphate (ATP). Loss of CFTR-mediated chloride ion conductance from the apical plasma membrane of epithelial cells is a primary physiological lesion in cystic fibrosis. CFTR has also been suggested to function as an ATP channel, although the size of the ATP anion

M. M. Reddy; P. M. Quinton; C. Haws; J. J. Wine; R. Grygorczyk; J. A. Tabcharani; J. W. Hanrahan; K. L. Gunderson; R. R. Kopito

1996-01-01

239

Responses of Rat P2X2 Receptors to Ultrashort Pulses of ATP Provide Insights into ATP Binding and Channel Gating  

PubMed Central

To gain insight into the way that P2X2 receptors localized at synapses might function, we explored the properties of outside-out patches containing many of these channels as ATP was very rapidly applied and removed. Using a new method to calibrate the speed of exchange of solution over intact patches, we were able to reliably produce applications of ATP lasting <200 ?s. For all concentrations of ATP, there was a delay of at least 80 ?s between the time when ATP arrived at the receptor and the first detectable flow of inward current. In response to 200-?s pulses of ATP, the time constant of the rising phase of the current was ?600 ?s. Thus, most channel openings occurred when no free ATP was present. The current deactivated with a time constant of ?60 ms. The amplitude of the peak response to a brief pulse of a saturating concentration of ATP was ?70% of that obtained during a long application of the same concentration of ATP. Thus, ATP leaves fully liganded channels without producing an opening at least 30% of the time. Extensive kinetic modeling revealed three different schemes that fit the data well, a sequential model and two allosteric models. To account for the delay in opening at saturating ATP, it was necessary to incorporate an intermediate closed state into all three schemes. These kinetic properties indicate that responses to ATP at synapses that use homomeric P2X2 receptors would be expected to greatly outlast the duration of the synaptic ATP transient produced by a single presynaptic spike. Like NMDA receptors, P2X2 receptors provide the potential for complex patterns of synaptic integration over a time scale of hundreds of milliseconds. PMID:17664346

Moffatt, Luciano; Hume, Richard I.

2007-01-01

240

TCDD decreases ATP levels and increases reactive oxygen production through changes in mitochondrial F 0F 1ATP synthase and ubiquinone  

Microsoft Academic Search

Mitochondria generate ATP and participate in signal transduction and cellular pathology and\\/or cell death. TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) decreases hepatic ATP levels and generates mitochondrial oxidative DNA damage, which is exacerbated by increasing mitochondrial glutathione redox state and by inner membrane hyperpolarization. This study identifies mitochondrial targets of TCDD that initiate and sustain reactive oxygen production and decreased ATP levels. One week

Howard G.. Shertzer; Mary Beth Genter; Dongxiao Shen; Daniel W. Nebert; Ying Chen; Timothy P. Dalton

2006-01-01

241

ATPase-Independent Type-III Protein Secretion in Salmonella enterica  

PubMed Central

Type-III protein secretion systems are utilized by gram-negative pathogens to secrete building blocks of the bacterial flagellum, virulence effectors from the cytoplasm into host cells, and structural subunits of the needle complex. The flagellar type-III secretion apparatus utilizes both the energy of the proton motive force and ATP hydrolysis to energize substrate unfolding and translocation. We report formation of functional flagella in the absence of type-III ATPase activity by mutations that increased the proton motive force and flagellar substrate levels. We additionally show that increased proton motive force bypassed the requirement of the Salmonella pathogenicity island 1 virulence-associated type-III ATPase for secretion. Our data support a role for type-III ATPases in enhancing secretion efficiency under limited secretion substrate concentrations and reveal the dispensability of ATPase activity in the type-III protein export process. PMID:25393010

Erhardt, Marc; Mertens, Max E.; Fabiani, Florian D.; Hughes, Kelly T.

2014-01-01

242

TCDD decreases ATP levels and increases reactive oxygen production through changes in mitochondrial F F{sub 1}-ATP synthase and ubiquinone  

SciTech Connect

Mitochondria generate ATP and participate in signal transduction and cellular pathology and/or cell death. TCDD (2,3,7,8-tetrachlorodibenzo-p-dioxin) decreases hepatic ATP levels and generates mitochondrial oxidative DNA damage, which is exacerbated by increasing mitochondrial glutathione redox state and by inner membrane hyperpolarization. This study identifies mitochondrial targets of TCDD that initiate and sustain reactive oxygen production and decreased ATP levels. One week after treating mice with TCDD, liver ubiquinone (Q) levels were significantly decreased, while rates of succinoxidase and Q-cytochrome c oxidoreductase activities were increased. However, the expected increase in Q reduction state following TCDD treatment did not occur; instead, Q was more oxidized. These results could be explained by an ATP synthase defect, a premise supported by the unusual finding that TCDD lowers ATP/O ratios without concomitant changes in respiratory control ratios. Such results suggest either a futile cycle in ATP synthesis, or hydrolysis of newly synthesized ATP prior to release. The TCDD-mediated decrease in Q, concomitant with an increase in respiration, increases complex 3 redox cycling. This acts in concert with glutathione to increase membrane potential and reactive oxygen production. The proposed defect in ATP synthase explains both the greater respiratory rates and the lower tissue ATP levels.

Shertzer, Howard G. [Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, P.O. Box 670056 Cincinnati, OH 45267-0056 (United States)]. E-mail: shertzhg@ucmail.uc.edu; Genter, Mary Beth [Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, P.O. Box 670056 Cincinnati, OH 45267-0056 (United States); Shen, Dongxiao [Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, P.O. Box 670056 Cincinnati, OH 45267-0056 (United States); Nebert, Daniel W. [Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, P.O. Box 670056 Cincinnati, OH 45267-0056 (United States); Chen, Ying [Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, P.O. Box 670056 Cincinnati, OH 45267-0056 (United States); Dalton, Timothy P. [Department of Environmental Health and Center for Environmental Genetics, University of Cincinnati Medical Center, P.O. Box 670056 Cincinnati, OH 45267-0056 (United States)

2006-12-15

243

Selectivity of TMC207 towards Mycobacterial ATP Synthase Compared with That towards the Eukaryotic Homologue?  

PubMed Central

The diarylquinoline TMC207 kills Mycobacterium tuberculosis by specifically inhibiting ATP synthase. We show here that human mitochondrial ATP synthase (50% inhibitory concentration [IC50] of >200 ?M) displayed more than 20,000-fold lower sensitivity for TMC207 compared to that of mycobacterial ATP synthase (IC50 of 10 nM). Also, oxygen consumption in mouse liver and bovine heart mitochondria showed very low sensitivity for TMC207. These results suggest that TMC207 may not elicit ATP synthesis-related toxicity in mammalian cells. ATP synthase, although highly conserved between prokaryotes and eukaryotes, may still qualify as an attractive antibiotic target. PMID:19075053

Haagsma, Anna C.; Abdillahi-Ibrahim, Rooda; Wagner, Marijke J.; Krab, Klaas; Vergauwen, Karen; Guillemont, Jerome; Andries, Koen; Lill, Holger; Koul, Anil; Bald, Dirk

2009-01-01

244

Structural Analysis of ATP Analogs Compatible with Kinase-Catalyzed Labeling  

PubMed Central

Kinase-catalyzed protein phosphorylation is an important biochemical process involved in cellular functions. We recently discovered that kinases promiscuously accept ?-modified ATP analogs as cosubstrates and used several ATP analogs as tools for studying protein phosphorylation. Herein, we explore the structural requirements of ?-modified ATP analogs for kinase compatibility. To understand the influence of linker length and composition, a series of ATP analogs was synthesized and the efficiency of kinase-catalyzed labeling was determined by quantitative mass spectrometry. This study on factors influencing kinase cosubstrate promiscuity will enable design of ATP analogs for a variety of kinase-catalyzed labeling reactions. PMID:23116557

Suwal, Sujit; Senevirathne, Chamara; Garre, Satish; Pflum, Mary Kay H.

2012-01-01

245

ATP binding to a multisubunit enzyme: statistical thermodynamics analysis  

E-print Network

Due to inter-subunit communication, multisubunit enzymes usually hydrolyze ATP in a concerted fashion. However, so far the principle of this process remains poorly understood. In this study, from the viewpoint of statistical thermodynamics, a simple model is presented. In this model, we assume that the binding of ATP will change the potential of the corresponding enzyme subunit, and the degree of this change depends on the state of its adjacent subunits. The probability of enzyme in a given state satisfies the Boltzmann's distribution. Although it looks much simple, this model can fit the recent experimental data of chaperonin TRiC/CCT well. From this model, the dominant state of TRiC/CCT can be obtained. This study provided a new way to understand biophysical processes by statistical thermodynamics analysis.

Yunxin Zhang

2012-03-22

246

Students' interdisciplinary reasoning about "high-energy bonds" and ATP  

NASA Astrophysics Data System (ADS)

Students' sometimes contradictory ideas about ATP (adenosine triphosphate) and the nature of chemical bonds have been studied in the biology and chemistry education literatures, but these topics are rarely part of the introductory physics curriculum. We present qualitative data from an introductory physics course for undergraduate biology majors that seeks to build greater interdisciplinary coherence and therefore includes these topics. In these data, students grapple with the apparent contradiction between the energy released when the phosphate bond in ATP is broken and the idea that an energy input is required to break a bond. We see that students' perceptions of how each scientific discipline bounds the system of interest can influence how they justify their reasoning about a topic that crosses disciplines. This has consequences for a vision of interdisciplinary education that respects disciplinary perspectives while bringing them into interaction in ways that demonstrate consistency amongst the perspectives.

Dreyfus, Benjamin W.; Geller, Benjamin D.; Sawtelle, Vashti; Svoboda, Julia; Turpen, Chandra; Redish, Edward F.

2013-01-01

247

Statistical Mechanics Analysis of ATP Binding to a Multisubunit Enzyme  

NASA Astrophysics Data System (ADS)

Due to inter-subunit communication, multisubunit enzymes usually hydrolyze ATP in a concerted fashion. However, so far the principle of this process remains poorly understood. In this study, from the viewpoint of statistical mechanics, a simple model is presented. In this model, we assume that the binding of ATP will change the potential of the corresponding enzyme subunit, and the degree of this change depends on the state of its adjacent subunits. The probability of enzyme in a given state satisfies the Boltzmann's distribution. Although it looks much simple, this model can fit the recent experimental data of chaperonin TRiC/CCT well. From this model, the dominant state of TRiC/CCT can be obtained. This study provide a new way to understand biophysical processe by statistical mechanics analysis.

Zhang, Yun-Xin

2014-10-01

248

Ionotropic ATP receptors in neuronal-glial communication.  

PubMed

In the central nervous system ATP is released from both neurones and astroglial cells acting as a homo- and heterocellular neurotransmitter. Glial cells express numerous purinoceptors of both ionotropic (P2X) and metabotropic (P2Y) varieties. Astroglial P2X receptors can be activated by ongoing synaptic transmission and can mediate fast local signalling through elevation in cytoplasmic Ca(2+) and Na(+) concentrations. These ionic signals can be translated into various physiological messages by numerous pathways, including release of gliotransmitters, metabolic support of neurones and regulation of activity of postsynaptic glutamate and GABA receptors. Ionotropic purinoceptors represent a novel pathway of glia-driven modulation of synaptic signalling that involves the release of ATP from neurones and astrocytes followed by activation of P2X receptors which can regulate synaptic activity by variety of mechanisms expressed in both neuronal and glial compartments. PMID:21320623

Lalo, Ulyana; Verkhratsky, Alexei; Pankratov, Yuri

2011-04-01

249

ATP-dependent proteases that also chaperone protein biogenesis  

Microsoft Academic Search

The ATP-dependent proteases Clp and FtsH from bacteria, as well as mitochondrial homologs of FtsH and Lon from yeast, may act as chaperones; they mediate not only proteolysis, but also the insertion of proteins into membranes and the disassembly or oligomerization of protein complexes. The coordination of such processes with selective proteolysis may function in the quality control of protein

Carolyn K. Suzuki; Martijn Rep; Jan Maarten van Dijl; Kitaru Suda; Leslie A. Grivell; Gottfried Schatz

1997-01-01

250

Hypothermic Oscillating Liver Perfusion Stimulates ATP Synthesis prior to Transplantation  

Microsoft Academic Search

Background.ATP and glycogen depletion often have been demonstrated during cold storage of the liver prior to transplantation. Suppression of events that lead to metabolic depression and to lipid peroxidation could contribute to improvement of liver preservation. A new method of liver preservation for transplantation is therefore suggested, an oscillating oxygenated hypothermic liver perfusion.Methods.Biochemical analysis of liver tissue samples and perfusate

P. Dutkowski; B. Odermatt; T. Heinrich; S. Schönfeld; M. Watzka; V. Winkelbach; M. Krysiak; T. Junginger

1998-01-01

251

Extracellular ATP signaling in equine digital blood vessels.  

PubMed

The functional distribution of ATP-activated P2 receptors is well characterized for many blood vessels, but not in the equine digital vasculature, which is a superficial vascular bed that displays thermoregulatory functions and has been implicated in ischemia-reperfusion injuries of the hoof. Isolated equine digital arteries (EDA) and veins (EDV) were submitted to isometric tension studies, whereby electric field stimulation (EFS) and concentration-response curves to exogenously applied agonists were constructed under low tone conditions. Additionally, immunofluorescent localization of P2X and P2Y receptor subtypes was performed. EFS-induced constriction was abolished by tetrodotoxin (1 ?M, n=4). Endothelium denudation did not modify the EFS-induced constriction (n=3). The EFS-induced constriction in EDA was inhibited by phentolamine (67.7±1.8%, n=6; 10 ?M), and by the non-selective P2 receptor antagonist suramin (46.2±1.3%, n=6; 10 ?M). EFS-induced constriction in EDV was reduced by suramin (48.2±2.4%, n=6; 10 ?M), the P2 receptor antagonist pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (58.3±4.5%, n=6; 10 ?M), and phentolamine (23.2±2.5%, n=6; 10 ?M). Exogenous methoxamine and ATP mimicked EFS-induced constriction in EDA and EDV. Immunostaining for P2X1, P2X2 and P2X3, and, for P2X1 and P2X7 receptor subunits were observed in EDA and EDV smooth muscle and adventitia, respectively. ATP and noradrenaline are co-transmitters in sympathetic nerves supplying the equine digital vasculature, noradrenaline being the dominant agonist in EDA, and ATP in EDV. In conclusion, P2X receptors mediate vasoconstriction in EDA and EDV, although different P2X subunits are involved in these vessels. The physiological significance of this finding in relation to thermoregulatory functions and equine laminitis is discussed. PMID:23370179

Zerpa, Hector; Crawford, Carol; Knight, Gillian E; Fordham, Alice F; Janska, Silvia E; Peppiatt-Wildman, Claire M; Elliott, Jonathan; Burnstock, Geoffrey; Wildman, Scott S

2013-02-28

252

ATP as a mediator of mammalian central CO2 chemoreception  

PubMed Central

A role for P2 purinoceptors in the chemosensory response of respiratory neurones localised in the ventrolateral medulla to changes in arterial CO2 levels was investigated in the anaesthetised rat. Extracellular recordings were made from different classes of respiratory neurone and the effects of P2 receptor blockade on CO2-evoked changes in activity investigated. Increasing inspired CO2 excited 85 % of inspiratory neurones in the pre-Bötzinger complex. In all cases, CO2-evoked excitation was blocked by ionophoretic application of the P2receptor antagonists suramin (0·02 M) and pyridoxal-phosphate-6-azophenyl-2?,4?-disulphonic acid (PPADS; 100 ?M), but not the adenosine receptor antagonist 8-phenyltheophylline (8-PT; 100 ?M). Suramin and PPADS often reduced ongoing activity, and blocked the excitatory effects of ATP. Inspiratory neurones were also excited by the P2X receptor agonist ??-methyleneATP, suggesting a specific role for P2X receptors. Sixty-six per cent of pre-inspiratory neurones were also excited by CO2. This effect was reduced or abolished by prior application of P2 receptor antagonists. Although post-inspiratory and expiratory neurones were excited by increasing levels of CO2, and also by ionophoretically applied ATP, the CO2-evoked effects were unaffected by P2 receptor blockade. We suggest that ATP, possibly acting via P2X purinoceptors localised within the ventral respiratory group, is involved in central chemoreception. Specifically, these distinctive CO2-P2X-mediated actions were observed only in inspiratory neurones (incrementing inspiratory neurones and pre-inspiratory neurones), which appear to have purinoceptors with pH sensitivity that can account for the actions of CO2 in modifying ventilatory activity. PMID:10699087

Thomas, T; Spyer, K M

2000-01-01

253

Allosteric regulation of focal adhesion kinase by PIP? and ATP.  

PubMed

Focal adhesion kinase (FAK) is a nonreceptor tyrosine kinase that regulates cell signaling, proliferation, migration, and development. A major mechanism of regulation of FAK activity is an intramolecular autoinhibitory interaction between two of its domains--the catalytic and FERM domains. Upon cell adhesion to the extracellular matrix, FAK is being translocated toward focal adhesion sites and activated. Interactions of FAK with phosphoinositide phosphatidylinsositol-4,5-bis-phosphate (PIP?) are required to activate FAK. However, the molecular mechanism of the activation remains poorly understood. Recent fluorescence resonance energy transfer experiments revealed a closure of the FERM-kinase interface upon ATP binding, which is reversed upon additional binding of PIP?. Here, we addressed the allosteric regulation of FAK by performing all-atom molecular-dynamics simulations of a FAK fragment containing the catalytic and FERM domains, and comparing the dynamics in the absence or presence of ATP and PIP?. As a major conformational change, we observe a closing and opening motion upon ATP and additional PIP? binding, respectively, in good agreement with the fluorescence resonance energy transfer experiments. To reveal how the binding of the regulatory PIP? to the FERM F2 lobe is transduced to the very distant F1/N-lobe interface, we employed force distribution analysis. We identified a network of mainly charged residue-residue interactions spanning from the PIP? binding site to the distant interface between the kinase and FERM domains, comprising candidate residues for mutagenesis to validate the predicted mechanism of FAK activation. PMID:25650936

Zhou, Jing; Bronowska, Agnieszka; Le Coq, Johanne; Lietha, Daniel; Gräter, Frauke

2015-02-01

254

Hemolysis is a primary ATP-release mechanism in human erythrocytes  

PubMed Central

The hypothesis that regulated ATP release from red blood cells (RBCs) contributes to nitric oxide-dependent control of local blood flow has sparked much interest in underlying release mechanisms. Several stimuli, including shear stress and hypoxia, have been found to induce significant RBC ATP release attributed to activation of ATP-conducting channels. In the present study, we first evaluated different experimental approaches investigating stimulated RBC ATP release and quantifying hemolysis. We then measured ATP and free hemoglobin in each and every RBC supernatant sample to directly assess the contribution of hemolysis to ATP release. Hypotonic shock, shear stress, and hypoxia, but not cyclic adenosine monophosphate agonists, significantly enhanced ATP release. It tightly correlated, however, with free hemoglobin in RBC supernatants, indicating that lysis was responsible for most, if not all, ATP release. Luminescence ATP imaging combined with simultaneous infrared cell imaging showed that ATP was released exclusively from lysing cells with no contribution from intact cells. In summary, with all stimuli tested, we found no evidence of regulated ATP release from intact RBCs other than by cell lysis. Such a release mechanism might be physiologically relevant in vivo, eg, during exercise and hypoxia where intravascular hemolysis, predominantly of senescent cells, is augmented. PMID:25097178

Sikora, Jacek; Orlov, Sergei N.; Furuya, Kishio

2014-01-01

255

ATP-responsive DNA-graphene hybrid nanoaggregates for anticancer drug delivery.  

PubMed

Stimuli-triggered drug delivery systems are primarily focused on the applications of the tumor microenvironmental or cellular physiological cues to enhance the release of drugs at the target site. In this study, we applied adenosine-5'-triphosphate (ATP), the primary "energy molecule", as a trigger for enhanced release of preloaded drugs responding to the intracellular ATP concentration that is significantly higher than the extracellular level. A new ATP-responsive anticancer drug delivery strategy utilizing DNA-graphene crosslinked hybrid nanoaggregates as carriers was developed for controlled release of doxorubicin (DOX), which consists of graphene oxide (GO), two single-stranded DNA (ssDNA, denoted as DNA1 and DNA2) and ATP aptamer. The single-stranded DNA1 and DNA2 together with the ATP aptamer serve as the linkers upon hybridization for controlled assembly of the DNA-GO nanoaggregates, which effectively inhibited the release of DOX from the GO nanosheets. In the presence of ATP, the responsive formation of the ATP/ATP aptamer complex causes the dissociation of the aggregates, which promoted the release of DOX in the environment with a high ATP concentration such as cytosol compared with that in the ATP-deficient extracellular fluid. This supports the development of a novel ATP-responsive platform for targeted on-demand delivery of anticancer drugs inside specific cells. PMID:25736497

Mo, Ran; Jiang, Tianyue; Sun, Wujin; Gu, Zhen

2015-05-01

256

Hemolysis is a primary ATP-release mechanism in human erythrocytes.  

PubMed

The hypothesis that regulated ATP release from red blood cells (RBCs) contributes to nitric oxide-dependent control of local blood flow has sparked much interest in underlying release mechanisms. Several stimuli, including shear stress and hypoxia, have been found to induce significant RBC ATP release attributed to activation of ATP-conducting channels. In the present study, we first evaluated different experimental approaches investigating stimulated RBC ATP release and quantifying hemolysis. We then measured ATP and free hemoglobin in each and every RBC supernatant sample to directly assess the contribution of hemolysis to ATP release. Hypotonic shock, shear stress, and hypoxia, but not cyclic adenosine monophosphate agonists, significantly enhanced ATP release. It tightly correlated, however, with free hemoglobin in RBC supernatants, indicating that lysis was responsible for most, if not all, ATP release. Luminescence ATP imaging combined with simultaneous infrared cell imaging showed that ATP was released exclusively from lysing cells with no contribution from intact cells. In summary, with all stimuli tested, we found no evidence of regulated ATP release from intact RBCs other than by cell lysis. Such a release mechanism might be physiologically relevant in vivo, eg, during exercise and hypoxia where intravascular hemolysis, predominantly of senescent cells, is augmented. PMID:25097178

Sikora, Jacek; Orlov, Sergei N; Furuya, Kishio; Grygorczyk, Ryszard

2014-09-25

257

Spike-independent release of ATP from Xenopus spinal neurons evoked by activation of glutamate receptors  

PubMed Central

As the release of ATP from neurons has only been directly studied in a few cases, we have used patch sniffing to examine ATP release from Xenopus spinal neurons. ATP release was detected following intracellular current injection to evoke spikes. However, spiking was not essential as both glutamate and NMDA could evoke release of ATP in the presence of TTX. Neither acetylcholine nor high K+ was effective at inducing ATP release in the presence of TTX. Although Cd2+ blocked glutamate-evoked release of ATP suggesting a dependence on Ca2+ entry, neither ?-conotoxin-GVIA nor nifedipine prevented ATP release. N-type and L-type channels are thus not essential for glutamate-evoked ATP release. That glutamate receptors can elicit release in the absence of spiking suggests a close physical relationship between these receptors, the Ca2+ channels and release sites. As the dependence of ATP release on the influx of Ca2+ through Ca2+ channel subtypes differs from that of synaptic transmitter release, ATP may be released from sites that are distinct from those of the principal transmitter. In addition to its role as a fast transmitter, ATP may thus be released as a consequence of the activation of excitatory glutamatergic synapses and act to signal information about activity patterns in the nervous system. PMID:11986374

Brown, Paul; Dale, Nicholas

2002-01-01

258

Blockade of adenosine receptors unmasks a stimulatory effect of ATP on cardiac contractility.  

PubMed Central

1. The effects of ATP, alpha,beta-methylene ATP and beta,gamma-methylene ATP on the contractile tension of guinea-pig isolated left atria were evaluated. 2. ATP (1-100 microM) produced a concentration-dependent negative inotropic effect; this response was converted to a positive inotropic effect in the presence of the antagonist of adenosine A1 receptors, 1,3-dipropyl-8-cyclopentylxanthine (DPCPX; 0.1 microM), and in the presence of 8-phenyltheophylline (10 microM), an antagonist of A1 and A2 receptors. 3. The positive inotropic effect of ATP was antagonized by the P2 receptor antagonist, suramin (500 microM). Reactive blue 2 (30-500 microM), a putative P2y receptor antagonist, concentration-dependently reduced and finally abolished the effect of ATP. 4. In the presence of 8-phenyltheophylline, the stable analogues of ATP, alpha,beta-methylene ATP and beta,gamma-methylene ATP (1-30 microM), produced a concentration-dependent increase in atrial contractility of a lesser degree than that induced by ATP. 5. The results suggest that when inhibitory adenosine receptors are blocked, ATP produces a positive inotropic effect, probably mediated by P2y receptor stimulation. PMID:8401938

Mantelli, L.; Amerini, S.; Filippi, S.; Ledda, F.

1993-01-01

259

An intersubunit signaling network coordinates ATP hydrolysis by m-AAA proteases  

PubMed Central

Summary Ring-shaped AAA+ ATPases control a variety of cellular processes by substrate unfolding and remodeling of macromolecular structures. However, how ATP hydrolysis within AAA+ rings is regulated and coupled to mechanical work is poorly understood. Here, we demonstrate coordinated ATP hydrolysis within m-AAA protease ring complexes, conserved AAA+ machines in the inner membrane of mitochondria. ATP binding to one AAA subunit inhibits ATP hydrolysis by the neighboring subunit leading to coordinated rather than stochastic ATP hydrolysis within the AAA ring. Unbiased genetic screens define an intersubunit signaling pathway involving conserved AAA motifs and reveal an intimate coupling of ATPase activities to central AAA pore loops. Coordinated ATP hydrolysis between adjacent subunits is required for membrane dislocation of substrates but not for substrate processing. These findings provide new insight how AAA+ proteins convert energy derived from ATP hydrolysis into mechanical work. PMID:19748354

Augustin, Steffen; Gerdes, Florian; Lee, Sukyeong; Tsai, Francis T.F.; Langer, Thomas; Tatsuta, Takashi

2009-01-01

260

Toward a multiscale description of microvascular flow regulation: o(2)-dependent release of ATP from human erythrocytes and the distribution of ATP in capillary networks.  

PubMed

Integration of the numerous mechanisms that have been suggested to contribute to optimization of O(2) supply to meet O(2) need in skeletal muscle requires a systems biology approach which permits quantification of these physiological processes over a wide range of length scales. Here we describe two individual computational models based on in vivo and in vitro studies which, when incorporated into a single robust multiscale model, will provide information on the role of erythrocyte-released ATP in perfusion distribution in skeletal muscle under both physiological and pathophysiological conditions. Healthy human erythrocytes exposed to low O(2) tension release ATP via a well characterized signaling pathway requiring activation of the G-protein, Gi, and adenylyl cyclase leading to increases in cAMP. This cAMP then activates PKA and subsequently CFTR culminating in ATP release via pannexin 1. A critical control point in this pathway is the level of cAMP which is regulated by pathway-specific phosphodiesterases. Using time constants (~100?ms) that are consistent with measured erythrocyte ATP release, we have constructed a dynamic model of this pathway. The model predicts levels of ATP release consistent with measurements obtained over a wide range of hemoglobin O(2) saturations (sO(2)). The model further predicts how insulin, at concentrations found in pre-diabetes, enhances the activity of PDE3 and reduces intracellular cAMP levels leading to decreased low O(2)-induced ATP release from erythrocytes. The second model, which couples O(2) and ATP transport in capillary networks, shows how intravascular ATP and the resulting conducted vasodilation are affected by local sO(2), convection and ATP degradation. This model also predicts network-level effects of decreased ATP release resulting from elevated insulin levels. Taken together, these models lay the groundwork for investigating the systems biology of the regulation of microvascular perfusion distribution by erythrocyte-derived ATP. PMID:22934004

Goldman, Daniel; Fraser, Graham M; Ellis, Christopher G; Sprague, Randy S; Ellsworth, Mary L; Stephenson, Alan H

2012-01-01

261

Electrical currents associated with nucleotide transport by the reconstituted mitochondrial ADP/ATP carrier.  

PubMed Central

The electrophoretic export of ATP against the import of ADP in mitochondria bridges the intra- versus extramitochondrial ATP potential gap. Here we report that the electrical nature of the ADP/ATP exchange by the mitochondrial ADP/ATP carrier (AAC) can be directly studied by measuring the electrical currents via capacitive coupling of AAC-containing vesicles on a planar lipid membrane. The currents were induced by the rapid liberation of ATP or ADP with UV flash photolysis from caged nucleotides. Six different transport modes of the AAC were studied: heteroexchange with either ADP or ATP inside the vesicles, initiated by photolysis of caged ATP or ADP; homoexchange with ADPex/ADPin or ATPex/ATPin; and caged ADP or ATP with unloaded vesicles. The heteroexchange produced the largest currents with the longest duration in line with the electrical charge difference ATP4- versus ADP3-. Surprisingly, also in the homoexchange and with unloaded vesicles, small currents were measured with shorter duration. In all three modes with caged ATP, a negative charge moved into the vesicles and with caged ADP it moved out of the vesicles. All currents were completely inhibited by a mixture of the inhibitors of the AAC, carboxyatractyloside and hongkrekate, which proves that the currents are exclusively due to AAC function. The observed charge movements in the heteroexchange system agree with the prediction from transport studies in mitochondria and reconstituted vesicles. The unexpected charge movements in the homoexchange or unloaded systems are interpreted to reveal transmembrane rearrangements of charged sites in the AAC when occupied with ADP or ATP. The results also indicate that not only ATP4- but also ADP3- contribute, albeit in opposite direction, to the electrical nature of the ADP/ATP exchange, which is at variance with former conclusions from biochemical transport studies. These measurements open up new avenues of studying the electrical interactions of ADP and ATP with the AAC. Images Fig. 5 PMID:8570612

Brustovetsky, N; Becker, A; Klingenberg, M; Bamberg, E

1996-01-01

262

Protons, the thylakoid membrane, and the chloroplast ATP synthase.  

PubMed

According to the chemiosmotic theory, proton pumps and ATP synthases are coupled by lateral proton flow through aqueous phases. Three long-standing challenges to this concept, all of which have been loosely subsumed under 'localized coupling' in the literature, were examined in the light of experiments carried out with thylakoids: (1) Nearest neighbor interaction between pumps and ATP synthases. Considering the large distances between photosystem II and CFoCF1, in stacked thylakoids this is a priori absent. (2) Enhanced proton diffusion along the surface of the membrane. This could not be substantiated for the outer side of the thylakoid membrane. Even for the interface between pure lipid and water, two laboratories have reported the absence of enhanced diffusion. (3) Localized proton ducts in the membrane. Intramembrane domains that can transiently trap protons do exist in thylakoid membranes, but because of their limited storage capacity for protons, they probably do not matter for photophosphorylation under continuous light. Seemingly in favor of localized proton ducts is the failure of a supposedly permeant buffer to enhance the onset lag of photophosphorylation. However, it was found that failure of some buffers and the ability of others in this respect were correlated with their failure/ability to quench pH transients in the thylakoid lumen, as predicted by the chemiosmotic theory. It was shown that the chemiosmotic concept is a fair approximation, even for narrow aqueous phases, as in stacked thylakoids. These are approximately isopotential, and protons are taken in by the ATP synthase straight from the lumen. The molecular mechanism by which F0F1 ATPases couple proton flow to ATP synthesis is still unknown. The threefold structural symmetry of the headpiece that, probably, finds a corollary in the channel portion of these enzymes appeals to the common wisdom that structural symmetry causes functional symmetry. "Rotation catalysis" has been proposed. It is of heuristic value to visualize CFoCF1 as a mechanical coupling device. Its maximum turnover number ranges up to 400 s-1 for ATP and 1200 s-1 for protons. At about 200 mV electric driving force this implied a conductance of about 1 fS. Its channel portion (CFo), however, has revealed a very large protonic conductance of 1 pS (three orders of magnitude greater than the protonic conductance of gramicidin around neutral pH). (6) The sight and smell of food increased LH serotonin release; this effect was detectable when local fluoxetine was used to block serotonin reuptake.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:2483874

Junge, W

1989-01-01

263

Cervical anterior transpedicular screw fixation (ATPS)—Part II. Accuracy of manual insertion and pull-out strength of ATPS  

Microsoft Academic Search

Reconstruction after multilevel decompression of the cervical spine, especially in the weakened osteoporotic, neoplastic or\\u000a infectious spine often requires circumferential stabilization and fusion. To avoid the additional posterior surgery in these\\u000a cases while increasing rigidity of anterior-only screw-plate constructs, the authors introduce the concept of anterior transpedicular\\u000a screw (ATPS) fixation. We demonstrated its morphological feasibility as well as its indications

Heiko Koller; Frank Acosta; Mark Tauber; Michael Fox; Hudelmaier Martin; Rosmarie Forstner; Peter Augat; Rainer Penzkofer; Christian Pirich; H. Kässmann; Herbert Resch; Wolfgang Hitzl

2008-01-01

264

New complexes of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) ions with morin.  

PubMed

New solid complex compounds of La(III), Ce(III), Pr(III), Nd(III), Sm(III), Eu(III) and Gd(III) ions with morin were synthesized. The molecular formula of the complexes is Ln(C(15)H(9)O(7))(3).nH(2)O, where Ln is the cation of lanthanide and n=6 for La(III), Sm(III), Gd(III) or n=8 for Ce(III), Pr(III), Nd(III) and Eu(III). Thermogravimetric studies and the values of dehydration enthalpy indicate that water occurring in the compounds is not present in the inner coordination sphere of the complex. The structure of the complexes was determined on the basis of UV-visible, IR, MS, (1)H NMR and (13)C NMR analyses. It was found that in binding the lanthanide ions the following groups of morin take part: 3OH and 4CO in the case of complexes of La, Pr, Nd, Sm and Eu, or 5OH and 4CO in the case of complexes of Ce and Gd. The complexes are five- and six-membered chelate compounds. PMID:17368778

Wo?nicka, Elzbieta; Kopacz, Maria; Umbreit, Micha?; K?os, Jolanta

2007-05-01

265

Synthesis of bisphosphonate derivatives of ATP by T4 DNA ligase, ubiquitin activating enzyme (E1) and other ligases.  

PubMed

T4 DNA ligase and the ubiquitin activating enzyme (E1), catalyze the synthesis of ATP beta,gamma-bisphosphonate derivatives. Concerning T4 DNA ligase: (i) etidronate (pC(OH)(CH(3))p) displaced the AMP moiety of the complex E-AMP in a concentration dependent manner; (ii) the K(m) values and the rate of synthesis k(cat) (s(-1)), determined for the following compounds were, respectively: etidronate, 0.73+/-0.09 mM and (70+/-10)x10(-3) s(-1); clodronate (pCCl(2)p), 0.08+/-0.01 mM and (4.1+/-0.3)x10(-3) s(-1); methylenebisphosphonate (pCH(2)p), 0.024+/-0.001 mM and (0.6+/-0.1)x10(-3) s(-1); tripolyphosphate (P(3)) (in the synthesis of adenosine 5'-tetraphosphate, p(4)A), 1.30+/-0.30 mM and (6.2+/-1.1)x10(-3) s(-1); (iii) in the presence of GTP and ATP, inhibition of the synthesis of Ap(4)G was observed with clodronate but not with pamidronate (pC(OH)(CH(2)-CH(2)-NH(3))p). Concerning the ubiquitin activating enzyme (E1): methylenebisphosphonate was the only bisphosphonate, out of the ones tested, that served as substrate for the synthesis of an ATP derivative (K(m)=0.36+/-0.09 mM and k(cat)=0.15+/-0.02 s(-1)). None of the above bisphosphonates were substrates of the reaction catalyzed by luciferase or by acyl-CoA synthetase. The ability of acetyl-CoA synthetase to use methylenebisphosphonate as substrate depended on the commercial source of the enzyme. In our view this report widens our knowledge of the enzymes able to metabolize bisphosphonates, a therapeutic tool widely used in the treatment of osteoporosis. PMID:18378215

Günther Sillero, María A; de Diego, Anabel; Pérez-Zúñiga, Francisco J; Sillero, Antonio

2008-05-15

266

Vps4 stimulatory element of the cofactor Vta1 contacts the ATPase Vps4 ?7 and ?9 to stimulate ATP hydrolysis.  

PubMed

The endosomal sorting complexes required for transport (ESCRTs) function in a variety of membrane remodeling processes including multivesicular body sorting, abscission during cytokinesis, budding of enveloped viruses, and repair of the plasma membrane. Vps4 ATPase activity modulates ESCRT function and is itself modulated by its cofactor Vta1 and its substrate ESCRT-III. The carboxyl-terminal Vta1/SBP-1/Lip5 (VSL) domain of Vta1 binds to the Vps4 ?-domain to promote Vps4 oligomerization-dependent ATP hydrolysis. Additionally, the Vps4 stimulatory element (VSE) of Vta1 contributes to enhancing Vps4 oligomer ATP hydrolysis. The VSE is also required for Vta1-dependent stimulation of Vps4 by ESCRT-III subunits. However, the manner by which the Vta1 VSE contributes to Vps4 activation is unknown. Existing structural data were used to generate a model of the Vta1 VSE in complex with Vps4. This model implicated residues within the small ATPase associated with various activities (AAA) domain, specifically ?-helices 7 and 9, as relevant contact sites. Rational generation of Vps4 mutants defective for VSE-mediated stimulation, as well as intergenic compensatory mutations, support the validity of this model. These findings have uncovered the Vps4 surface responsible for coordinating ESCRT-III-stimulated Vta1 input during ESCRT function and identified a novel mechanism of Vps4 stimulation. PMID:25164817

Davies, Brian A; Norgan, Andrew P; Payne, Johanna A; Schulz, Mary E; Nichols, Micah D; Tan, Jason A; Xu, Zhaohui; Katzmann, David J

2014-10-10

267

ATP Utilization by Yeast Replication Factor C IV. RFC ATP-BINDING MUTANTS SHOW DEFECTS IN DNA REPLICATION, DNA REPAIR, AND CHECKPOINT  

E-print Network

the energy of ATP hydrolysis. Four of the five RFC genes have consensus ATP-binding motifs. To determine mu- tations in all RFC genes tested permitted cell growth, although poor growth was observed for rfc2. Most double mu- tants combining mutations in two RFC genes were invi- able. Except for the rfc1-K359R

Burgers, Peter M.

268

Nutrient-starved, non-replicating Mycobacterium tuberculosis requires respiration, ATP synthase and isocitrate lyase for maintenance of ATP homeostasis and viability.  

PubMed

The ability of Mycobacterium tuberculosis to persist in its human host despite extensive chemotherapy is thought to be based on subpopulations of non-replicating phenotypically drug-resistant bacilli. To study the non-growing pathogen, culture models that generate quiescent organisms by either oxygen depletion in nutrient-rich medium (Wayne model) or nutrient deprivation in oxygen-rich medium (Loebel model) have been developed. In contrast to the energy metabolism of Wayne bacilli, little is known about Loebel bacilli. Here we analysed M. tuberculosis under nutrient-starvation conditions. Upon shifting to the non-replicating state the pathogen maintained a fivefold reduced but constant intracellular ATP level. Chemical probing of the F(0)F(1) ATP synthase demonstrated the importance of this enzyme for ATP homeostasis and viability of the nutrient-starved organism. Surprisingly, the specific ATP synthase inhibitor TMC207 did not affect viability and only moderately reduced the intracellular ATP level of nutrient-starved organisms. Depletion of oxygen killed Loebel bacilli, whereas death was prevented by nitrate, suggesting that respiration and an exogenous electron acceptor are required for maintaining viability. Nutrient-starved bacilli lacking the glyoxylate shunt enzyme isocitrate lyase failed to reduce their intracellular ATP level and died, thus establishing a link between ATP control and intermediary metabolism. We conclude that reduction of the ATP level might be an important step in the adaptation of M. tuberculosis to non-growing survival. PMID:19797356

Gengenbacher, Martin; Rao, Srinivasa P S; Pethe, Kevin; Dick, Thomas

2010-01-01

269

Definitions of dwelling  

E-print Network

Home is an elusive concept. In one manner it is highly specific and individual in its definition, and in other aspects it is ubiquitous, present in our every act. In this thesis I explore several possible definitions of ...

Olgyay, Victor W. (Victor Wayne)

1986-01-01

270

Bifidobacterium lactis DSM 10140: Identification of the atp (atpBEFHAGDC) Operon and Analysis of Its Genetic Structure, Characteristics, and Phylogeny  

PubMed Central

The atp operon is highly conserved among eubacteria, and it has been considered a molecular marker as an alternative to the 16S rRNA gene. PCR primers were designed from the consensus sequences of the atpD gene to amplify partial atpD sequences from 12 Bifidobacterium species and nine Lactobacillus species. All PCR products were sequenced and aligned with other atpD sequences retrieved from public databases. Genes encoding the subunits of the F1F0-ATPase of Bifidobacterium lactis DSM 10140 (atpBEFHAGDC) were cloned and sequenced. The deduced amino acid sequences of these subunits showed significant homology with the sequences of other organisms. We identified specific sequence signatures for the genus Bifidobacterium and for the closely related taxa Bifidobacterium lactis and Bifidobacterium animalis and Lactobacillus gasseri and Lactobacillus johnsonii, which could provide an alternative to current methods for identification of lactic acid bacterial species. Northern blot analysis showed that there was a transcript at approximately 7.3 kb, which corresponded to the size of the atp operon, and a transcript at 4.5 kb, which corresponded to the atpC, atpD, atpG, and atpA genes. The transcription initiation sites of these two mRNAs were mapped by primer extension, and the results revealed no consensus promoter sequences. Phylogenetic analysis of the atpD genes demonstrated that the Lactobacillus atpD gene clustered with the genera Listeria, Lactococcus, Streptococcus, and Enterococcus and that the higher G+C content and highly biased codon usage with respect to the genome average support the hypothesis that there was probably horizontal gene transfer. The acid inducibility of the atp operon of B. lactis DSM 10140 was verified by slot blot hybridization by using RNA isolated from acid-treated cultures of B. lactis DSM 10140. The rapid increase in the level of atp operon transcripts upon exposure to low pH suggested that the ATPase complex of B. lactis DSM 10140 was regulated at the level of transcription and not at the enzyme assembly step. PMID:15128574

Ventura, Marco; Canchaya, Carlos; van Sinderen, Douwe; Fitzgerald, Gerald F.; Zink, Ralf

2004-01-01

271

Single point mutations in ATP synthase compensate for mitochondrial genome loss in trypanosomes.  

PubMed

Viability of the tsetse fly-transmitted African trypanosome Trypanosoma brucei depends on maintenance and expression of its kinetoplast (kDNA), the mitochondrial genome of this parasite and a putative target for veterinary and human antitrypanosomatid drugs. However, the closely related animal pathogens T. evansi and T. equiperdum are transmitted independently of tsetse flies and survive without a functional kinetoplast for reasons that have remained unclear. Here, we provide definitive evidence that single amino acid changes in the nuclearly encoded F1FO-ATPase subunit ? can compensate for complete physical loss of kDNA in these parasites. Our results provide insight into the molecular mechanism of compensation for kDNA loss by showing FO-independent generation of the mitochondrial membrane potential with increased dependence on the ADP/ATP carrier. Our findings also suggest that, in the pathogenic bloodstream stage of T. brucei, the huge and energetically demanding apparatus required for kDNA maintenance and expression serves the production of a single F1FO-ATPase subunit. These results have important implications for drug discovery and our understanding of the evolution of these parasites. PMID:23959897

Dean, Samuel; Gould, Matthew K; Dewar, Caroline E; Schnaufer, Achim C

2013-09-01

272

Single point mutations in ATP synthase compensate for mitochondrial genome loss in trypanosomes  

PubMed Central

Viability of the tsetse fly-transmitted African trypanosome Trypanosoma brucei depends on maintenance and expression of its kinetoplast (kDNA), the mitochondrial genome of this parasite and a putative target for veterinary and human antitrypanosomatid drugs. However, the closely related animal pathogens T. evansi and T. equiperdum are transmitted independently of tsetse flies and survive without a functional kinetoplast for reasons that have remained unclear. Here, we provide definitive evidence that single amino acid changes in the nuclearly encoded F1FO–ATPase subunit ? can compensate for complete physical loss of kDNA in these parasites. Our results provide insight into the molecular mechanism of compensation for kDNA loss by showing FO-independent generation of the mitochondrial membrane potential with increased dependence on the ADP/ATP carrier. Our findings also suggest that, in the pathogenic bloodstream stage of T. brucei, the huge and energetically demanding apparatus required for kDNA maintenance and expression serves the production of a single F1FO–ATPase subunit. These results have important implications for drug discovery and our understanding of the evolution of these parasites. PMID:23959897

Dean, Samuel; Gould, Matthew K.; Dewar, Caroline E.; Schnaufer, Achim C.

2013-01-01

273

A definition of dyslexia  

Microsoft Academic Search

This paper elaborates on the components of a working definition of developmental dyslexia. It follows the general format of\\u000a a paper by Lyon published in Annals of Dyslexia in 1995, which elaborated on a working definition proposed in 1994 (Lyon,\\u000a 1995). The current definition agreed on by the work group updates and expands on the working definition from 1994.

G. Reid Lyon; Sally E. Shaywitz; Bennett A. Shaywitz

2003-01-01

274

Copper directs ATP7B to the apical domain of hepatic cells via basolateral endosomes.  

PubMed

Physiologic Cu levels regulate the intracellular location of the Cu ATPase ATP7B. Here, we determined the routes of Cu-directed trafficking of endogenous ATP7B in the polarized hepatic cell line WIF-B and in the liver in vivo. Copper (10?µm) caused ATP7B to exit the trans-Golgi network (TGN) in vesicles, which trafficked via large basolateral endosomes to the apical domain within 1?h. Although perturbants of luminal acidification had little effect on the TGN localization of ATP7B in low Cu, they blocked delivery to the apical membrane in elevated Cu. If the vesicular proton-pump inhibitor bafilomycin-A1 (Baf) was present with Cu, ATP7B still exited the TGN, but accumulated in large endosomes located near the coverslip, in the basolateral region. Baf washout restored ATP7B trafficking to the apical domain. If ATP7B was staged apically in high Cu, Baf addition promoted the accumulation of ATP7B in subapical endosomes, indicating a blockade of apical recycling, with concomitant loss of ATP7B at the apical membrane. The retrograde pathway to the TGN, induced by Cu removal, was far less affected by Baf than the anterograde (Cu-stimulated) case. Overall, loss of acidification-impaired Cu-regulated trafficking of ATP7B at two main sites: (i) sorting and exit from large basolateral endosomes and (ii) recycling via endosomes near the apical membrane. PMID:25243755

Nyasae, Lydia K; Schell, Michael J; Hubbard, Ann L

2014-12-01

275

Wound-induced ATP release and EGF receptor activation in epithelial cells  

PubMed Central

Summary We have shown previously that wounding of human corneal epithelial (HCE) cells resulted in epidermal growth factor receptor (EGFR) transactivation through ectodomain shedding of heparin-binding EGF-like growth factor (HB-EGF). However, the initial signal to trigger these signaling events in response to cell injury remains elusive. In the present study, we investigated the role of ATP released from the injured cells in EGFR transactivation in HCE cells as well as in BEAS 2B cells, a bronchial epithelial cell line. Wounding of epithelial monolayer resulted in the release of ATP into the culture medium. The wound-induced rapid activation of phosphatidylinositol-3-kinase (PI3K) and extracellular signal-regulated kinase (ERK) pathways in HCE cells was attenuated by eliminating extracellular ATP, ADP and adenosine. The nonhydrolyzable ATP analog ATP-?-S induced rapid and sustained EGFR activation that depended on HB-EGF shedding and ADAM (a disintegrin and metalloproteinase). Targeting pathways leading to HB-EGF shedding and EGFR activation attenuated ATP-?-S-enhanced closure of small scratch wounds. The purinoceptor antagonist reactive blue 2 decreased wound closure and attenuated ATP-?-S induced HB-EGF shedding. Taken together, our data suggest that ATP, released upon epithelial injury, acts as an early signal to trigger cell responses including an increase in HB-EGF shedding, subsequent EGFR transactivation and its downstream signaling, resulting in wound healing. PMID:17284517

Yin, Jia; Xu, Keping; Zhang, Jing; Kumar, Ashok; Yu, Fu-Shin X.

2007-01-01

276

How Reliable Are ATP Bioluminescence Meters in Assessing Decontamination of Environmental Surfaces in Healthcare Settings?  

PubMed Central

Background Meters based on adenosine triphosphate (ATP) bioluminescence measurements in relative light units (RLU) are often used to rapidly assess the level of cleanliness of environmental surfaces in healthcare and other settings. Can such ATP measurements be adversely affected by factors such as soil and cleaner-disinfectant chemistry? Objective This study tested a number of leading ATP meters for their sensitivity, linearity of the measurements, correlation of the readings to the actual microbial contamination, and the potential disinfectant chemicals’ interference in their readings. Methods First, solutions of pure ATP in various concentrations were used to construct a standard curve and determine linearity and sensitivity. Serial dilutions of a broth culture of Staphylococcus aureus, as a representative nosocomial pathogen, were then used to determine if a given meter’s ATP readings correlated with the actual CFUs. Next, various types of disinfectant chemistries were tested for their potential to interfere with the standard ATP readings. Results All four ATP meters tested herein demonstrated acceptable linearity and repeatability in their readings. However, there were significant differences in their sensitivity to detect the levels of viable microorganisms on experimentally contaminated surfaces. Further, most disinfectant chemistries tested here quenched the ATP readings variably in different ATP meters evaluated. Conclusions Apart from their limited sensitivity in detecting low levels of microbial contamination, the ATP meters tested were also prone to interference by different disinfectant chemistries. PMID:24940751

Omidbakhsh, Navid; Ahmadpour, Faraz; Kenny, Nicole

2014-01-01

277

Controlled rotation of the F1-ATPase reveals differential and continuous binding changes for ATP synthesis  

PubMed Central

F1-ATPase is an ATP-driven rotary molecular motor that synthesizes ATP when rotated in reverse. To elucidate the mechanism of ATP synthesis, we imaged binding and release of fluorescently labelled ADP and ATP while rotating the motor in either direction by magnets. Here we report the binding and release rates for each of the three catalytic sites for 360° of the rotary angle. We show that the rates do not significantly depend on the rotary direction, indicating ATP synthesis by direct reversal of the hydrolysis-driven rotation. ADP and ATP are discriminated in angle-dependent binding, but not in release. Phosphate blocks ATP binding at angles where ADP binding is essential for ATP synthesis. In synthesis rotation, the affinity for ADP increases by >104, followed by a shift to high ATP affinity, and finally the affinity for ATP decreases by >104. All these angular changes are gradual, implicating tight coupling between the rotor angle and site affinities. PMID:22929779

Adachi, Kengo; Oiwa, Kazuhiro; Yoshida, Masasuke; Nishizaka, Takayuki; Kinosita, Kazuhiko

2012-01-01

278

Reciprocating-flow ATP amplification system for increasing the number of amplification cycles.  

PubMed

We constructed a novel ATP amplification reactor using a reciprocating-flow system to increase the number of ATP amplification cycles without an increase in backpressure. We previously reported a continuous-flow ATP amplification system that effectively and quantitatively amplified ATP and increased the sensitivity of a quantitative bioluminescence assay. However, it was difficult to increase the number of amplification cycles due to backpressure in the system. Because addition of immobilized adenylate kinase (ADK) and pyruvate kinase (PK) columns increased backpressure, the maximum number of ATP amplification cycles within column durability was only 4. In this study, ATP amplification was performed using a reciprocating-flow system, and 10 cycles of ATP amplification could be achieved without an increase in backpressure. As a result, ATP was amplified more than 100-fold after 10 cycles of reciprocating flow. The gradient of ATP amplification was approximately 1.76(N). The backpressure on the columns was 0.03 MPa in 1-10 ATP amplification cycles, and no increases in backpressure were observed. PMID:19699705

Satoh, Tetsuya; Tsuruta, Kosuke; Shinoda, Yasuharu; Hirota, Ryuichi; Noda, Kenichi; Kuroda, Akio; Murakami, Yuji

2009-12-15

279

Modeling the effects of hypoxia on ATP turnover in exercising muscle  

NASA Technical Reports Server (NTRS)

Most models of metabolic control concentrate on the regulation of ATP production and largely ignore the regulation of ATP demand. We describe a model, based on the results of Hogan et al. (J. Appl. Physiol. 73: 728-736, 1992), that incorporates the effects of ATP demand. The model is developed from the premise that a unique set of intracellular conditions can be measured at each level of ATP turnover and that this relationship is best described by energetic state. Current concepts suggest that cells are capable of maintaining oxygen consumption in the face of declines in the concentration of oxygen through compensatory changes in cellular metabolites. We show that these compensatory changes can cause significant declines in ATP demand and result in a decline in oxygen consumption and ATP turnover. Furthermore we find that hypoxia does not directly affect the rate of anaerobic ATP synthesis and associated lactate production. Rather, lactate production appears to be related to energetic state, whatever the PO2. The model is used to describe the interaction between ATP demand and ATP supply in determining final ATP turnover.

Arthur, P. G.; Hogan, M. C.; Bebout, D. E.; Wagner, P. D.; Hochachka, P. W.

1992-01-01

280

ATP Antagonizes Thrombin-Induced Signal Transduction through 12(S)-HETE and cAMP  

PubMed Central

In this study we have investigated the role of extracellular ATP on thrombin induced-platelet aggregation (TIPA) in washed human platelets. ATP inhibited TIPA in a dose-dependent manner and this inhibition was abolished by apyrase but not by adenosine deaminase (ADA) and it was reversed by extracellular magnesium. Antagonists of P2Y1 and P2Y12 receptors had no effect on this inhibition suggesting that a P2X receptor controlled ATP-mediated TIPA inhibition. ATP also blocked inositol phosphates (IP1, IP2, IP3) generation and [Ca2+]i mobilization induced by thrombin. Thrombin reduced cAMP levels which were restored in the presence of ATP. SQ-22536, an adenylate cyclase (AC) inhibitor, partially reduced the inhibition exerted by ATP on TIPA. 12-lipoxygenase (12-LO) inhibitors, nordihidroguaretic acid (NDGA) and 15(S)-hydroxy-5,8,11,13-eicosatetraenoic acid (15(S)-HETE), strongly prevented ATP-mediated TIPA inhibition. Additionally, ATP inhibited the increase of 12(S)-hydroxy-5,8,10,14-eicosatetraenoic acid (12(S)-HETE) induced by thrombin. Pretreatment with both SQ-22536 and NDGA almost completely abolished ATP-mediated TIPA inhibition. Our results describe for the first time that ATP implicates both AC and 12-LO pathways in the inhibition of human platelets aggregation in response to agonists. PMID:23826207

Burzaco, Jaione; Conde, Manuel; Parada, Luis A.; Zugaza, José L.; Dehaye, Jean-Paul; Marino, Aida

2013-01-01

281

Adenosine-5'-Triphosphate (ATP) Protects Mice against Bacterial Infection by Activation of the NLRP3 Inflammasome  

PubMed Central

It has been established that Adenosine-5'-triphosphate (ATP) can activate the NLRP3 inflammasome. However, the physiological effect of extracellular ATP on NLRP3 inflammasome activation has not yet been investigated. In the present study, we found that ATP was indeed released during bacterial infection. By using a murine peritonitis model, we also found that ATP promotes the fight against bacterial infection in mice. ATP induced the secretion of IL-1? and chemokines by murine bone marrow-derived macrophages in vitro. Furthermore, the intraperitoneal injection of ATP elevated the levels of IL-1? and chemokines in the mouse peritoneal lavage. Neutrophils were rapidly recruited to the peritoneum after ATP injection. In addition, the effects on cytokine and chemokine secretion and neutrophil recruitment were markedly attenuated by the pre-administration of the caspase-1 inhibitor Ac-YVAD-cho. Ac-YVAD-cho also significantly attenuated the protective effect of ATP against bacterial infection. In the present study, we demonstrated a protective role for ATP during bacterial infection and this effect was related to NLRP3 inflammasome activation. Together, these results suggest a role for ATP in initiating the immune response in hosts suffering from infections. PMID:23717478

Yan, Chao; Gao, Qian; Li, Sheng-An; Liu, Jie; Zhou, Kaifeng; Guo, Xiaolong; Lee, Wenhui; Zhang, Yun

2013-01-01

282

Comparative analysis of cytosolic and mitochondrial ATP synthesis in embryonic and postnatal hippocampal neuronal cultures  

PubMed Central

ATP in neurons is commonly believed to be synthesized mostly by mitochondria via oxidative phosphorylation. Neuronal mitochondria have been studied primarily in culture, i.e., in neurons isolated either from embryos or from neonatal pups. Although it is generally assumed that both embryonic and postnatal cultured neurons derive their ATP from mitochondrial oxidative phosphorylation, this has never been tested experimentally. We expressed the FRET-based ATP sensor AT1.03 in cultured hippocampal neurons isolated either from E17 to E18 rat embryos or from P1 to P2 rat pups and monitored [ATP]c simultaneously with mitochondrial membrane potential (??m; TMRM) and NAD(P)H autofluorescence. In embryonic neurons, transient glucose deprivation induced a near-complete decrease in [ATP]c, which was partially reversible and was accelerated by inhibition of glycolysis with 2-deoxyglucose. In the absence of glucose, pyruvate did not cause any significant increase in [ATP]c in 84% of embryonic neurons, and inhibition of mitochondrial ATP synthase with oligomycin failed to decrease [ATP]c. Moreover, ??m was significantly reduced by oligomycin, indicating that mitochondria acted as consumers rather than producers of ATP in embryonic neurons. In sharp contrast, in postnatal neurons pyruvate added during glucose deprivation significantly increased [ATP]c (by 54 ± 8%), whereas oligomycin induced a sharp decline in [ATP]c and increased ??m. These signs of oxidative phosphorylation were observed in all tested P1–P2 neurons. Measurement of ??m with the potential-sensitive probe JC-1 revealed that neuronal mitochondrial membrane potential was significantly reduced in embryonic cultures compared to the postnatal ones, possibly due to increased proton permeability of inner mitochondrial membrane. We conclude that, in embryonic, but not postnatal neuronal cultures, ATP synthesis is predominantly glycolytic and the oxidative phosphorylation-mediated synthesis of ATP by mitochondrial F1Fo-ATPase is insignificant. PMID:23335879

Surin, Alexander M.; Khiroug, Serguei; Gorbacheva, Lubov R.; Khodorov, Boris I.; Pinelis, Vsevolod G.; Khiroug, Leonard

2013-01-01

283

Reduced effectiveness of HMR 1098 in blocking cardiac sarcolemmal K(ATP) channels during metabolic stress.  

PubMed

ATP-sensitive K(+) (K(ATP)) channels are involved in ischemic cardioprotection induced by preconditioning (IPC), though the relative role of sarcolemmal (sK(ATP)) and mitochondrial (mitoK(ATP)) channels remains controversial. The sK(ATP)-selective sulphonylthiourea HMR 1098 has often been reported to be without effect on ischemic cardioprotection, suggesting minimal involvement of sK(ATP). Since some sulphonylureas show reduced potency under conditions of metabolic stress, we used patch clamp to assess the ability of HMR 1098 to block sK(ATP) currents of adult rat ventricular myocytes activated by metabolic inhibition (MI, NaCN+iodoacetate). In contrast to the prototype sulphonylurea glibenclamide, HMR 1098 (10 muM) was without effect on sK(ATP) currents, and also did not inhibit MI-induced action potential shortening. However, HMR 1098 blocked sK(ATP) current induced by the K(ATP) opener pinacidil (IC(50)=0.36+/-0.02 muM), and reversed pinacidil-induced action potential shortening. In inside-out patches, block by HMR 1098 was relieved by increasing MgADP concentrations (1-100 muM). HMR 1098 inhibited pinacidil-activated recombinant Kir6.2/SUR2A channels with a similar IC(50) (0.30+/-0.04 muM), but was less effective when channels were activated by low intracellular ATP. HMR 1098 displaced binding of the pinacidil analogue [(3)H]P1075 to native cardiac membranes with a biphasic inhibition curve. Our results show that HMR 1098 becomes a much less effective inhibitor of sK(ATP) during metabolic stress, and suggest that the lack of effect of HMR 1098 on ischemic cardioprotection reported in some studies may represent loss of block by the drug under these conditions rather than a lack of involvement of sK(ATP) channels. PMID:16099467

Rainbow, R D; Norman, R I; Hudman, D; Davies, N W; Standen, N B

2005-10-01

284

Child Abuse: Definition.  

ERIC Educational Resources Information Center

The purpose of this paper was to elaborate on the definitions of child abuse in order to improve the understanding of child abuse. The definitions given by the U.S. House Joint Committee on Child Abuse in the Child Abuse Prevention and Treatment Act, and in research by Holden (1984), are cited. These definitions refer to the nature of abusive acts…

Wilson, Timothy L.-Y.

285

Medical tele-education system with superhigh-definition (SHD) image viewer  

NASA Astrophysics Data System (ADS)

We have been studying a medical tele-education support system by an individual tutoring system, called CALAT, and a super high definition (SHD) image processing system, called SuperFM-III. Now, we are in a trial operation to use the SuperFM-III for a super high definition image control viewer on the CALAT client side, and have created the courseware of the pathological images. In this paper, we show the concept and the implementation of this system.

Ashihara, Tsukasa; Tsumura, Hiroshi; Urata, Yoji; Hata, Jun-Ichi; Fukuhara, Yoshimi; Ono, Sadayasu

1996-02-01

286

Glutamate and ATP signalling in white matter pathology  

PubMed Central

Excessive signalling by excitatory neurotransmitters like glutamate and ATP can be deleterious to neurons and oligodendroglia, and cause disease. In particular, sustained activation of ?-amino-3-hydroxy-5-methyl-4-isoxazolepropionic acid (AMPA), kainate and N-methyl-d-aspartate (NMDA) receptors damages oligodendrocytes, a feature that depends entirely on Ca2+ overload of the cytoplasm and that can be initiated by disruption of glutamate homeostasis. Thus, inhibition of glutamate uptake by activated microglia can compromise glutamate homeostasis and induce oligodendrocyte excitotoxicity. Moreover, non-lethal, brief activation of kainate receptors in oligodendrocytes rapidly sensitizes these cells to complement attack as a consequence of oxidative stress. In addition to glutamate, ATP signalling can directly trigger oligodendrocyte excitotoxicity via activation of Ca2+-permeable P2X7 purinergic receptors, which mediates ischaemic damage to white matter (WM) and causes lesions that are reminiscent of multiple sclerosis (MS) plaques. Conversely, blockade of P2X7 receptors attenuates post-ischaemic injury to WM and ameliorates chronic experimental autoimmune encephalomyelitis, a model of MS. Importantly, P2X7 expression is elevated in normal-appearing WM in patients with MS, suggesting that signalling through this receptor in oligodendrocytes may be enhanced in this disease. Altogether, these observations reveal novel mechanisms by which altered glutamate and ATP homeostasis can trigger oligodendrocyte death. This review aims at summarizing current knowledge about the mechanisms leading to WM damage as a consequence of altered neurotransmitter signalling, and their relevance to disease. This knowledge will generate new therapeutic avenues to treat more efficiently acute and chronic WM pathology. PMID:21250988

Matute, Carlos

2011-01-01

287

Arrangement of electron transport chain components in bovine mitochondrial supercomplex I1III2IV1  

PubMed Central

The respiratory chain in the inner mitochondrial membrane contains three large multi-enzyme complexes that together establish the proton gradient for ATP synthesis, and assemble into a supercomplex. A 19-Å 3D map of the 1.7-MDa amphipol-solubilized supercomplex I1III2IV1 from bovine heart obtained by single-particle electron cryo-microscopy reveals an amphipol belt replacing the membrane lipid bilayer. A precise fit of the X-ray structures of complex I, the complex III dimer, and monomeric complex IV indicates distances of 13 nm between the ubiquinol-binding sites of complexes I and III, and of 10–11 nm between the cytochrome c binding sites of complexes III and IV. The arrangement of respiratory chain complexes suggests two possible pathways for efficient electron transfer through the supercomplex, of which the shorter branch through the complex III monomer proximal to complex I may be preferred. PMID:21909073

Althoff, Thorsten; Mills, Deryck J; Popot, Jean-Luc; Kühlbrandt, Werner

2011-01-01

288

ATP mediates both activation and inhibition of K(ATP) channel activity via cAMP-dependent protein kinase in insulin-secreting cell lines  

PubMed Central

The single-channel recording technique was employed to investigate the mechanism conferring ATP sensitivity to a metabolite-sensitive K channel in insulin-secreting cells. ATP stimulated channel activity in the 0-10 microM range, but depressed it at higher concentrations. In inside-out patches, addition of the cAMP-dependent protein kinase inhibitor (PKI) reduced channel activity, suggesting that the stimulatory effect of ATP occurs via cAMP-dependent protein kinase- mediated phosphorylation. Raising ATP between 10 and 500 microM in the presence of exogenous PKI progressively reduced the channel activity; it is proposed that this inactivation results from a reduction in kinase activity owing to an ATP-dependent binding of PKI or a protein with similar inhibitory properties to the kinase. A model describing the effects of ATP was developed, incorporating these two separate roles for the nucleotide. Assuming that the efficacy of ATP in controlling the channel activity depends upon the relative concentrations of inhibitor and catalytic subunit associated with the membrane, our model predicts that the channel sensitivity to ATP will vary when the ratio of these two modulators is altered. Based upon this, it is shown that the apparent discrepancy existing between the sensitivity of the channel to low ATP concentrations in the excised patch and the elevated intracellular level of ATP may be explained by postulating a change in the inhibitor/kinase ratio from 1:1 to 3:2 owing to the loss of protein kinase after patch excision. At a low concentration of ATP (10-20 microM), a nonhydrolyzable ATP analogue, AMP-PNP, enhanced the channel activity when present below 10 microM, whereas the analogue blocked the channel activity at higher concentrations. It is postulated that AMP-PNP inhibits the formation of the kinase-inhibitor complex in the former case, and prevents phosphate transfer in the latter. A similar mechanism would explain the interaction between ATP and ADP which is characterized by enhanced activity at low ADP concentrations and blocking at higher concentrations. PMID:2693587

1989-01-01

289

Crucial role for DNA ligase III in mitochondria but not in Xrcc1-dependent repair.  

PubMed

Mammalian cells have three ATP-dependent DNA ligases, which are required for DNA replication and repair. Homologues of ligase I (Lig1) and ligase IV (Lig4) are ubiquitous in Eukarya, whereas ligase III (Lig3), which has nuclear and mitochondrial forms, appears to be restricted to vertebrates. Lig3 is implicated in various DNA repair pathways with its partner protein Xrcc1 (ref. 1). Deletion of Lig3 results in early embryonic lethality in mice, as well as apparent cellular lethality, which has precluded definitive characterization of Lig3 function. Here we used pre-emptive complementation to determine the viability requirement for Lig3 in mammalian cells and its requirement in DNA repair. Various forms of Lig3 were introduced stably into mouse embryonic stem (mES) cells containing a conditional allele of Lig3 that could be deleted with Cre recombinase. With this approach, we find that the mitochondrial, but not nuclear, Lig3 is required for cellular viability. Although the catalytic function of Lig3 is required, the zinc finger (ZnF) and BRCA1 carboxy (C)-terminal-related (BRCT) domains of Lig3 are not. Remarkably, the viability requirement for Lig3 can be circumvented by targeting Lig1 to the mitochondria or expressing Chlorella virus DNA ligase, the minimal eukaryal nick-sealing enzyme, or Escherichia coli LigA, an NAD(+)-dependent ligase. Lig3-null cells are not sensitive to several DNA-damaging agents that sensitize Xrcc1-deficient cells. Our results establish a role for Lig3 in mitochondria, but distinguish it from its interacting protein Xrcc1. PMID:21390132

Simsek, Deniz; Furda, Amy; Gao, Yankun; Artus, Jérôme; Brunet, Erika; Hadjantonakis, Anna-Katerina; Van Houten, Bennett; Shuman, Stewart; McKinnon, Peter J; Jasin, Maria

2011-03-10

290

Argininosuccinate synthetase: a stereochemical study using chiral ATP analogs  

E-print Network

Argininosuccinate synthetase (E. C. 6. 3. 4. 5. 'I was discovered by Ratner in 1947 (I). In its hepatic form, the enzvme catalyz, es the rate-determining step in the biosynthesis of urea (2). The specific condensation reaction catalyzed is shown in Reaction l... to attack the electrophilic a phosphorous of ATP. This adenylated intermediate than decomposes to form argininosuccinate as seen in Reaction 2. 0 HOOC 2 A1P NH2 HR 1 The citations on this and the following pages conform to the style of dournel...

Hess, Tamara Louise Chapman

1984-01-01

291

Assessing ATP binding and hydrolysis by NLR proteins  

PubMed Central

Summary Nucleotide-binding and leucine rich repeat domain-containing proteins (NLR) are central to the formation of many inflammasome complexes. Several inflammasome forming NLR proteins are known to be ATPases, but the nucleotide binding specificity of many remains to be characterized. The oligomerization of NLR proteins and assembly of inflammasomes require the ATP (or other nucleotide) binding activity of the NLR proteins. Quantitative and qualitative studies of the nucleotide binding properties of these proteins are useful tools in studying the regulation of inflammasome activity, and will be outlined in this Chapter. PMID:23852603

Mo, Jinyao; Duncan, Joseph A.

2014-01-01

292

Terrestrial evolution of polymerization of amino acids - Heat to ATP  

NASA Technical Reports Server (NTRS)

Sets of amino acids containing sufficient trifunctional monomer are thermally polymerized at temperatures such as 65 deg; the amino acids order themselves. Various polymers have diverse catalytic activities. The polymers aggregate, in aqueous solution, to cell-like structures having those activities plus emergent properties, e.g. proliferatability. Polyamino acids containing sufficient lysine catalyze conversion of free amino acids, by ATP, to small peptides and a high molecular weight fraction. The lysine-rich proteinoid is active in solution, within suspensions of cell-like particles, or in other particles composed of lysine-rich proteinoid and homopolyribonucleotide. Selectivities are observed. An archaic polyamino acid prelude to coded protein synthesis is indicated.

Fox, S. W.; Nakashima, T.

1981-01-01

293

A Ga(3+)self-assembled fluorescent probe for ATP imaging in vivo.  

PubMed

Adenosine 5'-triphosphate (ATP) is a functional molecule associated with many important biological processes. Fluorescent detection methods for ATP with facile performance and high selectivity are in demand. One of the possible multi-membered arrays assembled between DHBO and Ga(3+) ions was conducted in aqueous solution, which can selectively recognize ATP with fluorescence enhancement from ADP, AMP and other structurally similar nucleoside triphosphates in vitro and in vivo. ATP facilitates the interaction between DHBO and Ga(3+) ions, resulting in the fluorescence increase. The detection limit for ATP was calculated to be 5.49×10(-7)M, which is much lower than that of intracellular concentrations (1-10mM). In addition, DHBO-Ga(3+) can be applied to detect ATP-relevant enzyme activity. PMID:25461153

Xiao, Liangliang; Sun, Shiguo; Pei, Zhichao; Pei, Yuxin; Pang, Yi; Xu, Yongqian

2014-10-18

294

Crystal structure of ATP-binding subunit of an ABC transporter from Geobacillus kaustophilus.  

PubMed

The ATP binding cassette (ABC) transporters, represent one of the largest superfamilies of primary transporters, which are very essential for various biological functions. The crystal structure of ATP-binding subunit of an ABC transporter from Geobacillus kaustophilus has been determined at 1.77 Å resolution. The crystal structure revealed that the protomer has two thick arms, (arm I and II), which resemble 'L' shape. The ATP-binding pocket is located close to the end of arm I. ATP molecule is docked into the active site of the protein. The dimeric crystal structure of ATP-binding subunit of ABC transporter from G. kaustophilus has been compared with the previously reported crystal structure of ATP-binding subunit of ABC transporter from Salmonella typhimurium. PMID:25724946

Manjula, M; Pampa, K J; Kumar, S M; Mukherjee, S; Kunishima, N; Rangappa, K S; Lokanath, N K

2015-03-27

295

Intracellular ATP Concentration Contributes to the Cytotoxic and Cytoprotective Effects of Adenosine  

PubMed Central

Extracellular adenosine (Ade) interacts with cells by two pathways: by activating cell surface receptors at nanomolar/micromolar concentrations; and by interfering with the homeostasis of the intracellular nucleotide pool at millimolar concentrations. Ade shows both cytotoxic and cytoprotective effects; however, the underlying mechanisms remain unclear. In the present study, the effects of adenosine-mediated ATP on cell viability were investigated. Adenosine treatment was found to be cytoprotective in the low intracellular ATP state, but cytotoxic under the normal ATP state. Adenosine-mediated cytotoxicity and cytoprotection rely on adenosine-derived ATP formation, but not via the adenosine receptor pathway. Ade enhanced proteasome inhibition-induced cell death mediated by ATP generation. These data provide a new pathway by which adenosine exerts dual biological effects on cell viability, suggesting an important role for adenosine as an ATP precursor besides the adenosine receptor pathway. PMID:24098558

Guo, Haiping; Liu, Shouting; Huang, Hongbiao; Liu, Ningning; Yang, Changshan; Tang, Ping; Liu, Jinbao

2013-01-01

296

Structure guided simulations illuminate the mechanism of ATP transport through VDAC1  

PubMed Central

The voltage-dependent anion channel (VDAC) mediates metabolite and ion flow across the outer mitochondrial membrane of all eukaryotic cells. The open channel passes millions of ATP molecules per second, while the closed state exhibits no detectable ATP flux. High-resolution structures of VDAC1 revealed a 19-stranded ?-barrel with an ?-helix partially occupying the central pore. To understand ATP permeation through VDAC, we solved the crystal structure of mouse VDAC1 (mVDAC1) in the presence of ATP, revealing a low-affinity binding site. Guided by these coordinates, we initiated hundreds of molecular dynamics (MD) simulations to construct a Markov State Model (MSM) of ATP permeation. These simulations indicate that ATP flows through VDAC using multiple pathways, consistent with our structural data and experimentally determined physiological rates. PMID:24908397

Choudhary, O.P.; Paz, A.; Adelman, J.L.; Colletier, J.P.; Abramson, J.; Grabe, M.

2014-01-01

297

Role of ATP in UV-induced DNA excision repair in human cells  

SciTech Connect

In permeable human fibroblasts, UV-induced DNA excision repair is dependent on ATP, with a K/sub m/ of approximately 1 mM. Omission of ATP from the reaction mix completely inhibits damage-specific incision of DNA, but has little effect on repair patch synthesis proceeding from previously incised sites. UV-induced excision repair in permeable xeroderma pigmentosum (XP) cells complemented with T4 UV endonuclease is also totally dependent on ATP. Because the T4 enzyme is not ATP-dependent, ATP must be required for an endogenous activity other than the incision of damaged DNA. Alkaline elution reveals that, in the absence of ATP, T4 UV endonuclease does incise the DNA of permeable UV-irradiated XP cells, but that the incision rate is stimulated approximately 2-fold by the addition of ATP. This 2-fold stimulation of incision can not, however, be responsible for the absolute ATP dependence of excision repair in UV endonuclease-complemented XP cells. Apparently, although T4 UV endonuclease can incise damaged nuclear DNA in the absence of ATP, the incised sites must also be altered in an ATP-dependent reaction before subsequent steps of the repair process can proceed. This conclusion, coupled with the fact that ATP stimulates incision of damaged nuclear DNA by T4 UV endonuclease and is absolutely required for incision of damaged nuclear DNA by the endogenous human UV endonuclease, suggests that an important function of the early ATP-dependent step in UV-induced excision repair is to make damaged sites in DNA accessible to repair enzymes.

Dresler, S.L.

1986-05-01

298

ATP Changes the Fluorescence Lifetime of Cyan Fluorescent Protein via an Interaction with His148  

Microsoft Academic Search

Recently, we described that ATP induces changes in YFP\\/CFP fluorescence intensities of Fluorescence Resonance Energy Transfer (FRET) sensors based on CFP-YFP. To get insight into this phenomenon, we employed fluorescence lifetime spectroscopy to analyze the influence of ATP on these fluorescent proteins in more detail. Using different donor and acceptor pairs we found that ATP only affected the CFP-YFP based

Jan Willem Borst; Marieke Willemse; Rik Slijkhuis; Gerard van der Krogt; Sergey P. Laptenok; Kees Jalink; Be Wieringa; Jack A. M. Fransen

2010-01-01

299

Vitro packaging of bacteriophage T7 DNA requires ATP. [Escherichia Coli  

SciTech Connect

Removal of nucleoside triphosphates from extracts prepared from bacteriophage T7-infected Escherichia coli results in a stringent requirement for added ATP to form infective phage particles by in vitro packaging of bacteriophage T7 DNA. Optimal packaging efficiency was achieved at a concentration of about 1.25 mM. Other nucleoside triphosphates could be substituted for ATP, but none of the common nucleoside triphosphates was as effective as ATP in promoting in vitro encapsulation.

Masker, W.E.

1982-07-01

300

Blood pressure drop and symptoms during ATP-test under pacing.  

PubMed

We studied systolic blood pressure (SBP) behavior and symptoms during ATP-test in temporary paced patients. SBP drop during ATP-test is only partially prevented by pacing. During DDD paced ATP-test, SBP minimum was lower in symptomatic patients. Considering the role of endogenous adenosine in neurally-mediated syncope (NMS), our results are concurrent with a SBP fall resulting in NMS recurrence under permanent pacing. PMID:18375001

Girerd, N; Rabilloud, M; Flammang, D

2009-05-15

301

Apyrase Suppression Raises Extracellular ATP Levels and Induces Gene Expression and Cell Wall Changes  

E-print Network

.J.R.) and Chemistry (I.F.G., J.W.D., L.J.W.) and Texas Advanced Computing Center (J.S.), University of Texas, Austin, Texas 78712 Plant cells release ATP into their extracellular matrix as they grow, and extracellular ATP) and as they grow (Kim et al., 2006; Wu et al., 2007). Dose-response assays indicate that extracellular ATP (e

Webb, Lauren J.

302

Effects of anions on ATP-activated nonselective cation current in NG108-15 cells.  

PubMed

Extracellular ATP induces a nonselective cation current and elevates intracellular Ca2+ concentration via P2Z receptors in NG108-15 cells. We found that the ATP-induced nonselective cation current became larger in methanesulfonic acid (MS-) than in Cl- external solution. We therefore examined the effects of various external anions on the ATP-induced cation current with the use of the whole cell patch-clamp technique. The concentration-response curves for ATP were obtained in different anionic external solutions. The maximum current density (Imax) and the concentration of agonist that gives 50% of maximum response (EC50) value of ATP were obtained by fitting the curves with the use of the Hill coefficient of 2. The apparent Imax decreased in the order of aspartic acid (Asp-) > MS- > F- > Cl- > Br- > or = I-. The apparent EC50 values for ATP were shifted to the right in the sequence of Asp- < F- < MS- < Br- < Cl- < I-. Thus both Imax and EC50 values were affected by anions, indicating that anions are mixed-type inhibitors of the ATP-induced current. The shift of the EC50 values of ATP indicates that anions interfere with ATP binding to the receptor. External Cl- was a noncompetitive inhibitor with respect to external Na+, a major cation carrying the ATP-induced current. We conclude that extracellular anions inhibit the ATP-induced nonselective cation current at least partly by interfering with ATP binding to the P2Z receptor, which is associated with the nonselective cation channels. PMID:9163387

Kaiho, H; Kimura, J; Matsuoka, I; Nakanishi, H

1997-05-01

303

ATP-Activated Channels in Rat and Bullfrog Sensory Neurons: Concentration Dependence and Kinetics  

Microsoft Academic Search

The concentration dependence and kinetics of ionic currents activated by extracellular adenosine S-triphosphate (ATP) were studied in voltage-clamped dorsal root ganglion neu- rons from rats and bullfrogs. About 40% of neurons of both species responded to ATP with an increase in membrane conductance. The ATP-activated currents were similar in the 2 species, except that currents in rat neurons desensitized faster.

Bruce P. Bean

1990-01-01

304

ATP as a biomarker of viable microorganisms in clean-room facilities  

Microsoft Academic Search

A new firefly luciferase bioluminescence assay method that differentiates free extracellular ATP (dead cells, etc.) from intracellular ATP (viable microbes) was used to determine the viable microbial cleanliness of various clean-room facilities. For comparison, samples were taken from both clean-rooms, where the air was filtered to remove particles >0.5 ?m, and ordinary rooms with unfiltered air. The intracellular ATP was

Kasthuri Venkateswaran; Noriaki Hattori; Myron T. La Duc; Roger Kern

2003-01-01

305

Potentiation of inhibitory synaptic transmission by extracellular ATP in rat suprachiasmatic nuclei.  

PubMed

The hypothalamic suprachiasmatic nuclei (SCN), the circadian master clock in mammals, releases ATP in a rhythm, but the role of extracellular ATP in the SCN is still unknown. In this study, we examined the expression and function of ATP-gated P2X receptors (P2XRs) in the SCN neurons of slices isolated from the brain of 16- to 20-day-old rats. Quantitative RT-PCR showed that the SCN contains mRNA for P2X 1-7 receptors and several G-protein-coupled P2Y receptors. Among the P2XR subunits, the P2X2 > P2X7 > P2X4 mRNAs were the most abundant. Whole-cell patch-clamp recordings from SCN neurons revealed that extracellular ATP application increased the frequency of spontaneous GABAergic IPSCs without changes in their amplitudes. The effect of ATP appears to be mediated by presynaptic P2X2Rs because ATP?S and 2MeS-ATP mimics, while the P2XR antagonist PPADS blocks, the observed enhancement of the frequency of GABA currents. There were significant differences between two SCN regions in that the effect of ATP was higher in the ventrolateral subdivision, which is densely innervated from outside the SCN. Little evidence was found for the presence of P2XR channels in somata of SCN neurons as P2X2R immunoreactivity colocalized with synapsin and ATP-induced current was observed in only 7% of cells. In fura-2 AM-loaded slices, BzATP as well as ADP stimulated intracellular Ca(2+) increase, indicating that the SCN cells express functional P2X7 and P2Y receptors. Our data suggest that ATP activates presynaptic P2X2Rs to regulate inhibitory synaptic transmission within the SCN and that this effect varies between regions. PMID:23637193

Bhattacharya, Anirban; Vavra, Vojtech; Svobodova, Irena; Bendova, Zdena; Vereb, Gyorgy; Zemkova, Hana

2013-05-01

306

ATP levels of chinook salmon (Oncorhynchus tshawytscha) sperm following in vitro exposure to various oxygen tensions  

Microsoft Academic Search

Adenosine triphosphate (ATP) levels in sperm from chinook salmon (Oncorhynchus tshawytscha) were found to be 12.1±1.9 pmol ATP per 106 sperm cells (mean±SEM, n=18). Sperm were stored at 0–2 °C for up to 72 h under 100, 21, and 0% O2. Changes in sperm ATP content of samples maintained under 100 and 21% O2 were indistinguishable, decreasing to 50% of initial values after

D. C. Bencic; M. Krisfalusi; J. G. Cloud; R. L. Ingermann

1999-01-01

307

Studies on the activation by ATP of the 26 S proteasome complex from rat skeletal muscle.  

PubMed Central

The 26 S proteasome complex is thought to catalyse the breakdown of ubiquitinated proteins within eukaryotic cells. In addition it has been found that the complex also degrades short-lived proteins such as ornithine decarboxylase in a ubiquitin-independent manner. Both proteolytic processes are paralleled by the hydrolysis of ATP. Here we show that ATP also affects the hydrolytic activity towards fluorigenic peptide substrates by the 26 S proteasome complex from rat skeletal muscle tissue. Low concentrations of ATP (about 25 microM) optimally activate the so-called chymotryptic and tryptic activity by increasing the rate of peptide hydrolysis but not peptidylglutamylpeptide hydrolysis. Activation of the enzyme by ATP is transient but this effect can be enhanced and prolonged by including in the assay an ATP-regenerating system, indicating that ATP is hydrolysed by the 26 S proteasome complex. Although ATP cannot be substituted for by adenosine 5'-[beta,gamma-methylene]triphosphate or AMP, hydrolysis of the phosphoanhydride bond of ATP seems not to be necessary for the activation process of the proteasome complex, a conclusion drawn from the findings that ATP analogues such as adenosine 5'-[beta,gamma-imido]triphosphate, adenosine 5'-O-[gamma-thio]triphosphate, adenosine 5'-O-[beta-thio]-diphosphate and adenosine 5'-[alpha,beta-methylene]triphosphate give the same effect as ATP, and vanadate does not prevent ATP activation. These effects are independent of the presence of Mg2+. Thus, ATP and other nucleotides may act as allosteric activators of peptide-hydrolysing activities of the 26 S proteasome complex as has also been found with the lon protease from Escherichia coli. Images Figure 1 Figure 2 Figure 3 Figure 4 Figure 5 Figure 6 Figure 7 Figure 8 PMID:7619056

Dahlmann, B; Kuehn, L; Reinauer, H

1995-01-01

308

Enzymatic conversion of ATP to adenosine contributes to ATP-induced inhibition of glutamate release in rat medullary dorsal horn neurons.  

PubMed

Purine nucleotides, such as ATP and ADP, activate ionotropic P2X and metabotropic P2Y receptors to regulate neurotransmitter release in the peripheral as well as central nervous system. Here we report another type of ATP-induced presynaptic modulation of glutamate release in rat medullary dorsal horn neurons. Glutamatergic excitatory postsynaptic currents (EPSCs) induced by electrical stimulation of trigeminal tract were recorded from horizontal brain stem slices using a whole-cell patch clamp technique. ATP decreased the amplitude of glutamatergic EPSCs in a reversible and concentration dependent manner and increased the paired-pulse ratio. In addition, ATP reduced the frequency of miniature EPSCs without affecting the current amplitude, suggesting that ATP acts presynaptically to reduce the probability of glutamate release. The ATP-induced decrease in glutamatergic EPSCs was not affected by P2X and P2Y receptor antagonists, but was completely blocked by DPCPX, a selective adenosine A1 receptor antagonist. The ATP-induced decrease in glutamatergic EPSCs was also inhibited by an inhibitor of tissue nonspecific alkaline phosphatase but not by inhibitors of other enzymes such as ecto-nucleoside triphosphate diphosphohydrolases and ecto-5'-nucleotidases. The results suggest that exogenously applied purine nucleotides are rapidly converted to adenosine by specific enzymes, and subsequently act on presynaptic A1 receptors to inhibit glutamate release from primary afferent terminals. This type of modulation mediated by purine nucleotides may play an important role in regulating nociceptive transmission from orofacial tissues. PMID:25656480

Choi, In-Sun; Cho, Jin-Hwa; Lee, Maan-Gee; Jang, Il-Sung

2015-06-01

309

ATP Requirement for Chloroplast Protein Import Is Set by the Km for ATP Hydrolysis of Stromal Hsp70 in Physcomitrella patens[W  

PubMed Central

The 70-kD family of heat shock proteins (Hsp70s) is involved in a number of seemingly disparate cellular functions, including folding of nascent proteins, breakup of misfolded protein aggregates, and translocation of proteins across membranes. They act through the binding and release of substrate proteins, accompanied by hydrolysis of ATP. Chloroplast stromal Hsp70 plays a crucial role in the import of proteins into plastids. Mutations of an ATP binding domain Thr were previously reported to result in an increase in the Km for ATP and a decrease in the enzyme’s kcat. To ask which chloroplast stromal chaperone, Hsp70 or Hsp93, both of which are ATPases, dominates the energetics of the motor responsible for protein import, we made transgenic moss (Physcomitrella patens) harboring the Km-altering mutation in the essential stromal Hsp70-2 and measured the effect on the amount of ATP required for protein import into chloroplasts. Here, we report that increasing the Km for ATP hydrolysis of Hsp70 translated into an increased Km for ATP usage by chloroplasts for protein import. This thus directly demonstrates that the ATP-derived energy long known to be required for chloroplast protein import is delivered via the Hsp70 chaperones and that the chaperone’s ATPase activity dominates the energetics of the reaction. PMID:24596240

Liu, Li; McNeilage, Robert T.; Shi, Lan-xin; Theg, Steven M.

2014-01-01

310

ATP requirement for chloroplast protein import is set by the Km for ATP hydrolysis of stromal Hsp70 in Physcomitrella patens.  

PubMed

The 70-kD family of heat shock proteins (Hsp70s) is involved in a number of seemingly disparate cellular functions, including folding of nascent proteins, breakup of misfolded protein aggregates, and translocation of proteins across membranes. They act through the binding and release of substrate proteins, accompanied by hydrolysis of ATP. Chloroplast stromal Hsp70 plays a crucial role in the import of proteins into plastids. Mutations of an ATP binding domain Thr were previously reported to result in an increase in the Km for ATP and a decrease in the enzyme's kcat. To ask which chloroplast stromal chaperone, Hsp70 or Hsp93, both of which are ATPases, dominates the energetics of the motor responsible for protein import, we made transgenic moss (Physcomitrella patens) harboring the Km-altering mutation in the essential stromal Hsp70-2 and measured the effect on the amount of ATP required for protein import into chloroplasts. Here, we report that increasing the Km for ATP hydrolysis of Hsp70 translated into an increased Km for ATP usage by chloroplasts for protein import. This thus directly demonstrates that the ATP-derived energy long known to be required for chloroplast protein import is delivered via the Hsp70 chaperones and that the chaperone's ATPase activity dominates the energetics of the reaction. PMID:24596240

Liu, Li; McNeilage, Robert T; Shi, Lan-Xin; Theg, Steven M

2014-03-01

311

A Tetrahymena Hsp90 co-chaperone promotes siRNA loading by ATP-dependent and ATP-independent mechanisms.  

PubMed

The loading of small interfering RNAs (siRNAs) and microRNAs into Argonaute proteins is enhanced by Hsp90 and ATP in diverse eukaryotes. However, whether this loading also occurs independently of Hsp90 and ATP remains unclear. We show that the Tetrahymena Hsp90 co-chaperone Coi12p promotes siRNA loading into the Argonaute protein Twi1p in both ATP-dependent and ATP-independent manners in vitro. The ATP-dependent activity requires Hsp90 and the tetratricopeptide repeat (TPR) domain of Coi12p, whereas these factors are dispensable for the ATP-independent activity. Both activities facilitate siRNA loading by counteracting the Twi1p-binding protein Giw1p, which is important to specifically sort the 26- to 32-nt siRNAs to Twi1p. Although Coi12p lacking its TPR domain does not bind to Hsp90, it can partially restore the siRNA loading and DNA elimination defects of COI12 knockout cells, suggesting that Hsp90- and ATP-independent loading of siRNA occurs in vivo and plays a physiological role in Tetrahymena. PMID:25588944

Woehrer, Sophie L; Aronica, Lucia; Suhren, Jan H; Busch, Clara Jana-Lui; Noto, Tomoko; Mochizuki, Kazufumi

2015-02-12

312

Functional production of the Na+ F1F(O) ATP synthase from Acetobacterium woodii in Escherichia coli requires the native AtpI.  

PubMed

The Na(+) F(1)F(O) ATP synthase of the anaerobic, acetogenic bacterium Acetobacterium woodii has a unique F(O)V(O) hybrid rotor that contains nine copies of a F(O)-like c subunit and one copy of a V(O)-like c(1) subunit with one ion binding site in four transmembrane helices whose cellular function is obscure. Since a genetic system to address the role of different c subunits is not available for this bacterium, we aimed at a heterologous expression system. Therefore, we cloned and expressed its Na(+) F(1)F(O) ATP synthase operon in Escherichia coli. A ?atp mutant of E. coli produced a functional, membrane-bound Na(+) F(1)F(O) ATP synthase that was purified in a single step after inserting a His(6)-tag to its ? subunit. The purified enzyme was competent in Na(+) transport and contained the F(O)V(O) hybrid rotor in the same stoichiometry as in A. woodii. Deletion of the atpI gene from the A. woodii operon resulted in a loss of the c ring and a mis-assembled Na(+) F(1)F(O) ATP synthase. AtpI from E. coli could not substitute AtpI from A. woodii. These data demonstrate for the first time a functional production of a F(O)V(O) hybrid rotor in E. coli and revealed that the native AtpI is required for assembly of the hybrid rotor. PMID:23054076

Brandt, Karsten; Müller, Daniel B; Hoffmann, Jan; Hübert, Christine; Brutschy, Bernd; Deckers-Hebestreit, Gabriele; Müller, Volker

2013-02-01

313

Intracellular ATP Levels are a Pivotal Determinant of Chemoresistance in Colon Cancer Cells  

PubMed Central

Altered metabolism in cancer cells is suspected to contribute to chemoresistance but the precise mechanisms are unclear. Here we show that intracellular ATP levels are a core determinant in the development of acquired cross-drug resistance of human colon cancer cells that harbor different genetic backgrounds. Drug-resistant cells were characterized by defective mitochondrial ATP production, elevated aerobic glycolysis, higher absolute levels of intracellular ATP and enhanced HIF-1?-mediated signaling. Interestingly, direct delivery of ATP into cross-chemoresistant cells destabilized HIF-1? and inhibited glycolysis. Thus, drug-resistant cells exhibit a greater “ATP debt” defined as the extra amount of ATP needed to maintain homeostasis of survival pathways under genotoxic stress. Direct delivery of ATP was sufficient to render drug-sensitive cells drug resistant. Conversely, depleting ATP by cell treatment with an inhibitor of glycolysis, 3-bromopyruvate, was sufficient to sensitize cells cross-resistant to multiple chemotherapeutic drugs. In revealing intracellular ATP levels are a core determinant of chemoresistance in colon cancer cells, our findings may offer a foundation for new improvements to colon cancer treatment. PMID:22084398

Zhou, Yunfei; Tozzi, Federico; Chen, Jinyu; Fan, Fan; Xia, Ling; Wang, Jinrong; Gao, Guang; Zhang, Aijun; Xia, Xuefeng; Brasher, Heather; Widger, William; Ellis, Lee M; Weihua, Zhang

2013-01-01

314

Polymerization of proteins actin and tubulin: the role of nucleotides ATP, GTP  

E-print Network

in both requires complexation by a nucleotide (adenosine triphosphate (ATP) and guanosine triphosphate instability that is based on binding and hydrolysis of a related nucleotide (guanosine triphosphate GTP

315

Inhibition by ATP of calcium oscillations in rat cultured hippocampal neurones  

PubMed Central

The effect of adenosine 5?-triphosphate (ATP) on glutamatergic synaptic transmission in hippocampus was examined by an indicator of intracellular Ca2+ oscillations. These oscillations were postsynaptic responses by glutamate released from presynaptic sites. ATP completely inhibited the oscillations in a concentration-dependent manner. The ATP-induced inhibition was mediated via P2-purinoceptors since ATP exhibited the inhibitory action even in the presence of P1-purinoceptor antagonists. Also non-hydrolysable ATP analogues and uridine 5?-triphosphate (UTP) inhibited the oscillation. The rank order of agonist potency of ATP analogues for inhibition of the Ca2+ oscillation was as follows: 2-methyl-thio-adenosine 5?-triphosphate?ATP>adenosine 5?-O-(3-thiotriphosphate)>UTP>?,?-methylene-adenosine 5?-triphosphate. These inhibitory effects were insensitive to suramin. Judging from this rank order of potency, the inhibitory P2-purinoceptor could be assigned to a subclass of GTP-binding protein coupled-type receptors. The site of action of ATP was thought to be presynaptic since ATP did not affect the postsynaptic Ca2+ responses by glutamate. These results suggest the existence of a presynaptic inhibitory P2-receptor that inhibits glutamate release in the hippocampus. PMID:9298528

Koizumi, Schuichi; Inoue, Kazuhide

1997-01-01

316

The regulation of Sox2 and Sox9 stimulated by ATP in spinal cord astrocytes.  

PubMed

After spinal cord injury (SCI), the level of adenosine triphosphate (ATP) and extracellular matrix (ECM) is increased. Formation of the glial scar is a complex process that is primarily attributed to astrocytic proliferation, and the fibrotic scar results from ECM deposition. In our previous researches, ATP and fibronectin was able to separately stimulate the proliferation of astrocytes. Moreover, fibronectin increases the expression of P2Y1 receptor and offers more binding sites for ATP, which aggravates the proliferation. Meanwhile, ATP was also able to stimulate the release of interleukin (IL)-6 and tumor necrosis factor-? (TNF-?), but fibronectin does not. Recently, it has been reported that over-expressing P2Y1 receptor could promote the level of Sox9. However, the regulation of Sox genes by ATP is still little known in spinal cord astrocytes. In the present study, we discovered that ATP was able to increase the expression of Sox2 and Sox9; fibronectin did not have this direct function. Sox9 was only involved in the proliferation increased by ATP, and Sox2 influenced the release of IL-6 stimulated by ATP. Understanding the critical role of Sox2 and Sox9 mediated by ATP may provide a potential target for therapeutic intervention in spinal cord injury. PMID:25115708

Xia, Maosheng; Zhu, Yue

2015-01-01

317

Extracellular ATP acts as a damage-associated molecular pattern (DAMP) signal in plants  

PubMed Central

As sessile organisms, plants have evolved effective mechanisms to protect themselves from environmental stresses. Damaged (i.e., wounded) plants recognize a variety of endogenous molecules as danger signals, referred to as damage-associated molecular patterns (DAMPs). ATP is among the molecules that are released by cell damage, and recent evidence suggests that ATP can serve as a DAMP. Although little studied in plants, extracellular ATP is well known for its signaling roles in animals, including acting as a DAMP during the inflammatory response and wound healing. If ATP acts outside the cell, then it is reasonable to expect that it is recognized by a plasma membrane-localized receptor. Recently, DORN1, a lectin receptor kinase, was shown to recognize extracellular ATP in Arabidopsis. DORN1 is the founding member of a new purinoceptor subfamily, P2K (P2 receptor kinase), which is plant-specific. P2K1 (DORN1) is required for ATP-induced cellular responses (e.g., cytosolic Ca2+ elevation, MAPK phosphorylation, and gene expression). Genetic analysis of loss-of-function mutants and overexpression lines showed that P2K1 participates in the plant wound response, consistent with the role of ATP as a DAMP. In this review, we summarize past research on the roles and mechanisms of extracellular ATP signaling in plants, and discuss the direction of future research on extracellular ATP as a DAMP signal. PMID:25232361

Tanaka, Kiwamu; Choi, Jeongmin; Cao, Yangrong; Stacey, Gary

2014-01-01

318

Adenosine uptake is the major effector of extracellular ATP toxicity in human cervical cancer cells  

PubMed Central

In cervical cancer, HPV infection and disruption of mechanisms involving cell growth, differentiation, and apoptosis are strictly linked with tumor progression and invasion. Tumor microenvironment is ATP and adenosine rich, suggesting a role for purinergic signaling in cancer cell growth and death. Here we investigate the effect of extracellular ATP on human cervical cancer cells. We find that extracellular ATP itself has a small cytotoxic effect, whereas adenosine formed from ATP degradation by ectonucleotidases is the main factor responsible for apoptosis induction. The level of P2×7 receptor seemed to define the main cytotoxic mechanism triggered by ATP, since ATP itself eliminated a small subpopulation of cells that express high P2×7 levels, probably through its activation. Corroborating these data, blockage or knockdown of P2×7 only slightly reduced ATP cytotoxicity. On the other hand, cell viability was almost totally recovered with dipyridamole, an adenosine transporter inhibitor. Moreover, ATP-induced apoptosis and signaling—p53 increase, AMPK activation, and PARP cleavage—as well as autophagy induction were also inhibited by dipyridamole. In addition, inhibition of adenosine conversion into AMP also blocked cell death, indicating that metabolization of intracellular adenosine originating from extracellular ATP is responsible for the main effects of the latter in human cervical cancer cells. PMID:25103241

Mello, Paola de Andrade; Filippi-Chiela, Eduardo Cremonese; Nascimento, Jéssica; Beckenkamp, Aline; Santana, Danielle Bertodo; Kipper, Franciele; Casali, Emerson André; Nejar Bruno, Alessandra; Paccez, Juliano Domiraci; Zerbini, Luiz Fernando; Wink, Marcia Rosângela; Lenz, Guido; Buffon, Andréia

2014-01-01

319

Chromatophore Vesicles of Rhodobacter capsulatus Contain on Average One FOF1-ATP Synthase Each  

E-print Network

to ATP synthesis, can be spectrophotometrically monitored by electrochromic absorption transients molecules per chromatophore vesicle. Kinetic analysis of the electrochromic transients plus/minus specific

Steinhoff, Heinz-Jürgen

320

ATP-sensitive potassium channel traffic regulation by adenosine and protein kinase C.  

PubMed

ATP-sensitive potassium (K(ATP)) channels activate under metabolic stress to protect neurons and cardiac myocytes. However, excessive channel activation may cause arrhythmia in the heart and silence neurons in the brain. Here, we report that PKC-mediated downregulation of K(ATP) channel number, via dynamin-dependent channel internalization, can act as a brake mechanism to control K(ATP) activation. A dileucine motif in the pore-lining Kir6.2 subunit of K(ATP), but not the site of PKC phosphorylation for channel activation, is essential for PKC downregulation. Whereas K(ATP) activation results in a rapid shortening of the action potential duration (APD) in metabolically inhibited ventricular myocytes, adenosine receptor stimulation and consequent PKC-mediated K(ATP) channel internalization can act as a brake to lessen this APD shortening. Likewise, in hippocampal CA1 neurons under metabolic stress, PKC-mediated, dynamin-dependent K(ATP) channel internalization can also act as a brake to dampen the rapid decline of excitability due to K(ATP) activation. PMID:12741989

Hu, Keli; Huang, Cindy Shen; Jan, Yuh Nung; Jan, Lily Yeh

2003-05-01

321

Activity-driven local ATP synthesis is required for synaptic function  

PubMed Central

Summary Cognitive function is tightly related to metabolic state but the locus of this control is not well understood. Synapses are thought to present large ATP demands however it is unclear how fuel availability and electrical activity impact synaptic ATP levels, and how ATP availability controls synaptic function. We developed a quantitative genetically-encoded optical reporter of presynaptic ATP, Syn-ATP, and find that electrical activity imposes large metabolic demands that are met via activity-driven control of both glycolysis and mitochondrial function. We discovered that the primary source of activity-driven metabolic demand is the synaptic vesicle cycle. In metabolically intact synapses, activity-driven ATP synthesis is well matched to the energetic needs of synaptic function which at steady state results in ~ 106 free ATPs per nerve terminal. Despite this large reservoir of ATP we find that several key aspects of presynaptic function are severely impaired following even brief interruptions in activity-stimulated ATP synthesis. PMID:24529383

Rangaraju, Vidhya; Calloway, Nathaniel; Ryan, Timothy A.

2014-01-01

322

ATP induces mild hypothermia in rats but has a strikingly detrimental impact on focal cerebral ischemia.  

PubMed

Ischemic stroke is a devastating condition lacking effective therapies. A promising approach to attenuate ischemic injury is mild hypothermia. Recent studies show that adenosine nucleotides can induce hypothermia in mice. The purpose of the present study was to test the hypothesis that adenosine 5'-triphosphate (ATP) induces mild hypothermia in rats and reduces ischemic brain injury. We found that intraperitoneal injections of ATP decreased core body temperature in a dose-dependent manner; the dose appropriate for mild hypothermia was 2 g/kg. When ATP-induced hypothermia was applied to stroke induced by middle cerebral artery occlusion, however, a neuroprotective effect was not observed. Instead, the infarct volume grew even larger in ATP-treated rats. This was accompanied by an increased rate of seizure events, hemorrhagic transformation, and higher mortality. Continuous monitoring of physiologic parameters revealed that ATP reduced heartbeat rate and blood pressure. ATP also increased blood glucose, accompanied by severe acidosis and hypocalcemia. Western blotting showed that ATP decreased levels of both phospho-Akt and total-Akt in the cortex. Our results reveal that, despite inducing hypothermia, ATP is not appropriate for protecting the brain against stroke. Instead, we show for the first time that ATP treatment is associated with exaggerated ischemic outcomes and dangerous systemic side effects. PMID:23072747

Zhang, Meijuan; Li, Wenjin; Niu, Guangming; Leak, Rehana K; Chen, Jun; Zhang, Feng

2013-01-01

323

Temporal and mechanistic dissociation of ATP and adenosine release during ischaemia in the mammalian hippocampus1  

PubMed Central

Abstract Adenosine is well known to be released during cerebral metabolic stress and is believed to be neuroprotective. ATP release under similar circumstances has been much less studied. We have now used biosensors to measure and compare in real time the release of ATP and adenosine during in vitro ischaemia in hippocampal slices. ATP release only occurred following the anoxic depolarisation, whereas adenosine release was apparent almost immediately after the onset of ischaemia. ATP release required extracellular Ca2+. By contrast adenosine release was enhanced by removal of extracellular Ca2+, whilst TTX had no effect on either ATP release or adenosine release. Blockade of ionotropic glutamate receptors substantially enhanced ATP release, but had only a modest effect on adenosine release. Carbenoxolone, an inhibitor of gap junction hemichannels, also greatly enhanced ischaemic ATP release, but had little effect on adenosine release. The ecto-ATPase inhibitor ARL 67156, whilst modestly enhancing the ATP signal detected during ischaemia, had no effect on adenosine release. Adenosine release during ischaemia was reduced by pre-treament with homosysteine thiolactone suggesting an intracellular origin. Adenosine transport inhibitors did not inhibit adenosine release, but instead they caused a twofold increase of release. Our data suggest that ATP and adenosine release during ischaemia are for the most part independent processes with distinct underlying mechanisms. These two purines will consequently confer temporally distinct influences on neuronal and glial function in the ischaemic brain. PMID:17459147

Frenguelli, Bruno G; Wigmore, Geoffrey; Llaudet, Enrique; Dale, Nicholas

2007-01-01

324

Mechanism of an ATP-independent Protein Disaggregase  

PubMed Central

The ability of molecular chaperones to overcome the misfolding and aggregation of proteins is essential for the maintenance of proper protein homeostasis in all cells. Thus far, the best studied disaggregase systems are the Clp/Hsp100 family of “ATPases associated with various cellular activities” (AAA+) ATPases, which use mechanical forces powered by ATP hydrolysis to remodel protein aggregates. An alternative system to disassemble large protein aggregates is provided by the 38-kDa subunit of the chloroplast signal recognition particle (cpSRP43), which uses binding energy with its substrate proteins to drive disaggregation. The mechanism of this novel chaperone remains unclear. Here, molecular genetics and structure-activity analyses show that the action of cpSRP43 can be dissected into two steps with distinct molecular requirements: (i) initial recognition, during which cpSRP43 binds specifically to a recognition motif displayed on the surface of the aggregate; and (ii) aggregate remodeling, during which highly adaptable binding interactions of cpSRP43 with hydrophobic transmembrane domains of the substrate protein compete with the packing interactions within the aggregate. This establishes a useful framework to understand the molecular mechanism by which binding interactions from a molecular chaperone can be used to overcome protein aggregates in the absence of external energy input from ATP. PMID:23519468

Jaru-Ampornpan, Peera; Liang, Fu-Cheng; Nisthal, Alex; Nguyen, Thang X.; Wang, Pengcheng; Shen, Kuang; Mayo, Steven L.; Shan, Shu-ou

2013-01-01

325

Mechanosensitive ATP release maintains proper mucus hydration of airways.  

PubMed

The clearance of mucus from the airways protects the lungs from inhaled noxious and infectious materials. Proper hydration of the mucus layer enables efficient mucus clearance through beating of cilia on airway epithelial cells, and reduced clearance of excessively concentrated mucus occurs in patients with chronic obstructive pulmonary disease and cystic fibrosis. Key steps in the mucus transport process are airway epithelia sensing and responding to changes in mucus hydration. We reported that extracellular adenosine triphosphate (ATP) and adenosine were important luminal autocrine and paracrine signals that regulated the hydration of the surface of human airway epithelial cultures through their action on apical membrane purinoceptors. Mucus hydration in human airway epithelial cultures was sensed by an interaction between cilia and the overlying mucus layer: Changes in mechanical strain, proportional to mucus hydration, regulated ATP release rates, adjusting fluid secretion to optimize mucus layer hydration. This system provided a feedback mechanism by which airways maintained mucus hydration in an optimum range for cilia propulsion. Understanding how airway epithelia can sense and respond to changes in mucus properties helps us to understand how the mucus clearance system protects the airways in health and how it fails in lung diseases such as cystic fibrosis. PMID:23757023

Button, Brian; Okada, Seiko F; Frederick, Charles Brandon; Thelin, William R; Boucher, Richard C

2013-06-11

326

ATP-Independent Hydrocarbon Formation Catalyzed by Isolated Nitrogenase Cofactors  

PubMed Central

Nitrogenase is a highly complex and uniquely versatile metalloenzyme that is capable of reducing a broad spectrum of substrates, such as dinitrogen (N2), carbon monoxide (CO) and cyanide (CN-), under ambient conditions.[1-4] The molybdenum (Mo)- and vanadium (V)-nitrogenases are two homologous members of this enzyme family, both utilizing a specific reductase (Fe protein) to donate electrons to the cofactor site (FeMoco or FeVco) of a catalytic component (MoFe or VFe protein) during catalysis. The buried location of cofactor poses a challenge to electron transfer in this process, rendering it strictly dependent on ATP-assisted formation of an electron transport chain—within a complex between the reductase and the catalytic component—that extends all the way from the [Fe4S4] cluster of the former, via the P-cluster, to the cofactor site of the latter.[5] On the other hand, both FeMoco and FeVco can be extracted as intact entities into organic solvents,[6-8] spurring interest in seeking an ATP-independent reaction system, in which electrons can be directly delivered to the isolated cofactors for substrate reduction. In particular, the recent discovery that nitrogenases can reduce CO to hydrocarbons[3,4] makes it an attractive task to explore the capacity of cofactors to directly catalyze the formation of hydrocarbons from CO, as well as CN-—another carbonaceous molecule that is isoelectronic to CO. PMID:22253035

Lee, Chi Chung; Hu, Yilin; Ribbe, Markus W.

2012-01-01

327

President's Commission on Sustainability Charter Article I Purpose and Definitions  

E-print Network

. Article III ­ Organization #12;Section 1: Decision Making Decisions of the PCS shall be by a majority votePresident's Commission on Sustainability Charter Article I ­ Purpose and Definitions Section 1 sustainability for public institutions of higher education. To creatively address sustainability, the PCS

Duchowski, Andrew T.

328

Composition and primary structure of the F1F0 ATP synthase from the obligately anaerobic bacterium Clostridium thermoaceticum.  

PubMed Central

The subunit composition and primary structure of the proton-translocating F1F0 ATP synthase have been determined in Clostridium thermoaceticum. The isolated enzyme has a subunit composition identical to that of the F1F0 ATP synthase purified from Clostridium thermoautotrophicum (A. Das, D. M. Ivey, and L. G. Ljungdahl, J. Bacteriol. 179:1714-1720, 1997), both having six different polypeptides. The molecular masses of the six subunits were 60, 50, 32, 17, 19, and 8 kDa, and they were identified as alpha, beta, gamma, delta, epsilon, and c, respectively, based on their reactivity with antibodies against the F1 ATPase purified from C. thermoautotrophicum and by comparing their N-terminal amino acid sequences with that deduced from the cloned genes of the C. thermoaceticum atp operon. The subunits a and b found in many bacterial ATP synthases could not be detected either in the purified ATP synthase or crude membranes of C. thermoaceticum. The C. thermoaceticum atp operon contained nine genes arranged in the order atpI (i), atpB (a), atpE (c), atpF (b), atpH (delta), atpA (alpha), atpG (gamma), atpD (beta), and atpC (epsilon). The deduced protein sequences of the C. thermoaceticum ATP synthase subunits were comparable with those of the corresponding subunits from Escherichia coli, thermophilic Bacillus strain PS3, Rhodospirillum rubrum, spinach chloroplasts, and the cyanobacterium Synechococcus strain PCC 6716. The analysis of total RNA by Northern hybridization experiments reveals the presence of transcripts (mRNA) of the genes i, a, and b subunits not found in the isolated enzyme. Analysis of the nucleotide sequence of the atp genes reveals overlap of the structural genes for the i and a subunits and the presence of secondary structures (in the b gene) which could influence the posttranscriptional regulation of the corresponding genes. PMID:9171425

Das, A; Ljungdahl, L G

1997-01-01

329

Identification of ATP-Binding Regions in the RyR1 Ca2+ Release Channel  

PubMed Central

ATP is an important modulator of gating in type 1 ryanodine receptor (RyR1), also known as a Ca2+ release channel in skeletal muscle cells. The activating effect of ATP on this channel is achieved by directly binding to one or more sites on the RyR1 protein. However, the number and location of these sites have yet to be determined. To identify the ATP-binding regions within RyR1 we used 2N3ATP-2?,3?-Biotin-LC-Hydrazone (BioATP-HDZ), a photo-reactive ATP analog to covalently label the channel. We found that BioATP-HDZ binds RyR1 specifically with an IC50?=?0.6±0.2 mM, comparable with the reported EC50 for activation of RyR1 with ATP. Controlled proteolysis of labeled RyR1 followed by sequence analysis revealed three fragments with apparent molecular masses of 95, 45 and 70 kDa that were crosslinked by BioATP-HDZ and identified as RyR1 sequences. Our analysis identified four glycine-rich consensus motifs that can potentially constitute ATP-binding sites and are located within the N-terminal 95-kDa fragment. These putative nucleotide-binding sequences include amino acids 699–704, 701–706, 1081–1084 and 1195–1200, which are conserved among the three RyR isoforms. Located next to the N-terminal disease hotspot region in RyR1, these sequences may communicate the effects of ATP-binding to channel function by tuning conformational motions within the neighboring cytoplasmic regulatory domains. Two other labeled fragments lack ATP-binding consensus motifs and may form non-canonical ATP-binding sites. Based on domain topology in the 3D structure of RyR1 it is also conceivable that the identified ATP-binding regions, despite their wide separation in the primary sequence, may actually constitute the same non-contiguous ATP-binding pocket within the channel tetramer. PMID:23144945

Popova, Olga B.; Baker, Mariah R.; Tran, Tina P.; Le, Tri; Serysheva, Irina I.

2012-01-01

330

Leucine culture reveals that ATP synthase functions as a fuel sensor in pancreatic beta-cells.  

PubMed

Our goal was to investigate whether leucine culture affects beta-cell glucose sensing. One-day culture of rat islets with 10 mM leucine had no effect on glucose-induced insulin secretion. One-week leucine culture decreased the threshold for glucose-induced insulin secretion and increased maximal insulin secretion at 30 mM glucose. Glucose-induced cytosolic free Ca(2+) was increased at 1 week but not at 1 day of leucine culture. Without glucose, ATP content was not different with or without leucine culture for 1 week. With 20 mM glucose, ATP content was higher by 1.5-fold in islets cultured for 1 week with leucine than those without leucine. Microarray experiments indicated that culture of RINm5F cells with leucine increased expression of ATP synthase beta subunit 3.2-fold, which was confirmed by real time reverse transcription-PCR analysis (3.0- +/- 0.4-fold) in rat islets at 1 week but not after 1 day with leucine culture. Down-regulation of ATP synthase beta subunit by siRNA decreased INS1 cell ATP content and insulin secretion with 20 mM glucose. Overexpression of ATP synthase beta subunit in INS1 cell increased insulin secretion in the presence of 5 and 20 mM glucose. In conclusion, one-week leucine culture of rat islets up-regulated ATP synthase and increased ATP content, which resulted in elevated [Ca(2+)] levels and more insulin exocytosis by glucose. Depletion of ATP synthase beta subunit with siRNA produced opposite effects. These data reveal the fuel-sensing role of mitochondrial ATP synthase in the control of ATP production from glucose and the control of glucose-induced insulin secretion. PMID:15489222

Yang, Jichun; Wong, Ryan K; Wang, Xujing; Moibi, Jacob; Hessner, Martin J; Greene, Scott; Wu, Jianmei; Sukumvanich, Siam; Wolf, Bryan A; Gao, Zhiyong

2004-12-24

331

Mechanical Modulation of ATP-binding Affinity of V1-ATPase*  

PubMed Central

V1-ATPase is a rotary motor protein that rotates the central shaft in a counterclockwise direction hydrolyzing ATP. Although the ATP-binding process is suggested to be the most critical reaction step for torque generation in F1-ATPase (the closest relative of V1-ATPase evolutionarily), the role of ATP binding for V1-ATPase in torque generation has remained unclear. In the present study, we performed single-molecule manipulation experiments on V1-ATPase from Thermus thermophilus to investigate how the ATP-binding process is modulated upon rotation of the rotary shaft. When V1-ATPase showed an ATP-waiting pause, it was stalled at a target angle and then released. Based on the response of the V1-ATPase released, the ATP-binding probability was determined at individual stall angles. It was observed that the rate constant of ATP binding (kon) was exponentially accelerated with forward rotation, whereas the rate constant of ATP release (koff) was exponentially reduced. The angle dependence of the koff of V1-ATPase was significantly smaller than that of F1-ATPase, suggesting that the ATP-binding process is not the major torque-generating step in V1-ATPase. When V1-ATPase was stalled at the mean binding angle to restrict rotary Brownian motion, kon was evidently slower than that determined from free rotation, showing the reaction rate enhancement by conformational fluctuation. It was also suggested that shaft of V1-ATPase should be rotated at least 277° in a clockwise direction for efficient release of ATP under ATP-synthesis conditions. PMID:23155048

Tirtom, Naciye Esma; Okuno, Daichi; Nakano, Masahiro; Yokoyama, Ken; Noji, Hiroyuki

2013-01-01

332

Activation by ATP of a P2U 'nucleotide' receptor in an exocrine cell.  

PubMed Central

1. We employed the perforated patch whole-cell technique to investigate the effects of ATP and other related nucleotides on membrane conductances in avian exocrine salt gland cells. 2. ATP (10 microM-1 mM) evoked an increase in maxi-K+ and Cl- conductances with a reversal potential of -35 mV. At lower concentrations of ATP (< or = 100 microM) responses were generally oscillatory with a sustained response observed at higher concentrations (> or = 200 microM). 3. Both oscillatory and sustained responses were abolished by the removal of bath Ca2+. In cells preincubated in extracellular saline containing reduced Ca2+, the application of ATP resulted in a transient increase in current. 4. As increasing concentrations of ATP (and related nucleotides) evoked a graded sequence of events with little run-down we were able to establish a rank order of potency in single cells. The order of potency of ATP analogues and agonists of the various P2-receptor subtypes was UTP > ATP = 2-methylthio-ATP > ADP. Adenosine (1 microM-1 mM), AMP (1 microM-1 mM), alpha,beta-methylene-ATP (1 microM-1 mM) and beta,gamma-methylene-ATP (1 microM-1 mM) were without effect. 5. In conclusion, although unable to preclude a role for a P2Y-receptor, our results suggest that ATP binds to a P2U-receptor increasing [Ca2+]i and subsequently activating Ca(2+)-sensitive K+ and Cl- currents. PMID:7670734

Martin, S. C.; Shuttleworth, T. J.

1995-01-01

333

Contribution of ATP and nitric oxide to NANC inhibitory transmission in rat pyloric sphincter.  

PubMed Central

1. Changes in isometric tension were recorded from circular muscle strips of rat pyloric sphincter in vitro, in response to electrical field stimulation and exogenously applied muscle relaxants. 2. Concentration-response relationships were studied for relaxation to exogenously applied adenosine 5'-triphosphate (ATP) and two analogues, 2-methylthioATP (2-MeSATP) and alpha,beta-methylene ATP (alpha,beta-MeATP). These drugs evoked concentration-dependent relaxation of rat pyloric sphincter with an order of potency 2-MeSATP > ATP >> alpha,beta-MeATP, indicating the presence of P2y-purinoceptors. The IC50 value of each nucleotide was: 2-MeSATP, 5.0 x 10(-8); ATP, 7.9 x 10(-6) M; alpha,beta-MeATP showed only slight activity at a concentration of 0.1 mM. 3. Frequency-response relationships for relaxations evoked by electrical field stimulation (EFS) were studied in the absence and presence of 10 microM NG-nitro-L-arginine methyl ester (L-NAME, an inhibitor of nitric oxide (NO) synthesis) and 20 microM reactive blue 2 (a P2y-purinoceptor antagonist). It was found that these substances significantly reduced the relaxant response of rat pyloric sphincter to EFS by 40% and 50% respectively. In the presence of both L-NAME and reactive blue 2 the responses were reduced by 75%. 4. Concentration-response relationships were studied for ATP and 2-MeSATP in the presence of L-NAME. It was found that L-NAME did not significantly inhibit the relaxant responses to these drugs. 5. Concentration-response relationships for ATP and noradrenaline were studied in the presence of reactive blue 2 (20 microM); the P2y-antagonist significantly inhibited the relaxant response to ATP, but not that to noradrenaline.(ABSTRACT TRUNCATED AT 250 WORDS) Images Figure 6 PMID:7532079

Soediono, P; Burnstock, G

1994-01-01

334

Diverse roles of K(ATP) channels learned from Kir6.2 genetically engineered mice.  

PubMed

The regulation of insulin secretion from pancreatic beta-cells depends critically on the activities of their plasma membrane ion channels. ATP-sensitive K+ channels (K(ATP) channels) are present in many cells and regulate a variety of cellular functions by coupling cell metabolism with membrane potential. The activity of the K(ATP) channels in pancreatic beta-cells is regulated by changes in the ATP and ADP concentrations (ATP/ADP ratio) caused by glucose metabolism. Thus, the K(ATP) channels are the ATP and ADP sensors in the regulation of glucose-induced insulin secretion. K(ATP) channels are also the target of sulfonylureas, which are widely used in the treatment of type 2 diabetes. Molecular cloning of the two subunits of the pancreatic beta-cell K(ATP) channel, Kir6.2 (an inward rectifier K+ channel member) and SUR1 (a receptor for sulfonylureas), has provided great insight into its structure and function. Kir6.2 subunits form the K+ ion-permeable pore and primarily confer inhibition of the channels by ATP, while SUR1 subunits confer activation of the channels by MgADP and K+ channel openers, such as diazoxide, as well as inhibition by sulfonylureas. The SUR1 subunits also enhance the sensitivity of the channels to ATP. To determine the physiological roles of K(ATP) channels directly, we have generated two kinds of genetically engineered mice: mice expressing a dominant-negative form of Kir6.2 specifically in the pancreatic beta-cells (Kir6.2G132S Tg mice) and mice lacking Kir6.2 (Kir6.2 knockout mice). Studies of these mice elucidated various roles of the K(ATP) channels in endocrine pancreatic function: 1) the K(ATP) channels are the major determinant of the resting membrane potential of pancreatic beta-cells, 2) both glucose- and sulfonylurea-induced membrane depolarization of beta-cells require closure of the K(ATP) channels, 3) both glucose- and sulfonylurea-induced rises in intracellular calcium concentration in beta-cells require closure of the K(ATP) channels, 4) both glucose- and sulfonylurea-induced insulin secretions are mediated principally by the K(ATP) channel-dependent pathway, 5) the K(ATP) channels are important for beta-cell survival and architecture of the islets, 6) the K(ATP) channels are important in the differentiation of islet cells, and 7) the K(ATP) channels in glucose-responsive cells generally participate in coupling glucose sensing with cell excitability. Interestingly, despite the severe defect in glucose-induced insulin secretion, Kir6.2 knockout mice show only a very mild impairment in glucose tolerance. However, when the knockout mice become obese with age, they develop fasting hyperglycemia and glucose intolerance, while neither fasting hyperglycemia nor glucose intolerance is evident in the aged knockout mice without obesity, suggesting that both the genetic defect in glucose-induced insulin secretion and the acquired insulin resistance due to environmental factors are necessary to develop diabetes in Kir6.2 knockout mice. Thus, Kir6.2G132S Tg mice and Kir6.2 knockout mice provide a model of type 2 diabetes and clarify the various roles of K(ATP) channels in endocrine pancreatic function. PMID:10868950

Seino, S; Iwanaga, T; Nagashima, K; Miki, T

2000-03-01

335

A Membrane-Bound Archaeal Lon Protease Displays ATP-Independent Proteolytic Activity towards Unfolded Proteins and ATP-Dependent Activity for Folded Proteins  

Microsoft Academic Search

In contrast to the eucaryal 26S proteasome and the bacterial ATP-dependent proteases, little is known about the energy-dependent proteolysis in members of the third domain, Archaea. We cloned a gene homologous to ATP-dependent Lon protease from a hyperthermophilic archaeon and observed the unique properties of the archaeal Lon. Lon from Thermococcus kodakaraensis KOD1 (LonTk) is a 70-kDa protein with an

Toshiaki Fukui; Tomohiro Eguchi; Haruyuki Atomi; Tadayuki Imanaka

2002-01-01

336

Involvement of 3Na +\\/2K + ATP-ase and Pi3 kinase in the response of skeletal muscle ATP-sensitive K + channels to insulin  

Microsoft Academic Search

The modulation of ATP-sensitive K+ channel (KATP) by insulin plays a role in neuromuscular disorders associated to altered K+ homeostasis. However, the mechanisms by which insulin modulates KATP channels are not known. Here, the insulin-dependent 3Na+\\/2K+ ATP-ase and Pi-3 kinase pathways were explored by using patch-clamp techniques. High and low affinity inhibition of KATP channels by ouabain was observed in

Domenico Tricarico; Loredana Montanari; Diana Conte Camerino

2003-01-01

337

A mitochondrial import receptor for the ADP/ATP carrier.  

PubMed

We have identified a mitochondrial outer membrane protein of 72 kd (MOM72) that exhibits the properties of an import receptor for the ADP/ATP carrier (AAC), the most abundant mitochondrial protein. Monospecific antibodies and Fab fragments against MOM72 selectively inhibit import of AAC at the level of specific binding to the mitochondria. AAC bound to the mitochondrial surface is coprecipitated with antibodies against MOM72 after lysis of mitochondria with detergent. MOM72 thus has a complementary function to that of MOM19, which acts as an import receptor for the majority of mitochondrial proteins studied so far but not for the AAC. The import pathway of the precursor of MOM72 appears to involve MOM19 as receptor. PMID:2163763

Söllner, T; Pfaller, R; Griffiths, G; Pfanner, N; Neupert, W

1990-07-13

338

NASA ATP Force Measurement Technology Capability Strategic Plan  

NASA Technical Reports Server (NTRS)

The Aeronautics Test Program (ATP) within the National Aeronautics and Space Administration (NASA) Aeronautics Research Mission Directorate (ARMD) initiated a strategic planning effort to re-vitalize the force measurement capability within NASA. The team responsible for developing the plan included members from three NASA Centers (Langley, Ames and Glenn) as well as members from the Air Force s Arnold Engineering and Development Center (AEDC). After visiting and discussing force measurement needs and current capabilities at each participating facility as well as selected force measurement companies, a strategic plan was developed to guide future NASA investments. This paper will provide the details of the strategic plan and include asset management, organization and technology research and development investment priorities as well as efforts to date.

Rhew, Ray D.

2008-01-01

339

Structure and Mechanism of Soybean ATP Sulfurylase and the Committed Step in Plant Sulfur Assimilation*  

PubMed Central

Enzymes of the sulfur assimilation pathway are potential targets for improving nutrient content and environmental stress responses in plants. The committed step in this pathway is catalyzed by ATP sulfurylase, which synthesizes adenosine 5?-phosphosulfate (APS) from sulfate and ATP. To better understand the molecular basis of this energetically unfavorable reaction, the x-ray crystal structure of ATP sulfurylase isoform 1 from soybean (Glycine max ATP sulfurylase) in complex with APS was determined. This structure revealed several highly conserved substrate-binding motifs in the active site and a distinct dimerization interface compared with other ATP sulfurylases but was similar to mammalian 3?-phosphoadenosine 5?-phosphosulfate synthetase. Steady-state kinetic analysis of 20 G. max ATP sulfurylase point mutants suggests a reaction mechanism in which nucleophilic attack by sulfate on the ?-phosphate of ATP involves transition state stabilization by Arg-248, Asn-249, His-255, and Arg-349. The structure and kinetic analysis suggest that ATP sulfurylase overcomes the energetic barrier of APS synthesis by distorting nucleotide structure and identifies critical residues for catalysis. Mutations that alter sulfate assimilation in Arabidopsis were mapped to the structure, which provides a molecular basis for understanding their effects on the sulfur assimilation pathway. PMID:24584934

Herrmann, Jonathan; Ravilious, Geoffrey E.; McKinney, Samuel E.; Westfall, Corey S.; Lee, Soon Goo; Baraniecka, Patrycja; Giovannetti, Marco; Kopriva, Stanislav; Krishnan, Hari B.; Jez, Joseph M.

2014-01-01

340

Three-Dimensional Structures Reveal Multiple ADP/ATP Binding Modes  

SciTech Connect

The creation of synthetic enzymes with predefined functions represents a major challenge in future synthetic biology applications. Here, we describe six structures of de novo proteins that have been determined using protein crystallography to address how simple enzymes perform catalysis. Three structures are of a protein, DX, selected for its stability and ability to tightly bind ATP. Despite the addition of ATP to the crystallization conditions, the presence of a bound but distorted ATP was found only under excess ATP conditions, with ADP being present under equimolar conditions or when crystallized for a prolonged period of time. A bound ADP cofactor was evident when Asp was substituted for Val at residue 65, but ATP in a linear configuration is present when Phe was substituted for Tyr at residue 43. These new structures complement previously determined structures of DX and the protein with the Phe 43 to Tyr substitution [Simmons, C. R., et al. (2009) ACS Chem. Biol. 4, 649-658] and together demonstrate the multiple ADP/ATP binding modes from which a model emerges in which the DX protein binds ATP in a configuration that represents a transitional state for the catalysis of ATP to ADP through a slow, metal-free reaction capable of multiple turnovers. This unusual observation suggests that design-free methods can be used to generate novel protein scaffolds that are tailor-made for catalysis.

C Simmons; C Magee; D Smith; L Lauman; J Chaput; J Allen

2011-12-31

341

A Computational Analysis of ATP Binding of SV40 Large Tumor Antigen Helicase Motor  

PubMed Central

Simian Virus 40 Large Tumor Antigen (LTag) is an efficient helicase motor that unwinds and translocates DNA. The DNA unwinding and translocation of LTag is powered by ATP binding and hydrolysis at the nucleotide pocket between two adjacent subunits of an LTag hexamer. Based on the set of high-resolution hexameric structures of LTag helicase in different nucleotide binding states, we simulated a conformational transition pathway of the ATP binding process using the targeted molecular dynamics method and calculated the corresponding energy profile using the linear response approximation (LRA) version of the semi-macroscopic Protein Dipoles Langevin Dipoles method (PDLD/S). The simulation results suggest a three-step process for the ATP binding from the initial interaction to the final tight binding at the nucleotide pocket, in which ATP is eventually “locked” by three pairs of charge-charge interactions across the pocket. Such a “cross-locking” ATP binding process is similar to the binding zipper model reported for the F1-ATPase hexameric motor. The simulation also shows a transition mechanism of Mg2+ coordination to form the Mg-ATP complex during ATP binding, which is accompanied by the large conformational changes of LTag. This simulation study of the ATP binding process to an LTag and the accompanying conformational changes in the context of a hexamer leads to a refined cooperative iris model that has been proposed previously. PMID:19779548

Shi, Yemin; Liu, Hanbin; Gai, Dahai; Ma, Jianpeng; Chen, Xiaojiang S.

2009-01-01

342

Crystal Structure of the Bifunctional ATP Sulfurylase APS kinase from the Chemolithotrophic  

E-print Network

and adenosine-5-phosphosul- fate (APS) kinase activities. These enzymes are usually segregated on two separate-phosphoadenosine-5- phosphosulfate; ATS, ATP sulfurylase; APS, adenosine-5- phosphosulfate; ASK, APS kinase. ECrystal Structure of the Bifunctional ATP Sulfurylase ­ APS kinase from the Chemolithotrophic

Fisher, Andrew J.

343

Surface charge and properties of cardiac ATP-sensitive K+ channels  

Microsoft Academic Search

ATP-sensitive K + (KATP) channels are present in a wide variety of tissues. The sensitivity of these channels to closure by cytosolic ATP (ATPi) varies significantly among different tissues and even within the same tissue. The purpose of this study was to test the hypothesis that negative surface charges modulate the sensitivity of the KATe channels to ATPi by influencing

NICHOLAS DEUTSCH; JAMES N. WEISS

1994-01-01

344

Phylogeny and Identification of Enterococci by atpA Gene Sequence Analysis  

PubMed Central

The relatedness among 91 Enterococcus strains representing all validly described species was investigated by comparing a 1,102-bp fragment of atpA, the gene encoding the alpha subunit of ATP synthase. The relationships observed were in agreement with the phylogeny inferred from 16S rRNA gene sequence analysis. However, atpA gene sequences were much more discriminatory than 16S rRNA for species differentiation. All species were differentiated on the basis of atpA sequences with, at a maximum, 92% similarity. Six members of the Enterococcus faecium species group (E. faecium, E. hirae, E. durans, E. villorum, E. mundtii, and E. ratti) showed >99% 16S rRNA gene sequence similarity, but the highest value of atpA gene sequence similarity was only 89.9%. The intraspecies atpA sequence similarities for all species except E. faecium strains varied from 98.6 to 100%; the E. faecium strains had a lower atpA sequence similarity of 96.3%. Our data clearly show that atpA provides an alternative tool for the phylogenetic study and identification of enterococci. PMID:15872246

Naser, S.; Thompson, F. L.; Hoste, B.; Gevers, D.; Vandemeulebroecke, K.; Cleenwerck, I.; Thompson, C. C.; Vancanneyt, M.; Swings, J.

2005-01-01

345

Long term continuous ATP regeneration by enzymes of the alcohol fermentation pathway and kinases of yeast  

Microsoft Academic Search

Continuous ATP regeneration from adenosine using enzymes of the alcohol fermentation pathway, adenosine kinase and adenylate kinase of baker's yeast was investigated using a reactor equipped with a semipermeable membrane. The addition of DTT, which protected the thiol groups of some enzymes against oxidation, increased the duration of the period of ATP formation from 42 h (previously the longest period)

Masanori Asada; Kazuharu Yanamoto; Kazuhiro Nakanishi; Ryuichi Matsuno; Akira Kirnura; Tadashi Kamikubo

1981-01-01

346

Decrease of intracellular ATP content downregulated UCP2 expression in mouse hepatocytes  

Microsoft Academic Search

Mitochondrial uncoupling protein 2 (UCP2) plays an important role in regulating energy metabolism. We previously reported that UCP2 expression in steatotic livers is increased which leads to diminished hepatic ATP stores and renders steatotic hepatocytes vulnerable to ischemic damage. In this study, reagents that inhibit the production of ATP were used to mimic an ischemic state in the liver in

Gang Cheng; Carmen C Polito; Julia K Haines; Stephen F Shafizadeh; Ryan N Fiorini; Xin Zhou; Michael G Schmidt; Kenneth D Chavin

2003-01-01

347

The Contribution of Red Blood Cell Dynamics to Intrinsic Viscosity and Functional ATP Release  

NASA Astrophysics Data System (ADS)

In shear flow, red blood cells (RBCs) exhibit a variety of behaviors such as rouleaux formation, tumbling, swinging, and tank-treading. The physiological consequences of these dynamic behaviors are not understood. In vivo, ATP is known to signal vasodilation; however, to our knowledge, no one has deciphered the relevance of RBC microrheology to the functional release of ATP. Previously, we correlated RBC deformation and ATP release in microfluidic constrictions (Wan et al., 2008). In this work, a cone-plate rheometer is used to shear a low hematocrit solution of RBCs at varying viscosity ratios (?) between the inner cytoplasmic hemoglobin and the outer medium, to determine the intrinsic viscosity of the suspension. Further, using a luciferin-luciferase enzymatic reaction, we report the relative ATP release at varying shear rates. Results indicate that for ? = 1.6, 3.8 and 11.1, ATP release is constant up to 500 s-1, which suggests that the tumbling-tanktreading transition does not alter ATP release in pure shear. For lower viscosity ratios, ? = 1.6 and 3.8, at 500 s-1 a change in slope occurs in the intrinsic viscosity data and is marked by an increase in ATP release. Based on microfluidic observations, this simultaneous change in viscosity and ATP release occurs within the tank-treading regime.

Forsyth, Alison; Abkarian, Manouk; Wan, Jiandi; Stone, Howard

2010-11-01

348

Significance of ATP, carbon, and caloric content of meiobenthic nematodes in partitioning benthic biomass  

Microsoft Academic Search

Benthic, free-living marine nematodes from two stations, one subtidal, one intertidal, in the North Inlet Estuary, South Carolina, USA, have been characterized by measurement of adenosine triphosphate (ATP), carbon, caloric content, and ash-free dry weight. Two methods of extracting the organisms from the sediment were used. Resulting carbon to ATP ratios and population density data from ongoing North Inlet meiofauna

J. P. Sikora; W. B. Sikora; C. W. Erkenbrecher; B. C. Coull

1977-01-01

349

Autism Post-Mortem Neuroinformatic Resource: The Autism Tissue Program (ATP) Informatics Portal  

ERIC Educational Resources Information Center

The Autism Tissue Program (ATP) was established to oversee and manage brain donations related to neurological research in autism. The ATP Informatics Portal (www.atpportal.org) is an integrated data access system based on Oracle technology, developed to provide access for researchers to information on this rare tissue resource. It also permits…

Brimacombe, Michael B.; Pickett, Richard; Pickett, Jane

2007-01-01

350

Molecular, Functional, and Pathological Aspects of the Mitochondrial ADP/ATP Carrier  

NSDL National Science Digital Library

In providing the cell with ATP generated by oxidative phosphorylation, the mitochondrial ADP/ATP carrier plays a central role in aerobic eukaryotic cells. Combining biochemical, genetic, and structural approaches contributes to understanding the molecular mechanism of this essential transport system, the dysfunction of which is implicated in neuromuscular diseases.

C. Dahout-Gonzalez (UMR 5092 CEA-CNRS-Université Joseph Fourier Département de Réponse et Dynamique Cellulaires)

2006-08-01

351

Cation Transport Coupled to ATP Hydrolysis by the (Na, K)-ATPase: An Integrated, Animated Model  

ERIC Educational Resources Information Center

An Adobe[R] animation is presented for use in undergraduate Biochemistry courses, illustrating the mechanism of Na[superscript +] and K[superscript +] translocation coupled to ATP hydrolysis by the (Na, K)-ATPase, a P[subscript 2c]-type ATPase, or ATP-powered ion pump that actively translocates cations across plasma membranes. The enzyme is also…

Leone, Francisco A.; Furriel, Rosa P. M.; McNamara, John C.; Horisberger, Jean D.; Borin, Ivana A.

2010-01-01

352

ATP: A Coherent View for School Advanced Level Studies in Biology.  

ERIC Educational Resources Information Center

Discusses how instruction of biological concepts as ATP cellular energetics is related to fundamental physical science understandings. Reviews areas of common misconceptions and confusions. Summarizes results of a study which investigated students' knowledge and perception of difficulty associated with the topic of energy and ATP. (ML)

Gayford, Chris

1986-01-01

353

ATP as a biomarker of viable microorganisms in clean-room facilities  

NASA Technical Reports Server (NTRS)

A new firefly luciferase bioluminescence assay method that differentiates free extracellular ATP (dead cells, etc.) from intracellular ATP (viable microbes) was used to determine the viable microbial cleanliness of various clean-room facilities. For comparison, samples were taken from both clean-rooms, where the air was filtered to remove particles >0.5 microm, and ordinary rooms with unfiltered air. The intracellular ATP was determined after enzymatically degrading the sample's free ATP. Also for comparison, cultivable microbial populations were counted on nutrient-rich trypticase soy agar (TSA) plates. Both the cultivable and ATP-based determinations indicate that the microbial burden was lower in clean-room facilities than in ordinary rooms. However, there was no direct correlation between the two sets of measurements because the two assays measured very different populations. A large fraction of the samples yielded no colony formers on TSA, but were positive for intracellular ATP. Subsequently, genomic DNA was isolated directly from selected samples and 16S rDNA fragments were cloned and sequenced, identifying nearest neighbors, many of which are known to be noncultivable in the media employed. It was concluded that viable microbial contamination can be reliably monitored by measurement of intracellular ATP, and that this method may be considered superior to cultivable colony counts due to its speed and its ability to report the presence of viable but noncultivable organisms. When the detection of nonviable microbes is of interest, the ATP assay can be supplemented with DNA analysis.

Venkateswaran, Kasthuri; Hattori, Noriaki; La Duc, Myron T.; Kern, Roger

2003-01-01

354

A SPECTROPHOTOMETRIC ASSAY TO MEASURE RUBISCO ACTIVASE ACTIVATION ACTIVITY UNDER VARYING ATP:ADP RATIOS  

Technology Transfer Automated Retrieval System (TEKTRAN)

The ratio of ATP to ADP in the stroma is an important regulatory mechanism for controlling the activation state of Rubisco via Rubisco activase (activase). Understanding the response of activase to a varying ATP:ADP ratio should reveal insights into the regulation of photosynthesis. However, the cur...

355

ATP and ADP hydrolysis in brain membranes of zebrafish (Danio rerio)  

E-print Network

ATP and ADP hydrolysis in brain membranes of zebrafish (Danio rerio) Eduardo Pacheco Rico1 , Mario membranes of zebrafish (Danio rerio). This enzyme was cation-dependent, with a maximal rate for ATP and ADP. The presence of a NTPDase in brain membranes of zebrafish may be important for the modulation of nucleotide

Eizirik, Eduardo

356

mTOR Regulates Lysosomal ATP-Sensitive Two-Pore Na+  

E-print Network

membrane. LysoNaATP determines the sensitivity of endolysosome's resting membrane potential to Na's membrane potential, pH stability, and amino acid homeostasis. Mutant mice lacking lysoNaATP have much upon nutrient removal and mTOR translocation off the lysosomal membrane, and controls the lysosome

Clapham, David E.

357

Structural, Biochemical and Genetic Characterization of Dissimilatory ATP Sulfurylase from Allochromatium vinosum  

PubMed Central

ATP sulfurylase (ATPS) catalyzes a key reaction in the global sulfur cycle by reversibly converting inorganic sulfate (SO42?) with ATP to adenosine 5?-phosphosulfate (APS) and pyrophosphate (PPi). In this work we report on the sat encoded dissimilatory ATP sulfurylase from the sulfur-oxidizing purple sulfur bacterium Allochromatium vinosum. In this organism, the sat gene is located in one operon and co-transcribed with the aprMBA genes for membrane-bound APS reductase. Like APS reductase, Sat is dispensible for growth on reduced sulfur compounds due to the presence of an alternate, so far unidentified sulfite-oxidizing pathway in A. vinosum. Sulfate assimilation also proceeds independently of Sat by a separate pathway involving a cysDN-encoded assimilatory ATP sulfurylase. We produced the purple bacterial sat-encoded ATP sulfurylase as a recombinant protein in E. coli, determined crucial kinetic parameters and obtained a crystal structure in an open state with a ligand-free active site. By comparison with several known structures of the ATPS-APS complex in the closed state a scenario about substrate-induced conformational changes was worked out. Despite different kinetic properties ATPS involved in sulfur-oxidizing and sulfate-reducing processes are not distinguishable on a structural level presumably due to the interference between functional and evolutionary processes. PMID:24073218

Parey, Kristian; Demmer, Ulrike; Warkentin, Eberhard; Wynen, Astrid; Ermler, Ulrich; Dahl, Christiane

2013-01-01

358

Visualized discrimination of ATP from ADP and AMP through collapse of supramolecular gels.  

PubMed

A supramolecular gel was fabricated through mixing of a cationic gelator with methyl orange. The addition of ATP into the gel caused a distinct gel-collapse, whereas ADP and AMP preserved the gel formation. This observation provided a simple visualized way to discriminate ATP from AMP and ADP. PMID:25205284

Yang, Dong; Liu, Changxia; Zhang, Li; Liu, Minghua

2014-10-28

359

Irgarol inhibits the synthesis of ATP in mitochondria from rat liver.  

PubMed

The interactions of Irgarol with rat liver mithocondrial have been investigated. The results indicate that Irgarol inhibits the ATP synthesis. The analysis of the various steps involved in the ATP synthesis suggests that the inhibition is due to the opening of small-size pores. PMID:16979217

Bragadin, Marcantonio; Cima, Francesca; Ballarin, Loriano; Manente, Sabrina

2006-12-01

360

Effect of ATP-sensitive K+ channel regulators on cystic fibrosis transmembrane conductance regulator chloride currents  

Microsoft Academic Search

A B S T R AC T The cystic fibrosis transmembrane conductance regulator (CFTR) is a C1- channel that is regulated by cAMP-dependent phosphorylation and by intracel- lular ATP. Intracellular ATP also regulates a class of K + channels that have a distinct pharmacology: they are inhibited by sulfonylureas and activated by a novel class of drugs called K ÷

DAVID N. SHEPPARD; MICHAEL J. WEmH

1992-01-01

361

Human K(ATP) channelopathies: diseases of metabolic homeostasis.  

PubMed

Assembly of an inward rectifier K+ channel pore (Kir6.1/Kir6.2) and an adenosine triphosphate (ATP)-binding regulatory subunit (SUR1/SUR2A/SUR2B) forms ATP-sensitive K+ (KATP) channel heteromultimers, widely distributed in metabolically active tissues throughout the body. KATP channels are metabolism-gated biosensors functioning as molecular rheostats that adjust membrane potential-dependent functions to match cellular energetic demands. Vital in the adaptive response to (patho)physiological stress, KATP channels serve a homeostatic role ranging from glucose regulation to cardioprotection. Accordingly, genetic variation in KATP channel subunits has been linked to the etiology of life-threatening human diseases. In particular, pathogenic mutations in KATP channels have been identified in insulin secretion disorders, namely, congenital hyperinsulinism and neonatal diabetes. Moreover, KATP channel defects underlie the triad of developmental delay, epilepsy, and neonatal diabetes (DEND syndrome). KATP channelopathies implicated in patients with mechanical and/or electrical heart disease include dilated cardiomyopathy (with ventricular arrhythmia; CMD1O) and adrenergic atrial fibrillation. A common Kir6.2 E23K polymorphism has been associated with late-onset diabetes and as a risk factor for maladaptive cardiac remodeling in the community-at-large and abnormal cardiopulmonary exercise stress performance in patients with heart failure. The overall mutation frequency within KATP channel genes and the spectrum of genotype-phenotype relationships remain to be established, while predicting consequences of a deficit in channel function is becoming increasingly feasible through systems biology approaches. Thus, advances in molecular medicine in the emerging field of human KATP channelopathies offer new opportunities for targeted individualized screening, early diagnosis, and tailored therapy. PMID:20033705

Olson, Timothy M; Terzic, Andre

2010-07-01

362

Alternative translational initiation of ATP sulfurylase underlying dual localization of sulfate assimilation pathways in plastids and cytosol in Arabidopsis thaliana  

PubMed Central

Plants assimilate inorganic sulfate into sulfur-containing vital metabolites. ATP sulfurylase (ATPS) is the enzyme catalyzing the key entry step of the sulfate assimilation pathway in both plastids and cytosol in plants. Arabidopsis thaliana has four ATPS genes (ATPS1, –2, –3, and –4) encoding ATPS pre-proteins containing N-terminal transit peptide sequences for plastid targeting, however, the genetic identity of the cytosolic ATPS has remained unverified. Here we show that Arabidopsis ATPS2 dually encodes plastidic and cytosolic ATPS isoforms, differentiating their subcellular localizations by initiating translation at AUGMet1 to produce plastid-targeted ATPS2 pre-proteins or at AUGMet52 or AUGMet58 within the transit peptide to have ATPS2 stay in cytosol. Translational initiation of ATPS2 at AUGMet52 or AUGMet58 was verified by expressing a tandem-fused synthetic gene, ATPS2(5?UTR-His12):Renilla luciferase:ATPS2(Ile13?Val77):firefly luciferase, under a single constitutively active CaMV 35S promoter in Arabidopsis protoplasts and examining the activities of two different luciferases translated in-frame with split N-terminal portions of ATPS2. Introducing missense mutations at AUGMet52 and AUGMet58 significantly reduced the firefly luciferase activity, while AUGMet52 was a relatively preferred site for the alternative translational initiation. The activity of luciferase fusion protein starting at AUGMet52 or AUGMet58 was not modulated by changes in sulfate conditions. The dual localizations of ATPS2 in plastids and cytosol were further evidenced by expression of ATPS2-GFP fusion proteins in Arabidopsis protoplasts and transgenic lines, while they were also under control of tissue-specific ATPS2 promoter activity found predominantly in leaf epidermal cells, guard cells, vascular tissues and roots. PMID:25601874

Bohrer, Anne-Sophie; Yoshimoto, Naoko; Sekiguchi, Ai; Rykulski, Nicholas; Saito, Kazuki; Takahashi, Hideki

2015-01-01

363

Evaluation of intramitochondrial ATP levels identifies G0/G1 switch gene 2 as a positive regulator of oxidative phosphorylation  

PubMed Central

The oxidative phosphorylation (OXPHOS) system generates most of the ATP in respiring cells. ATP-depleting conditions, such as hypoxia, trigger responses that promote ATP production. However, how OXPHOS is regulated during hypoxia has yet to be elucidated. In this study, selective measurement of intramitochondrial ATP levels identified the hypoxia-inducible protein G0/G1 switch gene 2 (G0s2) as a positive regulator of OXPHOS. A mitochondria-targeted, FRET-based ATP biosensor enabled us to assess OXPHOS activity in living cells. Mitochondria-targeted, FRET-based ATP biosensor and ATP production assay in a semiintact cell system revealed that G0s2 increases mitochondrial ATP production. The expression of G0s2 was rapidly and transiently induced by hypoxic stimuli, and G0s2 interacts with OXPHOS complex V (FoF1-ATP synthase). Furthermore, physiological enhancement of G0s2 expression prevented cells from ATP depletion and induced a cellular tolerance for hypoxic stress. These results show that G0s2 positively regulates OXPHOS activity by interacting with FoF1-ATP synthase, which causes an increase in ATP production in response to hypoxic stress and protects cells from a critical energy crisis. These findings contribute to the understanding of a unique stress response to energy depletion. Additionally, this study shows the importance of assessing intramitochondrial ATP levels to evaluate OXPHOS activity in living cells. PMID:24344269

Kioka, Hidetaka; Kato, Hisakazu; Fujikawa, Makoto; Tsukamoto, Osamu; Suzuki, Toshiharu; Imamura, Hiromi; Nakano, Atsushi; Higo, Shuichiro; Yamazaki, Satoru; Matsuzaki, Takashi; Takafuji, Kazuaki; Asanuma, Hiroshi; Asakura, Masanori; Minamino, Tetsuo; Shintani, Yasunori; Yoshida, Masasuke; Noji, Hiroyuki; Kitakaze, Masafumi; Komuro, Issei; Asano, Yoshihiro; Takashima, Seiji

2014-01-01

364

Modeling regulation of cardiac KATP and L-type Ca2+ currents by ATP, ADP, and Mg2+  

NASA Technical Reports Server (NTRS)

Changes in cytosolic free Mg(2+) and adenosine nucleotide phosphates affect cardiac excitability and contractility. To investigate how modulation by Mg(2+), ATP, and ADP of K(ATP) and L-type Ca(2+) channels influences excitation-contraction coupling, we incorporated equations for intracellular ATP and MgADP regulation of the K(ATP) current and MgATP regulation of the L-type Ca(2+) current in an ionic-metabolic model of the canine ventricular myocyte. The new model: 1), quantitatively reproduces a dose-response relationship for the effects of changes in ATP on K(ATP) current, 2), simulates effects of ADP in modulating ATP sensitivity of K(ATP) channel, 3), predicts activation of Ca(2+) current during rapid increase in MgATP, and 4), demonstrates that decreased ATP/ADP ratio with normal total Mg(2+) or increased free Mg(2+) with normal ATP and ADP activate K(ATP) current, shorten action potential, and alter ionic currents and intracellular Ca(2+) signals. The model predictions are in agreement with experimental data measured under normal and a variety of pathological conditions.

Michailova, Anushka; Saucerman, Jeffrey; Belik, Mary Ellen; McCulloch, Andrew D.

2005-01-01

365

Failure of the Cystic Fibrosis Transmembrane Conductance Regulator to Conduct ATP  

NASA Astrophysics Data System (ADS)

The cystic fibrosis transmembrane conductance regulator (CFTR) is chloride ion channel regulated by protein kinase A and adenosine triphosphate (ATP). Loss of CFTR-mediated chloride ion conductance from the apical plasma membrane of epithelial cells is a primary physiological lesion in cystic fibrosis. CFTR has also been suggested to function as an ATP channel, although the size of the ATP anion is much larger than the estimated size of the CFTR pore. ATP was not conducted through CFTR in intact organs, polarized human lung cell lines, stably transfected mammalian cell lines, or planar lipid bilayers reconstituted with CFTR protein. These findings suggest that ATP permeation through the CFTR is unlikely to contribute to the normal function of CFTR or to the pathogenesis of cystic fibrosis.

Reddy, M. M.; Quinton, P. M.; Haws, C.; Wine, J. J.; Grygorczyk, R.; Tabcharani, J. A.; Hanrahan, J. W.; Gunderson, K. L.; Kopito, R. R.

1996-03-01

366

Food Allergies DEFINITIONS  

E-print Network

are a digestive system response and are much more common than food allergies. Food Allergy vs. Food Intolerance's digestive system or when a person is unable to properly digest a food. SYMPTOMS: Symptoms of an AllergicFood Allergies DEFINITIONS: Definition of a Food Allergy: Immune system response to a food

Maxwell, Bruce D.

367

Cachexia: A new definition  

Microsoft Academic Search

Summary On December 13th and 14th a group of scientists and clinicians met in Washington, DC, for the cachexia consensus conference. At the present time, there is no widely agreed upon operational definition of cachexia. The lack of a definition accepted by clinician and researchers has limited identification and treatment of cachectic patient as well as the development and approval

William J. Evans; John E. Morley; Josep Argiles; Connie Bales; Vickie Baracos; Denis Guttridge; Aminah Jatoi; Kamyar Kalantar-Zadeh; Herbert Lochs; Giovanni Mantovani; Daniel Marks; William E. Mitch; Maurizio Muscaritoli; Armine Najand; Piotr Ponikowski; Filippo Rossi Fanelli; Morrie Schambelan; Annemie Schols; Michael Schuster; David Thomas; Robert Wolfe; Stefan D. Anker

2008-01-01

368

Regulation of CFTR Cl- channel gating by ADP and ATP analogues  

PubMed Central

The cystic fibrosis gene product (CFTR) is a chloride channel which, once phosphorylated, is regulated by nucleotide phosphates (Anderson, M. P., and M. J. Welsh. 1992. Science. 257:1701-1704; Venglarik, C. J., B. D. Schultz, R. A. Frizzell, and R. J. Bridges. 1994. Journal of General Physiology. 104:123-146). Nucleotide triphosphates initiate channel activity, while nucleotide diphosphates and nonhydrolyzable ATP analogues do not. To further characterize the role of these compounds on CFTR channel activity we examined their effects on chloride channel currents in excised inside-out membrane patches from CFTR transfected mouse L cells. ADP competitively inhibited ATP-dependent CFTR channel gating with a Ki of 16 +/- 9 microM. AMP neither initiated CFTR channel gating nor inhibited ATP-dependent CFTR channel gating. Similarly, ATP analogues with substitutions in the phosphate chain, including AMPCPP, AMPPCP, AMPPNP, and ATP gamma S failed to support CFTR channel activity when present at the cytoplasmic face of the membrane and none of these analogues, when present at three to 10-fold excess of ATP, detectably altered ATP-dependent CFTR channel gating. These data suggest that none of these ATP analogues interact with the ATP regulatory site of CFTR which we previously characterized and, therefore, no inference regarding a requirement for ATP hydrolysis in CFTR channel gating can be made from their failure to support channel activity. Furthermore, the data indicate that this nucleotide regulatory site is exquisitely sensitive to alterations in the phosphate chain of the nucleotide; only a nonsubstituted nucleotide di- or triphosphate interacts with this regulatory site. Alternative recording conditions, such as the presence of kinase and a reduction in temperature to 25 degrees C, result in a previously uncharacterized kinetic state of CFTR which may exhibit distinctly different nucleotide dependencies. PMID:7539480

1995-01-01

369

Intracellular ATP does not inhibit Slo2.1 K+ channels  

PubMed Central

Abstract Under normal physiological conditions, the open probability of Slo2.1 K+ channels is low. Elevation of cytosolic [Na+] and [Cl?] caused by ischemia or rapid electrical pacing of cells increases the open probability of Slo2.1 channels and the resulting outward current can stabilize the resting state of cells. Initial characterization of heterologously expressed human Slo2.1 indicated that these channels were inhibited by physiological levels of intracellular ATP. However, a subsequent study found that intracellular ATP had no effect on Slo2.1 channels. Here, we re?examine the effects of intracellular ATP on cloned human Slo2.1 channels heterologously expressed in Xenopus oocytes. Our studies provide both direct and indirect evidence that changes in intracellular [ATP] have no effect on Slo2.1 channels. First, we directly examined the effects of intracellular ATP on Slo2.1 channel activity in excised inside?out macropatches from Xenopus oocytes. Application of 5 mmol/L ATP to the intracellular solution did not inhibit Slo2.1 currents activated by niflumic acid. Second, we lowered the [ATP]i in whole oocytes using the metabolic inhibitor NaN3. Depletion of [ATP]i in oocytes by 3 mmol/L NaN3 rapidly activated heterologously expressed KATP channels, but did not increase wild?type Slo2.1 channel currents activated by niflumic acid or currents conducted by constitutively active mutant (E275D) Slo2.1 channels. Third, mutation of a conserved residue in the ATP binding consensus site in the C?terminal domain of the channel did not enhance the magnitude of Slo2.1 current as expected if binding to this site inhibited channel function. We conclude that Slo2.1 channels are not inhibited by intracellular ATP. PMID:25214519

Garg, Priyanka; Sanguinetti, Michael C.

2014-01-01

370

Intracellular ATP does not inhibit Slo2.1 K+ channels.  

PubMed

Under normal physiological conditions, the open probability of Slo2.1 K(+) channels is low. Elevation of cytosolic [Na(+)] and [Cl(-)] caused by ischemia or rapid electrical pacing of cells increases the open probability of Slo2.1 channels and the resulting outward current can stabilize the resting state of cells. Initial characterization of heterologously expressed human Slo2.1 indicated that these channels were inhibited by physiological levels of intracellular ATP. However, a subsequent study found that intracellular ATP had no effect on Slo2.1 channels. Here, we re-examine the effects of intracellular ATP on cloned human Slo2.1 channels heterologously expressed in Xenopus oocytes. Our studies provide both direct and indirect evidence that changes in intracellular [ATP] have no effect on Slo2.1 channels. First, we directly examined the effects of intracellular ATP on Slo2.1 channel activity in excised inside-out macropatches from Xenopus oocytes. Application of 5 mmol/L ATP to the intracellular solution did not inhibit Slo2.1 currents activated by niflumic acid. Second, we lowered the [ATP]i in whole oocytes using the metabolic inhibitor NaN3. Depletion of [ATP]i in oocytes by 3 mmol/L NaN3 rapidly activated heterologously expressed KATP channels, but did not increase wild-type Slo2.1 channel currents activated by niflumic acid or currents conducted by constitutively active mutant (E275D) Slo2.1 channels. Third, mutation of a conserved residue in the ATP binding consensus site in the C-terminal domain of the channel did not enhance the magnitude of Slo2.1 current as expected if binding to this site inhibited channel function. We conclude that Slo2.1 channels are not inhibited by intracellular ATP. PMID:25214519

Garg, Priyanka; Sanguinetti, Michael C

2014-09-01

371

Cyano-bridged Mn(III)-M(III) single-chain magnets with M(III)=Co(III), Fe(III), Mn(III), and Cr(III).  

PubMed

A series of isostructural cyano-bridged Mn(III)(h.s.)-M(III)(l.s.) alternating chains, [Mn(III)(5-TMAMsalen)M(III)(CN)(6)]?4H(2)O (5-TMAMsalen(2-)=N,N'-ethylenebis(5-trimethylammoniomethylsalicylideneiminate), Mn(III)(h.s.)=high-spin Mn(III), M(III)(l.s.)=low-spin Co(III), Mn-Co; Fe(III), Mn-Fe; Mn(III), Mn-Mn; Cr(III), Mn-Cr) was synthesized by assembling [Mn(III)(5-TMAMsalen)](3+) and [M(III)(CN)(6)](3-). The chains present in the four compounds, which crystallize in the monoclinic space group C2/c, are composed of an [-Mn(III)-NC-M(III)-CN-] repeating motif, for which the -NC-M(III)-CN- motif is provided by the [M(III)(CN)(6)](3-) moiety adopting a trans bridging mode between [Mn(III)(5-TMAMsalen)](3+) cations. The Mn(III) and M(III) ions occupy special crystallographic positions: a C(2) axis and an inversion center, respectively, forming a highly symmetrical chain with only one kind of cyano bridge. The Jahn-Teller axis of the Mn(III)(h.s.) ion is perpendicular to the N(2)O(2) plane formed by the 5-TMAMsalen tetradentate ligand. These Jahn-Teller axes are all perfectly aligned along the unique chain direction without a bending angle, although the chains are corrugated with an Mn-N(axis) -C angle of about 144°. In the crystal structures, the chains are well separated with the nearest inter-chain M???M distance being relatively large at 9?Å due to steric hindrance of the bulky trimethylammoniomethyl groups of the 5-TMAMsalen ligand. The magnetic properties of these compounds have been thoroughly studied. Mn-Fe and Mn-Mn display intra-chain ferromagnetic interactions, whereas Mn-Cr is characterized by an antiferromagnetic exchange that induces a ferrimagnetic spin arrangement along the chain. Detailed analyses of both static and dynamic magnetic properties have demonstrated without ambiguity the single-chain magnet (SCM) behavior of these three systems, whereas Mn-Co is merely paramagnetic with S(Mn)=2 and D/k(B)=-5.3?K (D being a zero-field splitting parameter). At low temperatures, the Mn-M compounds with M=Fe, Mn, and Cr display remarkably large M versus H hysteresis loops for applied magnetic fields along the easy magnetic direction that corresponds to the chain direction. The temperature dependence of the associated relaxation time for this series of compounds systematically exhibits a crossover between two Arrhenius laws corresponding to infinite-chain and finite-chain regimes for the SCM behavior. These isostructural hetero-spin SCMs offer a unique series of alternating [-Mn-NC-M-CN-] chains, enabling physicists to test theoretical SCM models between the Ising and Heisenberg limits. PMID:22344962

Miyasaka, Hitoshi; Madanbashi, Tomokura; Saitoh, Ayumi; Motokawa, Natsuko; Ishikawa, Ryuta; Yamashita, Masahiro; Bahr, Stefan; Wernsdorfer, Wolfgang; Clérac, Rodolphe

2012-03-26

372

4. System Definition 16 4. System Definition  

E-print Network

of subsystems, it is thus, in an analysis, possible to subdivide a problem into manageable portions, this is perhaps, at a first glance, self-evident but the demarcation regarding the receiving system can give rise to some problems. Figure 4.4 Illustration of system definition Let us assume that the receiving structure

Berlin,Technische Universität

373

A delayed ATP-elicited K+ current in freshly isolated smooth muscle cells from mouse aorta  

PubMed Central

Adenosine 5?-triphosphate (ATP) activated two sequential responses in freshly isolated mouse aortic smooth muscle cells. In the first phase, ATP activated Ca2+-dependent K+ or Cl? currents and the second phase was the activation of a delayed outward current with a reversal potential of ?75.9±1.4?mV. A high concentration of extracellular K+ (130?mM) shifted the reversal potential of the delayed ATP-elicited current to ?3.5±1.3?mV. The known K+-channel blockers, iberiotoxin, charybdotoxin, glibenclamide, apamin, 4-aminopyridine, Ba2+ and tetraethylammonium chloride all failed to inhibit the delayed ATP-elicited K+ current. Removal of ATP did not decrease the amplitude of the ATP-elicited current back to the control values. The simultaneous recording of cytosolic free Ca2+ and membrane currents revealed that the first phase of the ATP-elicited response is associated with an increase in intracellular Ca2+, while the second delayed phase develops after the return of cytosolic free Ca2+ to control levels. ATP did not activate Ca2+-dependent K+ currents, but did elicit Ca2+-independent K+ currents, in cells dialyzed with ethylene glycol-bis (2-aminoethylether)-N,N,N?,N?-tetraacetic acid (EGTA). The delay of activation of Ca2+-independent currents decreased from 10.5+3.4 to 1.27±0.33?min in the cells dialyzed with 2?mM EGTA. Adenosine alone failed to elicit a Ca2+-independent K+ current but simultaneous application of ATP and adenosine activated the delayed K+ current. Intracellular dialysis of cells with guanosine 5?-O-(2-thiodiphosphate) transformed the Ca2+-independent ATP-elicited response from a sustained to a transient one. A phospholipase C inhibitor, U73122 (1??M), was shown to abolish the delayed ATP-elicited response. These results indicate that the second phase of the ATP-elicited response was a delayed Ca2+-independent K+ current activated by exogenous ATP. This phase might represent a new vasoregulatory pathway in vascular smooth muscle cells. PMID:16258525

Serir, Karima; Hayoz, Sebastien; Fanchaouy, Mohammed; Bény, Jean-Louis; Bychkov, Rostislav

2005-01-01

374

The helicase-like domains of type III restriction enzymes trigger long-range diffusion along DNA.  

PubMed

Helicases are ubiquitous adenosine triphosphatases (ATPases) with widespread roles in genome metabolism. Here, we report a previously undescribed functionality for ATPases with helicase-like domains; namely, that ATP hydrolysis can trigger ATP-independent long-range protein diffusion on DNA in one dimension (1D). Specifically, using single-molecule fluorescence microscopy we show that the Type III restriction enzyme EcoP15I uses its ATPase to switch into a distinct structural state that diffuses on DNA over long distances and long times. The switching occurs only upon binding to the target site and requires hydrolysis of ~30 ATPs. We define the mechanism for these enzymes and show how ATPase activity is involved in DNA target site verification and 1D signaling, roles that are common in DNA metabolism: for example, in nucleotide excision and mismatch repair. PMID:23599494

Schwarz, Friedrich W; Tóth, Júlia; van Aelst, Kara; Cui, Guanshen; Clausing, Sylvia; Szczelkun, Mark D; Seidel, Ralf

2013-04-19

375

Crystal structure of the R-protein of the multisubunit ATP-dependent restriction endonuclease NgoAVII.  

PubMed

The restriction endonuclease (REase) NgoAVII is composed of two proteins, R.NgoAVII and N.NgoAVII, and shares features of both Type II restriction enzymes and Type I/III ATP-dependent restriction enzymes (see accompanying paper Zaremba et al., 2014). Here we present crystal structures of the R.NgoAVII apo-protein and the R.NgoAVII C-terminal domain bound to a specific DNA. R.NgoAVII is composed of two domains: an N-terminal nucleolytic PLD domain; and a C-terminal B3-like DNA-binding domain identified previously in BfiI and EcoRII REases, and in plant transcription factors. Structural comparison of the B3-like domains of R.NgoAVII, EcoRII, BfiI and the plant transcription factors revealed a conserved DNA-binding surface comprised of N- and C-arms that together grip the DNA. The C-arms of R.NgoAVII, EcoRII, BfiI and plant B3 domains are similar in size, but the R.NgoAVII N-arm which makes the majority of the contacts to the target site is much longer. The overall structures of R.NgoAVII and BfiI are similar; however, whilst BfiI has stand-alone catalytic activity, R.NgoAVII requires an auxiliary cognate N.NgoAVII protein and ATP hydrolysis in order to cleave DNA at the target site. The structures we present will help formulate future experiments to explore the molecular mechanisms of intersubunit crosstalk that control DNA cleavage by R.NgoAVII and related endonucleases. PMID:25429979

Tamulaitiene, Giedre; Silanskas, Arunas; Grazulis, Saulius; Zaremba, Mindaugas; Siksnys, Virginijus

2014-12-16

376

Crystal structure of the R-protein of the multisubunit ATP-dependent restriction endonuclease NgoAVII  

PubMed Central

The restriction endonuclease (REase) NgoAVII is composed of two proteins, R.NgoAVII and N.NgoAVII, and shares features of both Type II restriction enzymes and Type I/III ATP-dependent restriction enzymes (see accompanying paper Zaremba et al., 2014). Here we present crystal structures of the R.NgoAVII apo-protein and the R.NgoAVII C-terminal domain bound to a specific DNA. R.NgoAVII is composed of two domains: an N-terminal nucleolytic PLD domain; and a C-terminal B3-like DNA-binding domain identified previously in BfiI and EcoRII REases, and in plant transcription factors. Structural comparison of the B3-like domains of R.NgoAVII, EcoRII, BfiI and the plant transcription factors revealed a conserved DNA-binding surface comprised of N- and C-arms that together grip the DNA. The C-arms of R.NgoAVII, EcoRII, BfiI and plant B3 domains are similar in size, but the R.NgoAVII N-arm which makes the majority of the contacts to the target site is much longer. The overall structures of R.NgoAVII and BfiI are similar; however, whilst BfiI has stand-alone catalytic activity, R.NgoAVII requires an auxiliary cognate N.NgoAVII protein and ATP hydrolysis in order to cleave DNA at the target site. The structures we present will help formulate future experiments to explore the molecular mechanisms of intersubunit crosstalk that control DNA cleavage by R.NgoAVII and related endonucleases. PMID:25429979

Tamulaitiene, Giedre; Silanskas, Arunas; Grazulis, Saulius; Zaremba, Mindaugas; Siksnys, Virginijus

2014-01-01

377

Ecto-Nucleoside Triphosphate Diphosphohydrolase 2 Modulates Local ATP-Induced Calcium Signaling in Human HaCaT Keratinocytes  

PubMed Central

Keratinocytes are the major building blocks of the human epidermis. In many physiological and pathophysiological conditions, keratinocytes release adenosine triphosphate (ATP) as an autocrine/paracrine mediator that regulates cell proliferation, differentiation, and migration. ATP receptors have been identified in various epidermal cell types; therefore, extracellular ATP homeostasis likely determines its long-term, trophic effects on skin health. We investigated the possibility that human keratinocytes express surface-located enzymes that modulate ATP concentration, as well as the corresponding receptor activation, in the pericellular microenvironment. We observed that the human keratinocyte cell line HaCaT released ATP and hydrolyzed extracellular ATP. Interestingly, ATP hydrolysis resulted in adenosine diphosphate (ADP) accumulation in the extracellular space. Pharmacological inhibition by ARL 67156 or gene silencing of the endogenous ecto-nucleoside triphosphate diphosphohydrolase (NTPDase) isoform 2 resulted in a 25% reduction in both ATP hydrolysis and ADP formation. Using intracellular calcium as a reporter, we found that although NTPDase2 hydrolyzed ATP and generated sustainable ADP levels, only ATP contributed to increased intracellular calcium via P2Y2 receptor activation. Furthermore, knocking down NTPDase2 potentiated the nanomolar ATP-induced intracellular calcium increase, suggesting that NTPDase2 globally attenuates nucleotide concentration in the pericellular microenvironment as well as locally shields receptors in the vicinity from being activated by extracellular ATP. Our findings reveal an important role of human keratinocyte NTPDase2 in modulating nucleotide signaling in the extracellular milieu of human epidermis. PMID:23536768

Ho, Chia-Lin; Yang, Chih-Yung; Lin, Wen-Jie; Lin, Chi-Hung

2013-01-01

378

ATP monitoring technology for microbial growth control in potable water systems  

NASA Astrophysics Data System (ADS)

ATP (Adenosine Triphosphate) is the primary energy transfer molecule present in all living biological cells on Earth. ATP cannot be produced or maintained by anything but a living organism, and as such, its measurement is a direct indication of biological activity. The main advantage of ATP as a biological indicator is the speed of the analysis - from collecting the sample to obtaining the result, only minutes are required. The technology to measure ATP is already widely utilized to verify disinfection efficacy in the food industry and is also commonly applied in industrial water processes such as cooling water systems to monitor microbial growth and biocide applications. Research has indicated that ATP measurement technology can also play a key role in such important industries as potable water distribution and biological wastewater treatment. As will be detailed in this paper, LuminUltra Technologies has developed and applied ATP measurement technologies designed for any water type, and as such can provide a method to rapidly and accurately determine the level of biological activity in drinking water supplies. Because of its speed and specificity to biological activity, ATP measurement can play a key role in defending against failing drinking water quality, including those encountered during routine operation and also bioterrorism.

Whalen, Patrick A.; Whalen, Philip J.; Cairns, James E.

2006-05-01

379

Characterization of a Thermophilic ATP-Dependent DNA Ligase from the Euryarchaeon Pyrococcus horikoshii  

PubMed Central

Archaea encode a DNA ligase composed of a C-terminal catalytic domain typical of ATP-dependent ligases plus an N-terminal domain similar to that found in eukaryotic cellular and poxvirus DNA ligases. All archaeal DNA ligases characterized to date have ATP-dependent adenylyltransferase and nick-joining activities. However, recent reports of dual-specificity ATP/NAD+ ligases in two Thermococcus species and Pyrococcus abyssi and an ATP/ADP ligase in Aeropyrum pernix raise the prospect that certain archaeal enzymes might exemplify an undifferentiated ancestral stage in the evolution of ligase substrate specificity. Here we analyze the biochemical properties of Pyrococcus horikoshii DNA ligase. P. horikoshii ligase catalyzes autoadenylylation and nick sealing in the presence of a divalent cation and ATP; it is unable to utilize NAD+ or ADP to promote ligation in lieu of ATP. P. horikoshii ligase is thermophilic in vitro, with optimal adenylyltransferase activity at 90°C and nick-joining activity at 70 to 90°C. P. horikoshii ligase resembles the ligases of Methanobacterium thermautotrophicum and Sulfolobus shibatae in its strict specificity for ATP. PMID:16199559

Keppetipola, Niroshika; Shuman, Stewart

2005-01-01

380

Ca2+ Entry is Required for Mechanical Stimulation-induced ATP Release from Astrocyte  

PubMed Central

Astrocytes and neurons are inseparable partners in the brain. Neurotransmitters released from neurons activate corresponding G protein-coupled receptors (GPCR) expressed in astrocytes, resulting in release of gliotransmitters such as glutamate, D-serine, and ATP. These gliotransmitters in turn influence neuronal excitability and synaptic activities. Among these gliotransmitters, ATP regulates the level of network excitability and is critically involved in sleep homeostasis and astrocytic Ca2+ oscillations. ATP is known to be released from astrocytes by Ca2+-dependent manner. However, the precise source of Ca2+, whether it is Ca2+ entry from outside of cell or from the intracellular store, is still not clear yet. Here, we performed sniffer patch to detect ATP release from astrocyte by using various stimulation. We found that ATP was not released from astrocyte when Ca2+ was released from intracellular stores by activation of G?q-coupled GPCR including PAR1, P2YR, and B2R. More importantly, mechanical stimulation (MS)-induced ATP release from astrocyte was eliminated when external Ca2+ was omitted. Our results suggest that Ca2+ entry, but not release from intracellular Ca2+ store, is critical for MS-induced ATP release from astrocyte.

Lee, Jaekwang; Chun, Ye-Eun; Han, Kyung-Seok; Lee, Jungmoo; Woo, Dong Ho

2015-01-01

381

Evidence for Ca2+-Regulated ATP Release in Gastrointestinal Stromal Tumors  

PubMed Central

Gastrointestinal stromal tumors (GISTs) are thought to originate from the electrically active pacemaker cells of the gastrointestinal tract. Despite the presence of synaptic-like vesicles and proteins involved in cell secretion it remains unclear whether GIST cells possess regulated release mechanisms. The GIST tumor cell line GIST882 was used as a model cell system, and stimulus-release coupling was investigated by confocal microscopy of cytoplasmic free Ca2+ concentration ([Ca2+]i), flow cytometry, and luminometric measurements of extracellular ATP. We demonstrate that GIST cells have an intact intracellular Ca2+-signaling pathway that regulates ATP release. Cell viability and cell membrane integrity was preserved, excluding ATP leakage due to cell death and suggesting active ATP release. The stimulus-secretion signal transduction is at least partly dependent on Ca2+ influx since exclusion of extracellular Ca2+ diminishes the ATP release. We conclude that measurements of ATP release in GISTs may be a useful tool for dissecting the signal transduction pathway, mapping exocytotic components, and possibly for the development and evaluation of drugs. Additionally, release of ATP from GISTs may have importance for tumor tissue homeostasis and immune surveillance escape. PMID:23499741

Berglund, Erik; Berglund, David; Akcakaya, Pinar; Ghaderi, Mehran; Daré, Elisabetta; Berggren, Per-Olof; Köhler, Martin; Aspinwall, Craig A.; Lui, Weng-Onn; Zedenius, Jan; Larsson, Catharina; Bränström, Robert

2013-01-01

382

Elucidation of spermidine interaction with nucleotide ATP by multiple NMR techniques  

PubMed Central

Interaction of polyamines with nucleotides plays a key role in many biological processes. Here we use multiple NMR techniques to characterize interaction of spermidine with adenosine 5?-triphosphate (ATP). Two-dimensional 1H-15N spectra obtained from gs-HMBC experiments at varied pH show significant shift of N-1 peak around pH 2.0-7.0 range, suggesting that spermidine binds to N-1 site of ATP base. The binding facilitates N-1 deprotonation, shifting its pKa from 4.3 to 3.4. By correlating 15N and 31P chemical shift data, it is clear that spermidine is capable of concurrently binding to ATP base and phosphate sites around pH 4.0-7.0. The self-diffusion constants derived from 1H PFG-diffusion measurements provide evidence that binding of spermidine to ATP is in 1:1 ratio, and pH variations do not induce significant nucleotide self-association in our samples. 31P spectral analysis suggests that at neutral pH, Mg2+ ion competes with spermidine and shows stronger binding to ATP phosphates. From 31P kinetic measurements of myosin catalyzed ATP hydrolysis, it is found that binding of spermidine affects the stability and reactivity of ATP. These NMR results are important for advancing the studies on nucleotide-polyamine interaction and its impact on nucleotide structures and activities under varied conditions. PMID:19960498

Song, Zhiyan; Parker, Kari J.; Enoh, Idorenyin; Zhao, Hua; Olubajo, Olarongbe

2010-01-01

383

Mechanisms of ATP-induced calcium signaling and growth arrest in human prostate cancer cells.  

PubMed

This study investigates the calcium mechanisms involved in growth arrest induced by extracellular ATP in DU-145 androgen-independent human prostate cancer cells. Exposure of DU-145 cells to 100 microM ATP produced an increase in cytoplasmic calcium concentration ([Ca(2+)](i)), due to a mobilization of calcium from the endoplasmic reticulum stores and to subsequent capacitative calcium entry (CCE). We have shown that this [Ca(2+)](i) increase occurs after stimulation by ATP of the phospholipase C (PLC) pathway. For the first time, we have identified the inositol 1,4,5-trisphosphate receptor (IP(3)R) isoforms expressed in this cell line and have demonstrated a participation of protein kinase C in CCE. Using fluorescence imaging, we have shown that a long-term treatment with ATP leads to a decrease in the intraluminal endoplasmic reticulum calcium concentration as well as in the amount of releasable Ca(2+). Modulating extracellular free calcium concentrations indicated that variations in [Ca(2+)](i) did not affect the ATP-induced growth arrest of DU-145 cells. However, treating cells with 1 nM thapsigargin (TG) to deplete intracellular calcium pools prevented the growth arrest induced by ATP. Altogether, these results indicate that growth arrest induced in DU-145 cells by extracellular ATP is not correlated with an increase in [Ca(2+)](i) but rather with a decrease in intracellular calcium pool content. PMID:12767895

Vanoverberghe, K; Mariot, P; Vanden Abeele, F; Delcourt, P; Parys, J B; Prevarskaya, N

2003-07-01

384

Wilson Disease Protein ATP7B Utilizes Lysosomal Exocytosis to Maintain Copper Homeostasis  

PubMed Central

Summary Copper is an essential yet toxic metal and its overload causes Wilson disease, a disorder due to mutations in copper transporter ATP7B. To remove excess copper into the bile, ATP7B traffics toward canalicular area of hepatocytes. However, the trafficking mechanisms of ATP7B remain elusive. Here, we show that, in response to elevated copper, ATP7B moves from the Golgi to lysosomes and imports metal into their lumen. ATP7B enables lysosomes to undergo exocytosis through the interaction with p62 subunit of dynactin that allows lysosome translocation toward the canalicular pole of hepatocytes. Activation of lysosomal exocytosis stimulates copper clearance from the hepatocytes and rescues the most frequent Wilson-disease-causing ATP7B mutant to the appropriate functional site. Our findings indicate that lysosomes serve as an important intermediate in ATP7B trafficking, whereas lysosomal exocytosis operates as an integral process in copper excretion and hence can be targeted for therapeutic approaches to combat Wilson disease. PMID:24909901

Polishchuk, Elena V.; Concilli, Mafalda; Iacobacci, Simona; Chesi, Giancarlo; Pastore, Nunzia; Piccolo, Pasquale; Paladino, Simona; Baldantoni, Daniela; van IJzendoorn, Sven C.D.; Chan, Jefferson; Chang, Christopher J.; Amoresano, Angela; Pane, Francesca; Pucci, Piero; Tarallo, Antonietta; Parenti, Giancarlo; Brunetti-Pierri, Nicola; Settembre, Carmine; Ballabio, Andrea; Polishchuk, Roman S.

2014-01-01

385

Wilson disease protein ATP7B utilizes lysosomal exocytosis to maintain copper homeostasis.  

PubMed

Copper is an essential yet toxic metal and its overload causes Wilson disease, a disorder due to mutations in copper transporter ATP7B. To remove excess copper into the bile, ATP7B traffics toward canalicular area of hepatocytes. However, the trafficking mechanisms of ATP7B remain elusive. Here, we show that, in response to elevated copper, ATP7B moves from the Golgi to lysosomes and imports metal into their lumen. ATP7B enables lysosomes to undergo exocytosis through the interaction with p62 subunit of dynactin that allows lysosome translocation toward the canalicular pole of hepatocytes. Activation of lysosomal exocytosis stimulates copper clearance from the hepatocytes and rescues the most frequent Wilson-disease-causing ATP7B mutant to the appropriate functional site. Our findings indicate that lysosomes serve as an important intermediate in ATP7B trafficking, whereas lysosomal exocytosis operates as an integral process in copper excretion and hence can be targeted for therapeutic approaches to combat Wilson disease. PMID:24909901

Polishchuk, Elena V; Concilli, Mafalda; Iacobacci, Simona; Chesi, Giancarlo; Pastore, Nunzia; Piccolo, Pasquale; Paladino, Simona; Baldantoni, Daniela; van IJzendoorn, Sven C D; Chan, Jefferson; Chang, Christopher J; Amoresano, Angela; Pane, Francesca; Pucci, Piero; Tarallo, Antonietta; Parenti, Giancarlo; Brunetti-Pierri, Nicola; Settembre, Carmine; Ballabio, Andrea; Polishchuk, Roman S

2014-06-23

386

Mutations in the ATP13A2 Gene and Parkinsonism: A Preliminary Review  

PubMed Central

Parkinson's disease (PD) is a major neurodegenerative disorder for which the etiology and pathogenesis remain as elusive as for Alzheimer's disease. PD appears to be caused by genetic and environmental factors, and pedigree and cohort studies have identified numerous susceptibility genes and loci related to PD. Autosomal recessive mutations in the genes Parkin, Pink1, DJ-1, ATP13A2, PLA2G6, and FBXO7 have been linked to PD susceptibility. Such mutations in ATP13A2, also named PARK9, were first identified in 2006 in a Chilean family and are associated with a juvenile-onset, levodopa-responsive type of Parkinsonism called Kufor-Rakeb syndrome (KRS). KRS involves pyramidal degeneration, supranuclear palsy, and cognitive impairment. Here we review current knowledge about the ATP13A2 gene, clinical characteristics of patients with PD-associated ATP13A2 mutations, and models of how the ATP13A2 protein may help prevent neurodegeneration by inhibiting ?-synuclein aggregation and supporting normal lysosomal and mitochondrial function. We also discuss another ATP13A2 mutation that is associated with the family of neurodegenerative disorders called neuronal ceroid lipofuscinoses (NCLs), and we propose a single pathway whereby ATP13A2 mutations may contribute to NCLs and Parkinsonism. Finally, we highlight how studies of mutations in this gene may provide new insights into PD pathogenesis and identify potential therapeutic targets. PMID:25197640

Yang, Xinglong; Xu, Yanming

2014-01-01

387

Regulation of human serine racemase activity and dynamics by halides, ATP and malonate.  

PubMed

D-Serine is a non-proteinogenic amino acid that acts as a co-agonist of the NMDA receptors in the central nervous system. D-Serine is produced by human serine racemase (hSR), a homodimeric pyridoxal 5'-phosphate (PLP)-dependent enzyme that also catalyzes the physiologically relevant ?-elimination of both L- and D-serine to pyruvate and ammonia. After improving the protein purification yield and stability, which had so far limited the biochemical characterization of hSR, we found that the catalytic activity is affected by halides, in the order fluoride > chloride > bromide. On the contrary, iodide elicited a complete inhibition, accompanied by a modulation of the tautomeric equilibrium of the internal aldimine. We also investigated the reciprocal effects of ATP and malonate, an inhibitor that reversibly binds at the active site, 20 Å away from the ATP-binding site. ATP increased ninefold the affinity of hSR for malonate and malonate increased 100-fold that of ATP, confirming an allosteric interaction between the two binding sites. To further investigate this allosteric communication, we probed the active site accessibility by quenching of the coenzyme fluorescence in the absence and presence of ATP. We found that ATP stabilizes a closed conformation of the external aldimine Schiff base, suggesting a possible mechanism for ATP-induced hSR activation. PMID:25331425

Marchetti, Marialaura; Bruno, Stefano; Campanini, Barbara; Bettati, Stefano; Peracchi, Alessio; Mozzarelli, Andrea

2015-01-01

388

Involvement of anion channels in mediating elicitor-induced ATP efflux in Salvia miltiorrhiza hairy roots.  

PubMed

This study examines the roles of anion channels and ATP binding cassette (ABC) protein transporters in mediating elicitor-induced ATP release in Salvia miltiorrhiza hairy root cultures. The elicitor-induced ATP release was effectively blocked by two putative membrane anion channel blockers, niflumic acid and Zn(2+), but not by a specific Cl(-) channel blocker, phenylanthranilic acid. The elicitor-induced ATP release was also significantly suppressed by two ABC inhibitors, glibenclamide and ethacrynic acid. Notable ATP release from the hairy roots was also induced by verapamil (2mM), an ABC activator in animal cells. The verapamil-induced ATP release was effectively blocked by niflumic acid, but only slightly inhibited by the ABC inhibitors. Another notable effect of verapamil was the induction of exocytosis, the secretion of vesicle-like particles to the root surface. The verapamil-induced exocytosis was not inhibited by nifulumic acid and YE did not induce the exocytosis. Overall, the results suggest a significant role of anion channels, a possible involvement of ABC proteins and no significant involvement of exocytosis in mediating the ATP efflux in hairy root cells. PMID:20813428

Wu, Shu-Jing; Siu, Ka-Chai; Wu, Jian-Yong

2011-01-15

389

ATP-dependent bile-salt transport in canalicular rat liver plasma-membrane vesicles.  

PubMed Central

The present study identifies and characterizes a novel ATP-dependent bile-salt transport system in isolated canalicular rat liver plasma-membrane (cLPM) vesicles. ATP (1-5 mM) stimulated taurocholate uptake into cLPM vesicles between 6- and 8-fold above equilibrium uptake values (overshoot) and above values for incubations in the absence of ATP. The ATP-dependent portion of taurocholate uptake was 2-fold higher in the presence of equilibrated KNO3 as compared with potassium gluconate, indicating that the stimulatory effect of ATP was not due to the generation of an intravesicular positive membrane potential. Saturation kinetics revealed a very high affinity (Km approximately 2.1 microM) of the system for taurocholate. The system could only minimally be stimulated by nucleotides other than ATP. Furthermore, it was preferentially inhibited by conjugated univalent bile salts. Further strong inhibitory effects were observed with valinomycin, oligomycin, 4,4'-di-isothiocyano-2,2'-stilbene disulphonate, sulphobromophthalein, leukotriene C4 and N-ethylmaleimide, whereas nigericin, vanadate, GSH, GSSG and daunomycin exerted only weak inhibitory effects or none at all. These results indicate the presence of a high-affinity primary ATP-dependent bile-salt transport system in cLPM vesicles. This transport system might be regulated in vivo by the number of carriers present at the perspective transport site(s), which, in addition to the canalicular membrane, might also include pericanalicular membrane vesicles. PMID:1599411

Stieger, B; O'Neill, B; Meier, P J

1992-01-01

390

Multiple ATP-hydrolyzing sites that potentially function in cytoplasmic dynein  

PubMed Central

Cytoplasmic dynein is a minus-end-directed microtubule motor involved in numerous essential processes within eukaryotic cells, such as nuclear segregation and trafficking of intracellular particles. The motor domain of the dynein heavy chain comprises six tandemly linked AAA (ATPase associated with diverse cellular activities) modules (AAA1–AAA6). The first four modules include nucleotide-binding sites (Walker A or P-loop motifs), and each of the four sites appears to bind ATP. However, the role and the function of each binding site are unknown. Especially, the question of which P-loops are ATP-hydrolyzing sites has not been answered, because it is difficult to measure the ATPase activity of each P-loop. Here, we purified several truncated Saccharomyces cerevisiae cytoplasmic dynein fragments and their mutants expressed in Escherichia coli and then measured their ATPase activities. Our results suggest that there are multiple ATP-binding sites that have abilities to hydrolyze ATP in cytoplasmic dynein. Furthermore, a single AAA module is insufficient for ATP hydrolysis, and the adjacent module facing the ATP-binding site is necessary for ATP-hydrolyzing activity. PMID:15326307

Takahashi, Yoshinori; Edamatsu, Masaki; Toyoshima, Yoko Y.

2004-01-01

391

Multiple ATP-hydrolyzing sites that potentially function in cytoplasmic dynein.  

PubMed

Cytoplasmic dynein is a minus-end-directed microtubule motor involved in numerous essential processes within eukaryotic cells, such as nuclear segregation and trafficking of intracellular particles. The motor domain of the dynein heavy chain comprises six tandemly linked AAA (ATPase associated with diverse cellular activities) modules (AAA1-AAA6). The first four modules include nucleotide-binding sites (Walker A or P-loop motifs), and each of the four sites appears to bind ATP. However, the role and the function of each binding site are unknown. Especially, the question of which P-loops are ATP-hydrolyzing sites has not been answered, because it is difficult to measure the ATPase activity of each P-loop. Here, we purified several truncated Saccharomyces cerevisiae cytoplasmic dynein fragments and their mutants expressed in Escherichia coli and then measured their ATPase activities. Our results suggest that there are multiple ATP-binding sites that have abilities to hydrolyze ATP in cytoplasmic dynein. Furthermore, a single AAA module is insufficient for ATP hydrolysis, and the adjacent module facing the ATP-binding site is necessary for ATP-hydrolyzing activity. PMID:15326307

Takahashi, Yoshinori; Edamatsu, Masaki; Toyoshima, Yoko Y

2004-08-31

392

Impairment of vesicular ATP release affects glucose metabolism and increases insulin sensitivity  

PubMed Central

Neuroendocrine cells store ATP in secretory granules and release it along with hormones that may trigger a variety of cellular responses in a process called purinergic chemical transmission. Although the vesicular nucleotide transporter (VNUT) has been shown to be involved in vesicular storage and release of ATP, its physiological relevance in vivo is far less well understood. In Vnut knockout (Vnut?/?) mice, we found that the loss of functional VNUT in adrenal chromaffin granules and insulin granules in the islets of Langerhans led to several significant effects. Vesicular ATP accumulation and depolarization-dependent ATP release were absent in the chromaffin granules of Vnut?/? mice. Glucose-responsive ATP release was also absent in pancreatic ?-cells in Vnut?/? mice, while glucose-responsive insulin secretion was enhanced to a greater extent than that in wild-type tissue. Vnut?/? mice exhibited improved glucose tolerance and low blood glucose upon fasting due to increased insulin sensitivity. These results demonstrated an essential role of VNUT in vesicular storage and release of ATP in neuroendocrine cells in vivo and suggest that vesicular ATP and/or its degradation products act as feedback regulators in catecholamine and insulin secretion, thereby regulating blood glucose homeostasis. PMID:25331291

Sakamoto, Shohei; Miyaji, Takaaki; Hiasa, Miki; Ichikawa, Reiko; Uematsu, Akira; Iwatsuki, Ken; Shibata, Atsushi; Uneyama, Hisayuki; Takayanagi, Ryoichi; Yamamoto, Akitsugu; Omote, Hiroshi; Nomura, Masatoshi; Moriyama, Yoshinori

2014-01-01

393

Ca(2+) Entry is Required for Mechanical Stimulation-induced ATP Release from Astrocyte.  

PubMed

Astrocytes and neurons are inseparable partners in the brain. Neurotransmitters released from neurons activate corresponding G protein-coupled receptors (GPCR) expressed in astrocytes, resulting in release of gliotransmitters such as glutamate, D-serine, and ATP. These gliotransmitters in turn influence neuronal excitability and synaptic activities. Among these gliotransmitters, ATP regulates the level of network excitability and is critically involved in sleep homeostasis and astrocytic Ca(2+) oscillations. ATP is known to be released from astrocytes by Ca(2+)-dependent manner. However, the precise source of Ca(2+), whether it is Ca(2+) entry from outside of cell or from the intracellular store, is still not clear yet. Here, we performed sniffer patch to detect ATP release from astrocyte by using various stimulation. We found that ATP was not released from astrocyte when Ca(2+) was released from intracellular stores by activation of G?q-coupled GPCR including PAR1, P2YR, and B2R. More importantly, mechanical stimulation (MS)-induced ATP release from astrocyte was eliminated when external Ca(2+) was omitted. Our results suggest that Ca(2+) entry, but not release from intracellular Ca(2+) store, is critical for MS-induced ATP release from astrocyte. PMID:25792866

Lee, Jaekwang; Chun, Ye-Eun; Han, Kyung-Seok; Lee, Jungmoo; Woo, Dong Ho; Lee, C Justin

2015-03-01

394

ATP microelectrode biosensor for stable long-term in vitro monitoring from gastrointestinal tissue.  

PubMed

We have developed a stable and selective ATP biosensor for long-term in vitro tissue monitoring. The electrode was fabricated by entrapping glucose oxidase (GOx) and hexokinase (HEX) in a poly-phenol film on a Pt microelectrode. The biosensor was stable to a fixed concentration of glucose for over 20 min and had a limit of detection of 9.9 ± 3.2 nM, with a sensitivity of 45.8 ± 1.22 pA ?M(-1). Most significantly of all, the response on the ATP biosensor did not alter in the presence of 1mM ascorbic acid, 5 ?M dopamine, 5 ?M serotonin, 5 ?M ADP and 5 ?M AMP. The ATP biosensor was also shown to have excellent stability over 7 days, and showed only a 23.92 ± 3.55% loss in sensitivity. The ATP biosensor was utilised for the in vitro detection of ATP from gastrointestinal tissue. The ATP biosensor response was stable for 5h during in vitro recordings from ileum tissue. ATP release was shown to be greater from the mucosal surface in the ileum compared to the colon. PMID:21163639

Patel, Bhavik Anil; Rogers, Michelle; Wieder, Talia; O'Hare, Danny; Boutelle, Martyn G

2011-02-15

395

Liver ATP Synthesis Is Lower and Relates to Insulin Sensitivity in Patients With Type 2 Diabetes  

PubMed Central

OBJECTIVE Steatosis associates with insulin resistance and may even predict type 2 diabetes and cardiovascular complications. Because muscular insulin resistance relates to myocellular fat deposition and disturbed energy metabolism, we hypothesized that reduced hepatic ATP turnover (fATP) underlies insulin resistance and elevated hepatocellular lipid (HCL) contents. RESEARCH DESIGN AND METHODS We measured hepatic fATP using 31P magnetic resonance spectroscopy in patients with type 2 diabetes and age- and body mass–matched controls. Peripheral (M and M/I) and hepatic (suppression of endogenous glucose production) insulin sensitivity were assessed with euglycemic-hyperinsulinemic clamps. RESULTS Diabetic individuals had 29% and 28% lower peripheral and hepatic insulin sensitivity as well as 42% reduced fATP than controls. After adjusting for HCL, fATP correlated positively with peripheral and hepatic insulin sensitivity but negatively with waist circumference, BMI, and fasting plasma glucose. Multiple regression analysis identified waist circumference as an independent predictor of fATP and inorganic phosphate (PI) concentrations, explaining 65% (P = 0.001) and 56% (P = 0.003) of the variations. Hepatocellular PI primarily determined the alterations in fATP. CONCLUSIONS In patients with type 2 diabetes, insulin resistance relates to perturbed hepatic energy metabolism, which is at least partly accounted for by fat depots. PMID:21216854

Schmid, Albrecht Ingo; Szendroedi, Julia; Chmelik, Marek; Krššák, Martin; Moser, Ewald; Roden, Michael

2011-01-01

396

Molecular mechanism of ATP binding and ion channel activation in P2X receptors  

SciTech Connect

P2X receptors are trimeric ATP-activated ion channels permeable to Na{sup +}, K{sup +} and Ca{sup 2+}. The seven P2X receptor subtypes are implicated in physiological processes that include modulation of synaptic transmission, contraction of smooth muscle, secretion of chemical transmitters and regulation of immune responses. Despite the importance of P2X receptors in cellular physiology, the three-dimensional composition of the ATP-binding site, the structural mechanism of ATP-dependent ion channel gating and the architecture of the open ion channel pore are unknown. Here we report the crystal structure of the zebrafish P2X4 receptor in complex with ATP and a new structure of the apo receptor. The agonist-bound structure reveals a previously unseen ATP-binding motif and an open ion channel pore. ATP binding induces cleft closure of the nucleotide-binding pocket, flexing of the lower body {beta}-sheet and a radial expansion of the extracellular vestibule. The structural widening of the extracellular vestibule is directly coupled to the opening of the ion channel pore by way of an iris-like expansion of the transmembrane helices. The structural delineation of the ATP-binding site and the ion channel pore, together with the conformational changes associated with ion channel gating, will stimulate development of new pharmacological agents.

Hattori, Motoyuki; Gouaux, Eric (Oregon HSU)

2012-10-24

397

ATP and other adenine compounds increase mechanical activity and inositol trisphosphate production in rat heart.  

PubMed Central

1. The effects of adenosine 5'-triphosphate (ATP) and other adenine compounds were examined on rat papillary and right ventricular muscles in the presence of 10 microM-propranolol, 10 microM-atropine and 0.1 microM-prazosin or 10 microM-phentolamine. 2. Adenosine, adenosine 5'-monophosphate (AMP), adenosine 5'-diphosphate (ADP), ATP and alpha,beta-methylene ATP (APCPP) produced small positive inotropic effects, sometimes preceded by transient negative effects. 3. 8-Phenyltheophylline (8-PT), a P1-purinoceptor antagonist antagonized the negative effects and increased the positive inotropy induced by ATP and adenosine. 4. In the presence of APCPP, a P2-purinergic agonist, ATP had only negative inotropic effects. 5. Adenosine and ATP increased inositol 1, 4, 5- and inositol 1, 3, 4-trisphosphate as well as inositol mono- and bisphosphate formation. Maximal effects were obtained at concentrations of 0.5 mM. 6. APCPP increased inositol phosphate formation while 8-PT did not prevent the effects of adenosine and ATP. 7. It is suggested that P2-purinoceptor activation induces both a positive inotropy and an increase in inositol-lipid metabolism in rat ventricular muscles. PMID:3262739

Legssyer, A; Poggioli, J; Renard, D; Vassort, G

1988-01-01

398

Control of a Salmonella Virulence Locus by an ATP-Sensing Leader mRNA  

PubMed Central

The facultative intracellular pathogen Salmonella enterica resides within a membrane-bound compartment inside macrophages 1. This compartment must be acidified for Salmonella to survive within macrophages 2, possibly because acid pH promotes expression of Salmonella virulence proteins 3,4. We reasoned that Salmonella may sense its surroundings have turned acidic not only upon protonation of the extracytoplasmic domain of a protein sensor 5 but also by an increase in cytosolic ATP levels because conditions that enhance the proton gradient across the bacterial inner membrane stimulate ATP synthesis 6,7. We now report that an increase in cytosolic ATP promotes transcription of the coding region for the virulence gene mgtC, which is the most highly-induced horizontally-acquired gene when Salmonella is inside macrophages 8. This transcript was induced both upon media acidification as well as by physiological conditions that increase ATP levels independently of acidification. ATP is sensed via the coupling/uncoupling of transcription of the unusually long mgtC leader mRNA and translation of a short open reading frame located in this region. A mutation in the mgtC leader mRNA that eliminated the response to ATP hindered mgtC expression inside macrophages and attenuated Salmonella virulence in mice. Our results define a singular example of an ATP-sensing leader mRNA. Moreover, they indicate that pathogens can interpret extracellular cues by the impact they have on cellular metabolites. PMID:22699622

Lee, Eun-Jin; Groisman, Eduardo A.

2013-01-01

399

Type III restriction-modification enzymes: a historical perspective.  

PubMed

Restriction endonucleases interact with DNA at specific sites leading to cleavage of DNA. Bacterial DNA is protected from restriction endonuclease cleavage by modifying the DNA using a DNA methyltransferase. Based on their molecular structure, sequence recognition, cleavage position and cofactor requirements, restriction-modification (R-M) systems are classified into four groups. Type III R-M enzymes need to interact with two separate unmethylated DNA sequences in inversely repeated head-to-head orientations for efficient cleavage to occur at a defined location (25-27 bp downstream of one of the recognition sites). Like the Type I R-M enzymes, Type III R-M enzymes possess a sequence-specific ATPase activity for DNA cleavage. ATP hydrolysis is required for the long-distance communication between the sites before cleavage. Different models, based on 1D diffusion and/or 3D-DNA looping, exist to explain how the long-distance interaction between the two recognition sites takes place. Type III R-M systems are found in most sequenced bacteria. Genome sequencing of many pathogenic bacteria also shows the presence of a number of phase-variable Type III R-M systems, which play a role in virulence. A growing number of these enzymes are being subjected to biochemical and genetic studies, which, when combined with ongoing structural analyses, promise to provide details for mechanisms of DNA recognition and catalysis. PMID:23863841

Rao, Desirazu N; Dryden, David T F; Bheemanaik, Shivakumara

2014-01-01

400

Mitochondrial inefficiencies and anoxic ATP hydrolysis capacities in diabetic rat heart.  

PubMed

As ~80% of diabetic patients die from heart failure, an understanding of diabetic cardiomyopathy is crucial. Mitochondria occupy 35-40% of the mammalian cardiomyocyte volume and supply 95% of the heart's ATP, and diabetic heart mitochondria show impaired structure, arrangement, and function. We predict that bioenergetic inefficiencies are present in diabetic heart mitochondria; therefore, we explored mitochondrial proton and electron handling by linking oxygen flux to steady-state ATP synthesis, reactive oxygen species (ROS) production, and mitochondrial membrane potential (??) within rat heart tissues. Sprague-Dawley rats were injected with streptozotocin (STZ, 55 mg/kg) to induce type 1 diabetes or an equivalent volume of saline (control, n = 12) and fed standard rat chow for 8 wk. By coupling high-resolution respirometers with purpose-built fluorometers, we followed Magnesium Green (ATP synthesis), Amplex UltraRed (ROS production), and safranin-O (??). Relative to control rats, the mass-specific respiration of STZ-diabetic hearts was depressed in oxidative phosphorylation (OXPHOS) states. Steady-state ATP synthesis capacity was almost one-third lower in STZ-diabetic heart, which, relative to oxygen flux, equates to an estimated 12% depression in OXPHOS efficiency. However, with anoxic transition, STZ-diabetic and control heart tissues showed similar ATP hydrolysis capacities through reversal of the F1F0-ATP synthase. STZ-diabetic cardiac mitochondria also produced more net ROS relative to oxygen flux (ROS/O) in OXPHOS. While ?? did not differ between groups, the time to develop ?? with the onset of OXPHOS was protracted in STZ-diabetic mitochondria. ROS/O is higher in lifelike OXPHOS states, and potential delays in the time to develop ?? may delay ATP synthesis with interbeat fluctuations in ADP concentrations. Whereas diabetic cardiac mitochondria produce less ATP in normoxia, they consume as much ATP in anoxic infarct-like states. PMID:24920675

Pham, Toan; Loiselle, Denis; Power, Amelia; Hickey, Anthony J R

2014-09-15

401

Cystic Fibrosis Transmembrane Conductance Regulator–associated ATP Release Is Controlled by a Chloride Sensor  

PubMed Central

The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel that is defective in cystic fibrosis, and has also been closely associated with ATP permeability in cells. Using a Xenopus oocyte cRNA expression system, we have evaluated the molecular mechanisms that control CFTR-modulated ATP release. CFTR-modulated ATP release was dependent on both cAMP activation and a gradient change in the extracellular chloride concentration. Activation of ATP release occurred within a narrow concentration range of external Cl? that was similar to that reported in airway surface fluid. Mutagenesis of CFTR demonstrated that Cl? conductance and ATP release regulatory properties could be dissociated to different regions of the CFTR protein. Despite the lack of a need for Cl? conductance through CFTR to modulate ATP release, alterations in channel pore residues R347 and R334 caused changes in the relative ability of different halides to activate ATP efflux (wtCFTR, Cl >> Br; R347P, Cl >> Br; R347E, Br >> Cl; R334W, Cl = Br). We hypothesize that residues R347 and R334 may contribute a Cl? binding site within the CFTR channel pore that is necessary for activation of ATP efflux in response to increases of extracellular Cl?. In summary, these findings suggest a novel chloride sensor mechanism by which CFTR is capable of responding to changes in the extracellular chloride concentration by modulating the activity of an unidentified ATP efflux pathway. This pathway may play an important role in maintaining fluid and electrolyte balance in the airway through purinergic regulation of epithelial cells. Insight into these molecular mechanisms enhances our understanding of pathogenesis in the cystic fibrosis lung. PMID:9813087

Jiang, Qinshi; Mak, Daniel; Devidas, Sreenivas; Schwiebert, Erik M.; Bragin, Alvina; Zhang, Yulong; Skach, William R.; Guggino, William B.; Foskett, J. Kevin; Engelhardt, John F.

1998-01-01

402

Inhibition of store-operated Ca2+ entry by extracellular ATP in rat brown adipocytes  

PubMed Central

Modulation of intracellular free Ca2+ concentration ([Ca2+]i) by extracellular ATP was investigated in cultured adult rat brown adipocytes using the fluorescent Ca2+ indicator fura-2.Bath application of ATP in micromolar concentrations caused a large increase in [Ca2+]i in cells previously stimulated with noradrenaline. This ATP-induced [Ca2+]i increase exhibited a monotonic decline to near the resting levels within approximately 2 min, even in the continued presence of the agonist.The magnitude and time course of the [Ca2+]i increase in response to ATP were not significantly affected by removal of extracellular Ca2+, suggesting that a mobilization of intracellular Ca2+ primarily contributes to the increase.The [Ca2+]i increase in response to ATP was sensitive to inhibition by suramin, suggesting the involvement of P2 purinoceptors in the response.Thapsigargin (100 nm) evoked a gradual and irreversible increase in [Ca2+]i which was entirely dependent upon extracellular Ca2+, providing functional evidence for the expression of store-operated Ca2+ entry in these brown adipocytes.Extracellular ATP at a concentration of 10 ?m depressed this thapsigargin (100 nm)-induced [Ca2+]i increase by 92 ± 3 % (n= 8 cells), strongly suggesting that ATP inhibits an influx of Ca2+ across the plasma membrane through the store-operated pathway. Bath application of phorbol 12-myristate 13-acetate (PMA, 5 ?m) did not affect the thapsigargin-induced [Ca2+]i increase, indicating that the inhibitory action of ATP is not mediated by activation of protein kinase C (PKC).These results indicate that extracellular ATP not only mobilizes Ca2+ from the intracellular stores but also exerts a potent inhibitory effect on the store-operated Ca2+ entry process in adult rat brown adipocytes. PMID:10601492

Omatsu-Kanbe, Mariko; Matsuura, Hiroshi

1999-01-01

403

Imaging and characterization of stretch-induced ATP release from alveolar A549 cells  

PubMed Central

Mechano-transduction at cellular and tissue levels often involves ATP release and activation of the purinergic signalling cascade. In the lungs, stretch is an important physical stimulus but its impact on ATP release, the underlying release mechanisms and transduction pathways are poorly understood. Here, we investigated the effect of unidirectional stretch on ATP release from human alveolar A549 cells by real-time luciferin–luciferase bioluminescence imaging coupled with simultaneous infrared imaging, to monitor the extent of cell stretch and to identify ATP releasing cells. In subconfluent (<90%) cell cultures, single 1 s stretch (10–40%)-induced transient ATP release from a small fraction (?1.5%) of cells that grew in number dose-dependently with increasing extent of stretch. ATP concentration in the proximity (?150 ?m) of releasing cells often exceeded 10 ?m, sufficient for autocrine/paracrine purinoreceptor stimulation of neighbouring cells. ATP release responses were insensitive to the putative ATP channel blockers carbenoxolone and 5-nitro-2-(3-phenylpropyl-amino) benzoic acid, but were inhibited by N-ethylmaleimide and bafilomycin. In confluent cell cultures, the maximal fraction of responding cells dropped to <0.2%, but was enhanced several-fold in the wound/scratch area after it was repopulated by new cells during the healing process. Fluo8 fluorescence experiments revealed two types of stretch-induced intracellular Ca2+ responses, rapid sustained Ca2+ elevations in a limited number of cells and delayed secondary responses in neighbouring cells, seen as Ca2+ waves whose propagation was consistent with extracellular diffusion of released ATP. Our experiments revealed that a single >10% stretch was sufficient to initiate intercellular purinergic signalling in alveolar cells, which may contribute to the regulation of surfactant secretion and wound healing. PMID:23247110

Grygorczyk, Ryszard; Furuya, Kishio; Sokabe, Masahiro

2013-01-01

404

Unexpected role of the copper transporter ATP7A in PDGF-induced vascular smooth  

SciTech Connect

Copper, an essential nutrient, has been implicated in vascular remodeling and atherosclerosis with unknown mechanism. Bioavailability of intracellular copper is regulated not only by the copper importer CTR1 (copper transporter 1) but also by the copper exporter ATP7A (Menkes ATPase), whose function is achieved through copper-dependent translocation from trans-Golgi network (TGN). Platelet-derived growth factor (PDGF) promotes vascular smooth muscle cell (VSMC) migration, a key component of neointimal formation. To determine the role of copper transporter ATP7A in PDGF-induced VSMC migration. Depletion of ATP7A inhibited VSMC migration in response to PDGF or wound scratch in a CTR1/copper-dependent manner. PDGF stimulation promoted ATP7A translocation from the TGN to lipid rafts, which localized at the leading edge, where it colocalized with PDGF receptor and Rac1, in migrating VSMCs. Mechanistically, ATP7A small interfering RNA or CTR small interfering RNA prevented PDGF-induced Rac1 translocation to the leading edge, thereby inhibiting lamellipodia formation. In addition, ATP7A depletion prevented a PDGF-induced decrease in copper level and secretory copper enzyme precursor prolysyl oxidase (Pro-LOX) in lipid raft fraction, as well as PDGF-induced increase in LOX activity. In vivo, ATP7A expression was markedly increased and copper accumulation was observed by synchrotron-based x-ray fluorescence microscopy at neointimal VSMCs in wire injury model. These findings suggest that ATP7A plays an important role in copper-dependent PDGF-stimulated VSMC migration via recruiting Rac1 to lipid rafts at the leading edge, as well as regulating LOX activity. This may contribute to neointimal formation after vascular injury. Our findings provide insight into ATP7A as a novel therapeutic target for vascular remodeling and atherosclerosis.

Ashino, T.; Varadarajan, S.; Urao, N.; Oshikawa, J.; Chen, G. -F.; Wang, H.; Huo, Y.; Finney, L.; Vogt, S.; McKinney, R. D.; Maryon, E. B.; Kaplan, J. H.; Ushio-Fukai, M.; Fukai, T. (Biosciences Division); ( XSD); ( PSC-USR); (Univ. of Illinois at Chicago); (Univ. of Minnesota)

2010-09-09

405

ATP release and Ca2+ signalling by human bronchial epithelial cells following Alternaria aeroallergen exposure  

PubMed Central

Exposure of human bronchial epithelial (HBE) cells from normal and asthmatic subjects to extracts from Alternaria alternata evoked a rapid and sustained release of ATP with greater efficacy observed in epithelial cells from asthmatic patients. Previously, Alternaria allergens were shown to produce a sustained increase in intracellular Ca2+ concentration ([Ca2+]i) that was dependent on the coordinated activation of specific purinergic receptor (P2Y2 and P2X7) subtypes. In the present study, pretreatment with a cell-permeable Ca2+-chelating compound (BAPTA-AM) significantly inhibited ATP release, indicating dependency on [Ca2+]i. Alternaria-evoked ATP release exhibited a greater peak response and a slightly lower EC50 value in cells obtained from asthmatic donors compared to normal control cells. Furthermore, the maximum increase in [Ca2+]i resulting from Alternaria treatment was greater in cells from asthmatic patients compared to normal subjects. The vesicle transport inhibitor brefeldin A and BAPTA-AM significantly blocked Alternaria-stimulated incorporation of fluorescent lipid (FM1-43)-labelled vesicles into the plasma membrane and ATP release. In addition, inhibiting uptake of ATP into exocytotic vesicles with bafilomycin also reduced ATP release comparable to the effects of brefeldin A and BAPTA-AM. These results indicate that an important mechanism for Alternaria-induced ATP release is Ca2+ dependent and involves exocytosis of ATP. Serine and cysteine protease inhibitors also reduced Alternaria-induced ATP release; however, the sustained increase in [Ca2+]i typically observed following Alternaria exposure appeared to be independent of protease-activated receptor (PAR2) stimulation. PMID:23858006

O'Grady, Scott M; Patil, Nandadavi; Melkamu, Tamene; Maniak, Peter J; Lancto, Cheryl; Kita, Hirohito

2013-01-01

406

ATP7A transgenic and nontransgenic mice are resistant to high copper exposure.  

PubMed

The protein affected in Menkes disease, ATP7A, is a copper (Cu)-transporting P-type ATPase that plays an important role in Cu homeostasis, but the full extent of this role has not been defined at a systemic level. Transgenic mice that overexpress the human ATP7A from the chicken beta-actin composite promoter (CAG) were used to further investigate the physiological function of ATP7A. Overexpression of ATP7A in the mice caused disturbances in Cu homeostasis, with depletion of Cu in some tissues, especially the heart. To investigate the effect of overexpression of ATP7A when dietary Cu intake was markedly increased, normal and transgenic mice were exposed to drinking water containing 300 mg/L of Cu as Cu acetate for 3 mo. Cu exposure resulted in partial restoration of heart Cu concentrations in male transgenic mice. Despite the extended period of Cu exposure, Cu concentrations in the liver remained relatively unaffected, with a significant increase in male nontransgenic mice. Liver pathology was unremarkable except for small areas of fibrosis that were detected only in livers of the Cu-exposed transgenic mice. Intracellular localization of ATP7A in various tissues was not affected by Cu exposure. Plasma Cu concentration and ceruloplasmin oxidase activity were reduced in both Cu-exposed transgenic and nontransgenic mice. The expression levels of other candidate Cu homeostatic proteins, endogenous Atp7b, ceruloplasmin, Ctr1, and transgenic ATP7A were not altered significantly by Cu exposure. Overall, mice are remarkably resistant to high Cu loads and the overexpression of ATP7A has only moderate effects on the response to Cu exposure. PMID:18356322

Ke, Bi-Xia; Llanos, Roxana M; Mercer, Julian F B

2008-04-01

407

The role of intracellular pH in cell growth arrest induced by ATP.  

PubMed

In this study, we investigated ionic mechanisms involved in growth arrest induced by extracellular ATP in androgen-independent prostate cancer cells. Extracellular ATP reversibly induced a rapid and sustained intracellular pH (pH(i)) decrease from 7.41 to 7.11. Inhibition of Ca(2+) influx, lowering extracellular Ca(2+), and buffering cytoplasmic Ca(2+) inhibited ATP-induced acidification, thereby demonstrating that acidification is a consequence of Ca(2+) entry. We show that ATP induced reuptake of Ca(2+) by the mitochondria and a transient depolarization of the inner mitochondrial membrane. ATP-induced acidification was reduced after the dissipation of the mitochondrial proton gradient by rotenone and carbonyl cyanide p-trifluoromethoxyphenylhydrazone, after inhibition of Ca(2+) uptake into the mitochondria by ruthenium red, and after inhibition of the F(0)F(1)-ATPase with oligomycin. ATP-induced acidification was not induced by either stimulation of the Cl(-)/HCO(3)(-) exchanger or inhibition of the Na(+)/H(+) exchanger. In addition, intracellular acidification, induced by an ammonium prepulse method, reduced the amount of releasable Ca(2+) from the endoplasmic reticulum, assessed by measuring change in cytosolic Ca(2+) induced by thapsigargin or ATP in a Ca(2+)-free medium. This latter finding reveals cross talk between pH(i) and Ca(2+) homeostasis in which the Ca(2+)-induced intracellular acidification can in turn regulate the amount of Ca(2+) that can be released from the endoplasmic reticulum. Furthermore, pH(i) decrease was capable of reducing cell growth. Taken together, our results suggest that ATP-induced acidification in DU-145 cells results from specific effect of mitochondrial function and is one of the major mechanisms leading to growth arrest induced by ATP. PMID:15355852

Humez, Sandrine; Monet, Michaël; van Coppenolle, Fabien; Delcourt, Philippe; Prevarskaya, Natalia

2004-12-01

408

Defining the Role of ATP Hydrolysis in Mitotic Segregation of Bacterial Plasmids  

PubMed Central

Hydrolysis of ATP by partition ATPases, although considered a key step in the segregation mechanism that assures stable inheritance of plasmids, is intrinsically very weak. The cognate centromere-binding protein (CBP), together with DNA, stimulates the ATPase to hydrolyse ATP and to undertake the relocation that incites plasmid movement, apparently confirming the need for hydrolysis in partition. However, ATP-binding alone changes ATPase conformation and properties, making it difficult to rigorously distinguish the substrate and cofactor roles of ATP in vivo. We had shown that mutation of arginines R36 and R42 in the F plasmid CBP, SopB, reduces stimulation of SopA-catalyzed ATP hydrolysis without changing SopA-SopB affinity, suggesting the role of hydrolysis could be analyzed using SopA with normal conformational responses to ATP. Here, we report that strongly reducing SopB-mediated stimulation of ATP hydrolysis results in only slight destabilization of mini-F, although the instability, as well as an increase in mini-F clustering, is proportional to the ATPase deficit. Unexpectedly, the reduced stimulation also increased the frequency of SopA relocation over the nucleoid. The increase was due to drastic shortening of the period spent by SopA at nucleoid ends; average speed of migration per se was unchanged. Reduced ATP hydrolysis was also associated with pronounced deviations in positioning of mini-F, though time-averaged positions changed only modestly. Thus, by specifically targeting SopB-stimulated ATP hydrolysis our study reveals that even at levels of ATPase which reduce the efficiency of splitting clusters and the constancy of plasmid positioning, SopB still activates SopA mobility and plasmid positioning, and sustains near wild type levels of plasmid stability. PMID:24367270

Ah-Seng, Yoan; Rech, Jérôme; Lane, David; Bouet, Jean-Yves

2013-01-01

409

Critical roles of interdomain interactions for modulatory ATP binding to sarcoplasmic reticulum Ca2+-ATPase.  

PubMed

ATP has dual roles in the reaction cycle of sarcoplasmic reticulum Ca(2+)-ATPase. Upon binding to the Ca2E1 state, ATP phosphorylates the enzyme, and by binding to other conformational states in a non-phosphorylating modulatory mode ATP stimulates the dephosphorylation and other partial reaction steps of the cycle, thereby ensuring a high rate of Ca(2+) transport under physiological conditions. The present study elucidates the mechanism underlying the modulatory effect on dephosphorylation. In the intermediate states of dephosphorylation the A-domain residues Ser(186) and Asp(203) interact with Glu(439) (N-domain) and Arg(678) (P-domain), respectively. Single mutations to these residues abolish the stimulation of dephosphorylation by ATP. The double mutation swapping Asp(203) and Arg(678) rescues ATP stimulation, whereas this is not the case for the double mutation swapping Ser(186) and Glu(439). By taking advantage of the ability of wild type and mutant Ca(2+)-ATPases to form stable complexes with aluminum fluoride (E2·AlF) and beryllium fluoride (E2·BeF) as analogs of the E2·P phosphoryl transition state and E2P ground state, respectively, of the dephosphorylation reaction, the mutational effects on ATP binding to these intermediates are demonstrated. In the wild type Ca(2+)-ATPase, the ATP affinity of the E2·P phosphoryl transition state is higher than that of the E2P ground state, thus explaining the stimulation of dephosphorylation by nucleotide-induced transition state stabilization. We find that the Asp(203)-Arg(678) and Ser(186)-Glu(439) interdomain bonds are critical, because they tighten the interaction with ATP in the E2·P phosphoryl transition state. Moreover, ATP binding and the Ser(186)-Glu(439) bond are mutually exclusive in the E2P ground state. PMID:25193668

Clausen, Johannes D; Holdensen, Anne Nyholm; Andersen, Jens Peter

2014-10-17

410

ATP-induced current in isolated outer hair cells of guinea pig cochlea.  

PubMed

1. Electrical and pharmacologic properties of ATP-induced current in outer hair cells isolated from guinea pig cochlea were investigated in the whole-cell recording mode by the use of a conventional patch-clamp technique. 2. Under current-clamp conditions, rapid application of ATP depolarized the outer hair cells resulting in an increase in conductance. The ATP-induced response did not show any desensitization during a continuous application. 3. At a holding potential of -70 mV, the ATP-induced inward current increased in a sigmoidal fashion over the concentration range between 3 microM and 1 mM. The half-maximum concentration (EC50) was 12 microM and the Hill coefficient was 0.93. 4. The ATP-induced current had a reversal potential near 6 mV, which was close to the theoretical value (1 mV) calculated from the Goldman-Hodgkin-Katz equation for permeable intra- and extracellular cations. 5. In the current-voltage (I-V) relationship for the ATP response, a slight inward-going rectification was observed at more positive potentials than the reversal potential. 6. The substitution of extracellular Na+ by equimolar choline+ shifted the reversal potential of the ATP-induced current to more negative values. The substitution of Cs+ in the internal solution by N-methyl-D-glucamine+ (NMG+) shifted it in the positive direction. The reversal potential of ATP-induced current was also shifted to positive values with increasing extracellular Ca2+ concentration. A decrease of intracellular Cl- by gluconate- did not affect the reversal potential, thereby indicating that the ATP-induced current is carried through a large cation channel.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:2358862

Nakagawa, T; Akaike, N; Kimitsuki, T; Komune, S; Arima, T

1990-05-01

411

A positive inotropic effect of ATP in the human cardiac atrium.  

PubMed

We studied contractile effects in isolated electrically driven (1 Hz) atrial preparations from patients undergoing cardiac bypass surgery. ATP concentration dependently (10, 30, and 100 microM) and rapidly decreased force of contraction (negative inotropic effect, NIE) and thereafter more slowly increased force of contraction. The maximum positive inotropic effect (PIE) at 100 microM ATP amounted to 152% of the predrug value (n = 9) and was stable and could be washed out fast and completely. The PIE did not affect time parameters of contraction (time to peak tension and time of relaxation). Moreover, a similar NIE and PIE were noted with adenosine 5'-O-(2-thiotriphosphate) (100 microM). In contrast 2-methyl-thio-ATP did not exert a NIE but only a PIE. In a second set of experiments, preparations were first incubated for 30 min with purinoreceptor antagonists and, in their continuous presence, 100 microM ATP was applied. However, the PIE and NIE of ATP could neither be blocked with suramin (100 and 500 microM), pyridoxalphosphate-6-azophenyl-2',4'-disulfonic acid (50 microM), nor reactive blue 2 (30, 100, and 500 microM), which are known blockers for subtypes of P(2) receptors, or 1,3-dipropyl-cyclopentvl-xanthine (1 and 10 microM), a subtype (A(1) adenosine) P(1) receptor blocker. Likewise, the inhibitor of phospholipase C (PLC) activity (U-73122) and the inhibitor of adenylate cyclase activity (SQ-022563) (10 microM each) failed to affect the NIE and the PIE of ATP. We tentatively suggest that the PIE of ATP might be mediated via P(2X4)-like receptors. In summary, we describe a novel biphasic effect of ATP on force contraction in the isolated human atrium. It is conceivable that ATP plays a physiological role in the human heart, for instance, after cardiac injury to sustain contractility. PMID:18263715

Gergs, Ulrich; Boknik, Peter; Schmitz, Wilhelm; Simm, Andreas; Silber, Rolf-Edgar; Neumann, Joachim

2008-04-01