Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound   Target Concepts: Gene/Protein Disease Symptom Drug Enzyme Compound

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Query: EC:3.6.1.3 (ATPase)
65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

31P nuclear magnetic resonance spectra of glycolyzing, anaerobic Escherichia coli cells and their perchloric acid extracts were obtained at 145.7 MHz. Time-dependent intracellular concentrations of nucleoside di- and triphosphates, Pi, and sugar phosphates were measured during glycolysis with 2-min resolution, while intracellular and extra-cellular pH values were monitored simultaneously. Upon glucose addition, anaerobic E. coli cells rapidly produce acids and develop a transmembrane pH gradient (delta pH). Glycolysis rates were calculated from the changes in the external pH. It was found that glycolysis rates are strongly dependent on internal pH, sharply decreasing when the pH drops below approximately 7.2. The ATPase inhibitor, dicyclohexylcarbodiimide (DCCD), prevented NTP hydrolysis and inhibited delta pH formation. The uncoupler, carbonyl cyanide p-triflouromethoxyphenyl hydrazone (FCCP), drastically reduced both the delta pH and the NTP level. When the cells were previously treated with DCCD, FCCP collapsed the delta pH while the NTP levels remained high. It is concluded that ATP produced by glycolysis is hydrolyzed by the membrane ATPase to generate a delta pH and that FCCP stimulates ATP hydrolysis by ATPase and collapses the proton gradient.
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PMID:31P nuclear magnetic resonance studies of bioenergetics and glycolysis in anaerobic Escherichia coli cells. 2 85

It is shown that the second cholera toxin, Zot, ORF3 product of Pseudomonas plasmid pKB740, and ORF424 product of bacteriophage Pf1 are a group of closely related proteins containing a modified version of the purine NTP-binding motif, with a drastic substitution of tyrosine for a conserved glycine. They are distantly but reliably related to the product of gene I of filamentous bacteriophages which is a putative ATPase containing the classical NTP-binding motif and is involved in bacteriophage assembly and exit from the bacterial cell. Hydropathy analysis suggests that the Zot and gene I product may have a similar transmembrane topology. It is hypothesized that Zot may possess ATPase activity and modify the membrane structure of its target cells in an ATP-dependent fashion. Genes for Zot and the related protein of pKB740 are likely to have evolved from gene I of a Pf1-like bacteriophage.
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PMID:The second cholera toxin, Zot, and its plasmid-encoded and phage-encoded homologues constitute a group of putative ATPases with an altered purine NTP-binding motif. 142 34

A novel DNA helicase has been isolated from Saccharomyces cerevisiae. This DNA helicase co-purified with replication factor C (RF-C) during chromatography on S-Sepharose, DEAE-silica gel high performance liquid chromatography (HPLC), Affi-Gel Blue-agarose, heparin-agarose, single-stranded DNA-cellulose, fast protein liquid chromatography MonoS, and hydroxyapatite HPLC. Surprisingly, the helicase could be separated from RF-C by sedimentation on a glycerol gradient in the presence of 200 mM NaCl. The helicase is probably a homodimer of a 60-kDa polypeptide, which by UV cross-linking has been shown to bind ATP. It has a single-stranded DNA-dependent ATPase activity, with a Km for ATP of 60 microM. The DNA helicase activity depends on the hydrolysis of NTP (dNTP), with ATP and dATP the most efficient cofactors, followed by CTP and dCTP. The DNA helicase has a 5' to 3' directionality and is only marginally stimulated by coating the single-stranded DNA with the yeast single-stranded DNA-binding protein RF-A.
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PMID:A Saccharomyces cerevisiae DNA helicase associated with replication factor C. 146 28

The apparent DNA site size obtained from an assay monitoring the ATPase activity of Escherichia coli recA protein (n = 3.5) differs from that determined from a direct DNA binding assay (n = 7) done under identical conditions. Investigation of this discrepancy indicates that at a DNA:protein ratio of 3.5:1, one-half of the recA protein population is less sensitive to ATPase activity inhibition by the nonhydrolyzable ATP analogue adenosine 5'-O-(3-thiotriphosphate) (ATP gamma S), suggesting that the recA protein filament is asymmetric with respect to NTP affinity. This asymmetry does not depend on the presence of ATP gamma S since the apparent Km for ATP derived from single-stranded DNA-dependent ATP hydrolysis activity is dependent on the DNA:protein ratio. Three models are proposed to account for the observed site size discrepancy and the NTP binding affinity asymmetry. They differ mainly in the intrinsic site size for each recA protein monomer and in the number of DNA-binding sites/recA molecule. Gel filtration of recA-single-stranded DNA complexes at different DNA:protein ratios complements the enzymological data and provides an additional method of distinguishing among the proposed models. The phenomenon of subunit nonequivalence within the recA protein presynaptic filament may provide a molecular basis for understanding how recA protein can discriminate between different DNA molecules during homologous pairing.
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PMID:Asymmetry in the recA protein-DNA filament. 182

The effect of a protonophoric uncoupler (CCCP) on the different cellular compartments was investigated in yeast grown aerobically on lactate. These cells were incubated in a resting cell medium under three conditions; in aerobiosis with lactate or glucose or in anaerobiosis with glucose as energetic substrate. For each condition, in vivo 31P NMR was used to measure pH gradients across vacuolar and plasma membrane and phosphorylated compound levels. Respiratory rate (aerobic conditions) and TPP+ uptake were measured independently. Concerning the polyphosphate metabolism, spontaneous NMR-detected polyphosphate breakdown occurred, in anaerobiosis and in the absence of CCCP. In contrast, in aerobiosis, polyphosphate hydrolysis was induced by addition of either CCCP or a vacuolar membrane ATPase-specific inhibitor, bafilomycin A1. Moreover, polyphosphates were totally absent in a null vacuolar ATPase activity mutant. The vacuolar polyphosphate content depended on two factors: vacuolar pH value, strictly linked to the vacuolar H(+)-ATPase activity, and inorganic phosphate concentration. CCCP was more efficient in dissipating the proton electrochemical gradient across vacuolar and mitochondrial membranes than across the plasma membrane. This discrepancy can be essentially explained by a difference of stimulability of each proton pump involved. As long as the energetic state (measured by NDP + NTP content) remains high, the plasma membrane proton ATPase is able to compensate the proton leak. Moreover, this ATPase contributes only partially to the generation of delta pH. The maintenance of the delta pH across the plasma membrane, that of the energetic state, and the cellular TPP+ uptake depend on the nature of the ATP-producing process.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Differential sensitivity of the cellular compartments of Saccharomyces cerevisiae to protonophoric uncoupler under fermentative and respiratory energy supply. 183 54

The Ca2+ transport by sarcoplasmic reticulum fragments was studied. ATP, CTP, ITP, GTP and UTP provided the same Ca-pump efficiency. When the NTP was exhausted, Ca2+ actively accumulated from the sarcoplasmic reticulum vesicles outflow, and with the higher rate of ATP was a substrate. The Ca-ATPase conformational transitions induced by ATP are discussed for their role in the provision of energy.
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PMID:[Ability of nucleoside triphosphates to provide for Ca 2+ transport by sarcoplasmic reticulum fragments]. 214 50

Limited tryptic digestion of Escherichia coli transcription termination factor rho [an RNA-dependent nucleoside triphosphatase (NTPase)] yields predominantly two fragments (f1 and f2) when the protein is bound to both poly(C) and ATP. The apparent molecular masses of the two fragments are 31 kDa for f1 and 15 kDa for f2, adding up to the molecular mass of the intact rho polypeptide chain (46 kDa). Sequence analysis of the amino termini demonstrates that f1 is derived from the amino-terminal portion of rho and that the trypsin cleavage that defines f2 occurs at lysine-283. These results suggest that, in the liganded (activated) form, the native rho protein monomer is organized into two distinct structural domains that are separable by a single proteolytic cleavage. The f1 fragment, purified from NaDodSO4/polyacrylamide gels and renatured, binds poly(C) but the f2 fragment does not; neither regains any ATPase activity. ATP- and polynucleotide-dependent changes in the rate of proteolysis and in the character of the fragments produced suggest that rho undergoes a series of conformational transitions as a consequence of RNA binding, NTP binding and NTP hydrolysis. The rate of loss of rho ATPase activity and of intact rho monomers is slower in the presence of adenosine 5'-[gamma-thio]triphosphate than in the presence of either ATP or ADP, indicating that the hydrolysis of ATP may result in different conformational effects than does the binding of this ligand. These findings are discussed within the context of recent models of rho-dependent transcription termination.
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PMID:Escherichia coli transcription termination factor rho has a two-domain structure in its activated form. 258 Mar 3

We previously demonstrated that the hydrolysis of GTP by canine cardiac sarcoplasmic reticulum is not sensitive to calcium and does not support the translocation of calcium and oxalate into the vesicular space. In response to GTP, however, calcium is accumulated into a compartment which is sensitive to pH and ionophore. In the present paper, we further explored the relationship between GTP hydrolysis and GTP-induced calcium accumulation. Both ATP- and GTP-induced calcium accumulation were prevented by the sulfhydryl reagent, N-ethylmaleimide (NEM; I50 = 0.2 mM). In contrast, the sensitivity of NTP hydrolysis to NEM differed markedly; GTPase activity was not affected by NEM, whereas ATPase activity was markedly inhibited. Conversely, although the GTPase was noncompetitively inhibited by the ATP analogue, adenylyl imidodiphosphate (Ki = 8 microM), and was competitively inhibited by the GTP analogue, guanylyl imidodiphosphate (Ki = 60 microM), GTP-induced calcium accumulation was not affected by the NTP analogues at any concentration. Therefore, the GTP-dependent accumulation of calcium into the pH- and ionophore-sensitive compartment of cardiac SR may not require GTP hydrolysis but may be dependent on GTP binding. The previously reported noncompetitive inhibition of the GTPase by ATP was also observed when the calcium-dependent hydrolysis of ATP was prevented by NEM (Ki = 1.2 microM). Along with the noncompetitive inhibition of the GTPase by adenylyl imidodiphosphate, the inhibition of the GTP by ATP in the presence of NEM suggests that ATP binding may be involved in the observed inhibition. The Ki for the noncompetitive inhibition of GTPase activity is compatible with ATP binding to the high affinity catalytic site of the ATPase. Thus, although GTP-induced calcium accumulation differs somewhat from ATP-dependent calcium translocation, the similarities between the two processes (i.e. similar time courses and sensitivity to pH, ionophore, and sulfhydryl modification) suggest that they may be related in some manner.
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PMID:Nucleotide specificity of cardiac sarcoplasmic reticulum. GTP-induced calcium accumulation and GTPase activity. 299 Dec 55

The effects of pyrophosphate on RNA binding and ATPase activities of Escherichia coli transcription termination factor rho have been studied. Mutant rho-115 protein has a temperature-sensitive RNA-dependent ATPase activity due to the thermolability of binding to RNA [Kent, R.B. & Guterman, S.K. (1981) Fed. Proc. Fed. Am. Soc. Exp. Biol. 40, 1765 (abstr.)]. The presence of either ATP or pyrophosphate at comparable concentrations stabilizes the binary complex of rho and poly(C) at high temperature. ADP at 8-fold greater concentration also stabilizes the mutant rho-RNA binary complex. Pyrophosphate is a noncompetitive inhibitor (Ki = 0.07 mM) of rho poly(C)-dependent ATPase, an activity that is required for rho-mediated termination. These results suggest the existence of a regulatory site on the rho molecule. We suggest that rho NTPase is regulated by RNA polymerase (EC 2.7.7.6) so that during transcription elongation the RNA polymerase competes successfully with rho for substrates and inhibits rho NTPase with product pyrophosphate. Further, RNA polymerase pausing may result in reduced pyrophosphate and increased NTP concentrations, allowing rho NTPase to function.
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PMID:Pyrophosphate inhibition of rho ATPase: a mechanism of coupling to RNA polymerase activity. 612 40

The gene 4 protein of bacteriophage T7 is both a primase and a helicase. In this paper, we present a detailed description of a third activity, single-stranded DNA-dependent nucleoside 5'-triphosphate hydrolysis, and show that this activity is coupled to the unidirectional translocation of the gene 4 protein on single-stranded DNA (Tabor, S., and Richardson, C.C. (1981) Proc. Natl. Acad. Sci. U. S. A. 78, 205-209). The competitive inhibitor of NTP hydrolysis, beta, gamma-methylene dTTP, is also a potent inhibitor of gene 4 protein-dependent, RNA-primed DNA synthesis; inhibition is not due to a direct inhibition of T7 DNA polymerase or RNA primer synthesis. We conclude that the energy derived from the hydrolysis of NTPs by the gene 4 protein is required for translocation of the protein to primase recognition sites. Measurement of the rates of hydrolysis of NTPs using a variety of DNAs of known structure and length support the unidirectional translocation of the gene 4 protein on single-stranded DNA. Duplex DNA, RNA, and single-stranded DNA coated with single-stranded DNA-binding protein do not serve as effectors for the nucleoside triphosphatase of the gene 4 protein. Kinetic data suggest that the gene 4 protein does not remain bound to newly synthesized oligoribonucleotide primers but continues to search for other primase recognition sites. Although all the predominant naturally occurring NTPs except rCTP are hydrolyzed by the gene 4 protein, the enzyme shows specificity for dTTP with a Km of 0.4 mM. In the accompanying paper (Matson, S.W., Tabor, S., and Richardson, C.C. (1983) J. Biol. Chem. 258, 14017-14024), we show that the hydrolysis of NTPs is also required for the protein to function as a helicase in duplex regions of DNA.
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PMID:DNA-dependent nucleoside 5'-triphosphatase activity of the gene 4 protein of bacteriophage T7. 613 75


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