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)

The ATPase activity of soluble chloroplast coupling factor (CF1) was irreversibly inactivated by phenylglyoxal, an arginine reagent. Under the conditions of inactivation, 2.48 mol of [14C]phenylglyoxal were incorporated per 400,000 g of enzyme when the ATPase was inactivated 50% by the reagent. Isolation of the component polypeptide subunits of the [14C]phenylglyoxal-modified enzyme revealed that the distribution of moles of labeled reagent/mol of subunit was the following: alpha, 0.37; beta, 0.40; gamma, 0.08; delta, none; epsilon, 0.03. CNBr treatment of the isolated alpha and beta subunits and fractionation of the peptides by gel electrophoresis revealed that the radioactivity bound to the alpha subunit was nonspecifically associated with several peptides, while a single peptide derived from the beta subunit contained the majority of the radioactivity associated with this subunit. After treating the isolated beta subunit with trypsin and Staphylococcus aureus protease, a major radioactive peptide was isolated with a sequence Arg-Ile-Thr-Ser-Ile-Lys. This sequence, when compared with the primary structure of the CF1 beta subunit as translated from the gene (Zurawski, G., Bottomley, W., and Whitfeld, P. R. (1982) Proc. Natl. Acad. Sci. U. S. A. 79, 6260-6264) indicated that the arginine marked with the asterisk, the predominant residue modified by phenylglyoxal when the ATPase activity of CF1 is inactivated by the reagent, is Arg 312.
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PMID:Identification of an essential arginine residue in the beta subunit of the chloroplast ATPase. 285 85

A mutant strain of Escherichia coli carrying a mutation in the uncE gene which codes for the c-subunit of the F1F0-ATPase has been isolated and examined. The mutant allele, designated uncE513, results in alanine at position 25 of the c-subunit being replaced by threonine. The mutant F1F0-ATPase appears to be fully assembled and is partially functional with respect to oxidative phosphorylation. The ATPase activity of membranes from the mutant strain is resistant to the inhibitor dicyclohexylcarbodiimide, but this is due to the F1-ATPase being lost from the membranes in the presence of the inhibitor. Mutant membranes from which the F1-ATPase has been removed have a greatly reduced proton permeability compared with similarly treated normal membranes. The results are discussed in relation to a previously proposed mechanism of oxidative phosphorylation.
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PMID:The F1F0-ATPase of Escherichia coli. The substitution of alanine by threonine at position 25 in the c-subunit affects function but not assembly. 286 49

A model for the mechanism of ATP synthase was proposed previously (Cox, G.B., Jans, D.A., Fimmel, A.L., Gibson, F. and Hatch, L. (1984) Biochim. Biophys. Acta 768, 201-208) in which the b subunit of the Fo of Escherichia coli rotated. The driving force was proposed to be an interaction between two charged residues in the membrane, namely, Lys-23 of the b subunit and Asp-61 of the c subunit. To test this proposal the Lys-23 of the b subunit was replaced by threonine using site-directed mutagenesis. The resulting mutant, although it had an impairment in the assembly of the F1F0-ATPase, was normal with respect to oxidative phosphorylation. The role of the a subunit, which had been previously proposed to be a structural one, was reassessed by examination of the possible secondary and tertiary structure of the analogous proteins from several sources. Not only did these subunits appear to have very similar structures, but in each there was a highly conserved helical arm on one of the transmembrane helices which could form a proton channel if it interacted with the Asp-61 of the c subunit. A revised model is therefore presented in which five transmembrane helices from the a subunit and two from the b subunit are surrounded by a ring of c subunits. The highly conserved nature of the structures of the a, b and c subunits from various organisms suggests that the model may have relevance for ATP synthases from bacterial plasma membranes, mitochondria and chloroplasts.
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PMID:The mechanism of ATP synthase: a reassessment of the functions of the b and a subunits. 286 82

A mutant strain of Escherichia coli was isolated in which Gly-48 of the mature epsilon-subunit of the energy-transducing adenosine triphosphatase was replaced by Asp. This amino acid substitution caused inhibition of ATPase activity (about 70%), loss of ATP-dependent proton translocation and lowered oxidative phosphorylation, but did not affect proton translocation through the F0. Purified F1-ATPase from the mutant strain bound to stripped membranes with the same affinity as the normal F1-ATPase. Partial revertant strains were isolated in which Pro-47 of the epsilon-subunit was replaced by Ser or Thr. Pro-47 and Gly-48 are predicted to be residues 2 and 3 in a Type II beta-turn and the Gly-48 to Asp substitution is predicted to cause a change from a Type II to a Type I or III beta-turn. Space-filling models of the beta-turn (residues 46-49) in the normal, mutant and partial revertant epsilon-subunits indicate that the peptide oxygen between Pro-47 and Gly-48 is in a different position to the peptide oxygen between Pro-47 and Asp-48 and that the substitution of Pro-47 by either Ser or Thr restores an oxygen close to the original position. It is suggested that the peptide oxygen between Pro-47 and Gly-48 of the epsilon-subunit is involved either structurally in inter-subunit H-bonding or directly in proton movements through the F1-ATPase.
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PMID:Amino acid substitutions in the epsilon-subunit of the F1F0-ATPase of Escherichia coli. 287 66

In hippocampal slices, somatostatin 14 and its stable analog L363 [cyclo(Phe-Pro-Phe-D-Trp-Lys-Thr)] fail to modify muscarinic signal transduction mediated by stimulation of phosphoinositide breakdown, whereas somatostatin 14 mimics oxotremorine in inhibiting adenylate cyclase activity of hippocampal membranes. The simultaneous addition of somatostatin 14 and oxotremorine elicits a nonadditive convergent inhibition of adenylate cyclase activity. Both L363 and oxotremorine nonadditively stimulate a high-affinity guanosine 5'-triphosphatase activity of hippocampal membranes. This stimulation could be operative in mediating the convergent inhibition of adenylate cyclase activity elicited by the binding of specific ligands to somatostatin and muscarinic recognition sites present in hippocampal membranes. Because L363 competitively displaces muscarinic agonists fand antagonists from their specific recognition sites, one might infer that the two recognition sites interact functionally; that is, somatostatin reduces the efficacy of oxotremorine and/or vice versa.
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PMID:In rat hippocampus, somatostatin 14 and muscarinic receptor ligands modulate an adenylate cyclase belonging to a common domain of the receptor. 288 75

A 50-amino acid peptide predicted by chemical modification studies of F1 and by comparison with adenylate kinase to comprise part of an ATP-binding domain within the beta-subunit of mitochondrial ATP synthase has been synthesized and purified. In the numbering system used for bovine heart beta, the peptide consists of amino acid residues from aspartate 141 at the N-terminal end to threonine 190 at the carboxyl end. In Tris-Cl buffer, pH 7.4, the peptide undergoes a dramatic reaction with ATP resulting in precipitate formation. Analysis of the precipitate shows it to contain both peptide and ATP. Similar to the ATPase activity of F1 and the binding of nucleotide to the enzyme, the capacity of ATP to induce precipitation of the peptide is decreased markedly by lowering pH. Interaction of the peptide with the fluorescent ATP analog, TNP-ATP (2'(3')-O-(2,4-6-trinitrophenyl)-adenosine 5'-triphosphate), can be demonstrated in solution at low concentrations. A 7-fold enhancement in fluorescence is observed when 2.5 microM TNP-ATP interacts with 2.5 microM peptide. Divalent cation is neither required for ATP-induced precipitation of the peptide nor for demonstrating interaction between TNP-ATP and peptide, just as Mg2+ is not required for nucleotide binding to F1. These results indicate that the beta-subunit peptide studied here comprises at least part of a nucleotide-binding domain within the mitochondrial ATP synthase complex.
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PMID:Mitochondrial ATP synthase. Interaction of a synthetic 50-amino acid, beta-subunit peptide with ATP. 289 4

A sequence of 10 amino acids (I-C-S-D-K-T-G-T-L-T) of ion motive ATPases such as Na+/K+-ATPase is similar to the sequence of the beta subunit of H+-ATPases, including that of Escherichia coli (I-T-S-T-K-T-G-S-I-T) (residues 282-291). The Asp (D) residue phosphorylated in ion motive ATPase corresponds to Thr (T) of the beta subunit. This substitution may be reasonable because there is no phosphoenzyme intermediate in the catalytic cycle of F1-ATPase. We replaced Thr-285 of the beta subunit by an Asp residue by in vitro mutagenesis and reconstituted the alpha beta gamma complex from the mutant (or wild-type) beta and wild-type alpha and gamma subunits. The uni- and multisite ATPase activities of the alpha beta gamma complex with mutant beta subunits were about 20 and 30% of those with the wild-type subunit. The rate of ATP binding (k1) of the mutant complex under uni-site conditions was about 10-fold less than that of the wild-type complex. These results suggest that Thr-285, or the region in its vicinity, is essential for normal catalysis of the H+-ATPase. The mutant complex could not form a phosphoenzyme under the conditions where the H+/K+-ATPase is phosphorylated, suggesting that another residue(s) may also be involved in formation of the intermediate in ion motive ATPase. The wild-type alpha beta gamma complex had slightly different kinetic properties from the wild-type F1, possibly because it did not contain the epsilon subunit.
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PMID:A homologous sequence between H+-ATPase (F0F1) and cation-transporting ATPases. Thr-285----Asp replacement in the beta subunit of Escherichia coli F1 changes its catalytic properties. 289 62

A study was made of the activity of transport ATPases of rat myocardial sarcoplasmic reticulum membranes under the conditions of different-character nutrition and under the action of hydrogen fluoride and phosphine. The combined effect of the gases under study was accompanied by activation of Ca2+ ATPase and total ATPase. The character of nutrition, the degree of its adequacy according to retinol, tocopherol, ascorbic acid and essential amino acids (lysine, methionine, and threonine) determined not only the activity of transport ATPases and the phospholipid content of sarcoplasmic reticulum membranes but also the features of the toxic effects of hydrogen fluoride and phosphine. The enrichment of the diet with retinol, tocopherol, ascorbic acid and thiamine reduces the toxic effects of these gases under the conditions of acute and chronic priming as well.
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PMID:[Effect of the combined action of hydrogen fluoride and phosphine on the structural and functional properties of the sarcoplasmic reticulum membranes of the myocardium with nutrition of varying character]. 293 93

Ca2+-Transporting ATPase of rabbit skeletal muscle sarcoplasmic reticulum contains several SH groups which are reactive with N-ethylmaleimide (MalNEt) at pH 7.0. The location of the one which is most reactive with MalNEt (SHN, Kawakita et al. J. Biochem. 87, 609 (1980)) was identified on the amino acid sequence of the ATPase. SHN was labeled by reacting sarcoplasmic reticulum membranes with [14C] MalNEt to a labeling density of 1 mol/mol ATPase. [14C]MalNEt-labeled membranes were digested with thermolysin and 14C-labeled SHN peptides were fractionated by Sephadex LH-20 chromatography to give two major peaks of radioactivity. [14C]-MalNEt-labeled peptides were further purified to homogeneity by C18-reversed phase HPLC. Two radioactive peptides containing modified cysteine (Cys), Leu-Gly-Cys-Thr-Ser and Val-Cys-Lys-Met, were finally obtained in roughly equal amounts and in reasonable recovery. Both of these sequences were found in the amino acid sequence of Ca2+-transporting ATPase (Brandl et al. Cell 44, 597 (1986)), and Cys344 and Cys364 were identified as the targets of MalNEt-modification. Thus, 0.5 mol/mol ATPase of each Cys residue actually reacted rapidly with MalNEt under the conditions leading to SHN-modification. Modification of either one with MalNEt may negatively affect the reactivity of the other. Both of the highly reactive SH groups are located in the neighborhood of Asp351, the phosphorylation site of ATPase.
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PMID:Reactive sulfhydryl groups of sarcoplasmic reticulum ATPase. I. Location of a group which is most reactive with N-ethylmaleimide. 295 11

Smooth muscle myosin can be phosphorylated by myosin light chain kinase at the serine 19 and threonine 18 residues of the two 20,000-dalton light chains (Ikebe, M., Hartshorne, D. J., and Elizinga, M. (1986) J. Biol. Chem. 261, 36-39). These studies with myosin and heavy meromyosin (HMM) compare the effects induced by phosphorylation of serine 19 (M2P and HMM2P) and serine 19 plus threonine 18 (M4P and HMM4P). Formation of M4P altered the KCl dependence of viscosity and Mg2+-ATPase and higher values were maintained at lower ionic strengths, compared to M2P or dephosphorylated myosin (Mo). This is consistent with the stabilization of the 6 S conformation. The tendency for aggregation, as judged by light scattering, followed the sequence M4P greater than M2P greater than Mo. Filaments formed with M4P were more resistant to dissociation by ATP compared to filaments of M2P. Phosphorylation of HMM2P doubled Vmax of actin-activated ATPase with little effect on the apparent affinity for actin. The Mg2+-ATPase of HMM4P exhibited a higher activity at low ionic strength compared to HMM2P and HMMo. Hydrodynamic differences were detected at low ionic strength in the presence of ATP by sedimentation velocity measurements with HMM4P, HMM2P, and HMMo. Proteolysis by papain indicated an increased susceptibility of the head-neck junction of HMM4P compared to HMM2P. These data suggest that the phosphorylation of threonine 18 in addition to serine 19 change the conformation of myosin and HMM and this is associated with altered biological properties.
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PMID:Effects of phosphorylation of light chain residues threonine 18 and serine 19 on the properties and conformation of smooth muscle myosin. 296 56


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