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)

The properties of divalent metal.ADP.vanadate (V(i)) complexes of the 6S extended and 10S folded conformations of gizzard myosin before and after UV irradiation have been studied. The half-lives of both 6S and 10S myosin.MgADP.V(i) complexes in the dark at 0 degrees C are on the order of 2 weeks. Brief irradiation with UV light, however, photomodified the enzyme as suggested by changes in the NH(4+)-, K(+)-, and Ca(2+)-ATPase activities, and destabilized the complexes. The 6S complex, when irradiated, released ADP and V(i) rapidly (t1/2 less than or equal to 1 min) as has been observed in comparable experiments with skeletal myosin subfragment 1 (S1) [Grammer et al. (1988) Biochemistry 27, 8408-8415]. The irradiated 10S complex released approximately 20% of the ADP and V(i) rapidly (t1/2 less than or equal to 1 min), but the remainder stayed trapped, possibly as the vanadyl (VO2+).ADP complex, for much longer times (t1/2 approximately 8 h). The site of photomodification was sought by reducing both photomodified 6S and 10S myosin with NaB3H4. Amino acid composition analyses identified [3H]serine as the only labeled residue(s), suggesting that the hydroxymethyl group of serine had been oxidized to an aldehyde as shown previously for photomodified skeletal myosin S1 [Cremo et al. (1989) J. Biol. Chem. 264, 6608-6611]. The 29-kDa NH2-terminal tryptic peptide from the heavy chain was found to contain essentially all of the [3H]serine. Preparations of 6S and 10S [3H]myosin were digested exhaustively with trypsin. An identical [3H]peptide was purified from each preparation and its sequence determined to be Glu169-Asp-Gln-Ser-Ile-Leu-(Cys)-Thr-Gly-[3H]Ser-Gly-Ala-Gly-Ly s183.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Stability and photochemical properties of vanadate-trapped nucleotide complexes of gizzard myosin in the 6S and 10S conformations: identification of an active-site serine. 138 24

Site-specific mutagenesis was used to analyse the role of the residue, Glu309, in the function of the Ca(2+)-ATPase of frog skeletal muscle sarcoplasmic reticulum by substitution with Ala or Lys. At pH 6.0, 100 microM Ca2+ was unable to prevent phosphorylation from Pi, consistent with previous observations on the Ca(2+)-ATPase of rabbit fast twitch muscle [Clarke, D.M., Loo, T.W, Inesi, G. and MacLennan, D.H. (1989) Nature 339, 476-478]. At neutral pH, however, micromolar concentrations of Ca2+ were sufficient to inhibit phosphorylation of the Glu309----Lys mutant from inorganic phosphate, suggesting that at least one high-affinity Ca2+ site was relatively intact in this mutant. The Glu309----Lys mutant was unable to form a phosphoenzyme from ATP at all Ca2+ concentrations studied (up to 12.5 mM), whereas phosphorylation of the Glu309----Ala mutant occurred at 12.5 mM Ca2+, but not at Ca2+ concentrations in the submillimolar range. Kinetic studies demonstrated a reduced rate of dephosphorylation of the E2P intermediate in the Glu309----Lys mutant. A less pronounced stabilization of E2P was observed with the Glu309----Ala mutant, suggesting a possible role of the charge at the position of Glu309 in phosphoenzyme hydrolysis.
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PMID:Mutational analysis of the role of Glu309 in the sarcoplasmic reticulum Ca(2+)-ATPase of frog skeletal muscle. 138 28

beta Lys-155 in the glycine-rich sequence of the beta subunit of Escherichia coli F1-ATPase has been shown to be near the gamma-phosphate moiety of ATP by affinity labeling (Ida, K., Noumi, T., Maeda, M., Fukui, T., and Futai, M. (1991) J. Biol. Chem. 266, 5424-5429). For examination of the roles of beta Lys-155 and beta Thr-156, mutants (beta Lys-155-->Ala, Ser, or Thr; beta Thr-156-->Ala, Cys, Asp, or Ser; beta Lys-155/beta Thr-156-->beta Thr-155/beta Lys-156; and beta Thr-156/beta Val-157-->beta Ala-156/beta Thr-157) were constructed, and their properties were studied extensively. The beta Ser-156 mutant was active in ATP synthesis and had approximately 1.5-fold higher membrane ATPase activity than the wild type. Other mutants were defective in ATP synthesis, had < 0.1% of the membrane ATPase activity of the wild type, and showed no ATP-dependent formation of an electrochemical proton gradient. The mutants had essentially the same amounts of F1 in their membranes as the wild type. Purified mutant enzymes (beta Ala-155, beta Ser-155, beta Ala-156, and beta Cys-156) showed low rates of multisite (< 0.02% of the wild type) and unisite (< 1.5% of the wild type) catalyses. The k1 values of the mutant enzymes for unisite catalysis were lower than that of the wild type: not detectable with the beta Ala-156 and beta Cys-156 enzymes and 10(2)-fold lower with the beta Ala-155 and beta Ser-155 enzymes. The beta Thr-156-->Ala or Cys enzyme showed an altered response to Mg2+, suggesting that beta Thr-156 may be closely related to Mg2+ binding. These results suggest that beta Lys-155 and beta Thr-156 are essential for catalysis and are possibly located in the catalytic site, although beta Thr-156 could be replaced by a serine residue.
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PMID:Effects of mutations of conserved Lys-155 and Thr-156 residues in the phosphate-binding glycine-rich sequence of the F1-ATPase beta subunit of Escherichia coli. 140 Mar 77

The high affinity branched-chain amino acid transport system (LIV-I) in Pseudomonas aeruginosa is composed of five components: BraC, a periplasmic binding protein for branched-chain amino acids; BraD and BraE, integral membrane proteins; BraF and BraG, putative nucleotide-binding proteins. By using a T7 RNA polymerase/promoter system we overproduced the BraD, BraE, BraF, and BraG proteins in Escherichia coli. The proteins were found to form a complex in the E. coli membrane and solubilized from the membrane with octyl glucoside. The LIV-I transport system was reconstituted into proteoliposomes from solubilized proteins by a detergent dilution procedure. In this reconstituted system, leucine transport was completely dependent on the presence of all five Bra components and on ATP loaded internally to the proteoliposomes. Alanine and threonine in addition to branched-chain amino acids were transported by the proteoliposomes, reflecting the substrate specificity of the BraC protein. GTP replaced ATP well as an energy source, and CTP and UTP also replaced ATP partially. Consumption of loaded ATP and concomitant production of orthophosphate were observed only when BraC and leucine, a substrate for LIV-I, were added together to the proteoliposomes, indicating that the LIV-I transport system has an ATPase activity coupled to translocation of branched-chain amino acids across the membrane.
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PMID:Solubilization and reconstitution of the Pseudomonas aeruginosa high affinity branched-chain amino acid transport system. 140 Apr 43

It has been established in experiments on white rats that antituberculous drugs (isoniazid, rifampicin, ethambutol) given in toxic doses affect the liver, its membranes and organelles, inhibit bile production and bioenergy. This is supported by activation of aspartate and alanine aminotransferases, (ALT and AST), alkaline phosphatase in blood serum and acid phosphatase in the liver, by a decrease of the activity of Na(+)-, K(+)-ATPase, succinate dehydrogenase and cytochromoxidase in the liver, lowering of the rate of bile secretion, excretion of bile acids, bilirubin and cholesterol with bile. Provided the drugs are administered in combination, the hepatotoxicity rises, particularly in combination of isoniazid with rifampicin, and especially as isoniazid is combined with rifampicin and ethambutol.
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PMID:[The comparative action of isoniazid, rifampicin and ethambutol on liver function]. 142 54

A region of the mitochondrial genome associated with cytoplasmic male sterility (CMS) in Phaseolus vulgaris was flanked by two different repeated sequences designated x and y. The DNA sequence of the CMS-unique region and a portion of each flanking repeat was determined. Repeat x contained a complete coding copy of the F1 ATPase subunit A (atpA) gene, as well as an open reading frame (orf) predicting a protein of 209 amino acids. The TGA termination codon of the atpA gene and the ATG initiation codon of orf209 were overlapping. These reading frames were oriented with their 3' ends proximal to the CMS-unique region. The CMS-unique region of 3736 nucleotides contained numerous orfs. The longest of these predicted proteins being of 239, 98 and 97 amino acids. The 3' coding and 3' flanking regions of orf98 were derived from an internal region of the higher plant chloroplast tRNA alanine intron. The region of repeat y immediately adjacent to the CMS-unique region contained the 111 carboxy-terminal coding residues of the apocytochrome b (cob) gene. This segment was oriented with its 5' end proximal to the CMS-unique region, but cob gene sequences were not fused to an initiation codon within the unique region.
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PMID:Organization of ATPA coding and 3' flanking sequences associated with cytoplasmic male sterility in Phaseolus vulgaris L. 142 17

The repair of anthramycin-DNA adducts by the UVR proteins in Escherichia coli follows two pathways: the adducts may be incised by the combined actions of UVRA, UVRB, and UVRC, or alternatively, the anthramycin may be removed by UVRA and UVRB in the absence of UVRC and with no DNA strand incision. To assess the competition between these two competing pathways, the rate of UVRABC-mediated excision repair of anthramycin-N2-guanine DNA adducts and the rate of UVRAB-mediated removal of the adduct were measured with single end-labeled DNAs under identical reaction conditions. UVR protein concentrations of 15 nM UVRA, 100 nM UVRB, and 10 nM UVRC protein were chosen to mimic in vivo concentrations. With these UVR protein concentrations and anthramycin-DNA concentrations of 1-2 nM the incision reaction and the release reactions are described by first-order kinetics. The rate of the UVRABC reaction, measured as the increase in incised fragments, was six to seven times faster than the rate of the UVRAB reaction, measured as the decrease in incised fragments. The UVRABC incision rate on anthramycin-modified linear DNA was four to five times the incision rate measured on the same DNA irradiated with ultraviolet light. We also investigated the role of the ATPase function of UVRB in UVRAB-mediated anthramycin removal. We found that a UVRB analogue with alanine at arginine 51, which retains near wild type ATPase activity, supported removal of anthramycin in the presence of UVRA, whereas a UVRB analogue with alanine at lysine 45, which abolishes the ATPase activity, did not. UVRB*, a specific proteolytic cleavage product of UVRB which retains the ATPase activity, did support removal of anthramycin in the presence of UVRA.
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PMID:A comparison of the rates of reaction and function of UVRB in UVRABC- and UVRAB-mediated anthramycin-N2-guanine-DNA repair. 144 12

The activity of fungal and plant plasma membrane H(+)-ATPases seems to be regulated by modulation of the interaction of an inhibitory domain at the C-terminus with the active site. In the yeast ATPase, a mutation at the active site (Ala547- > Val) and a deletion of the C-terminus result in constitutive activation. A double Ser911- > Ala, Thr912- > Ala mutation at the C-terminus (defining putative phosphorylation sites) locks the enzyme in the inhibited state and can be suppressed by the Ala547- > Val mutation at the active site. This provides genetic evidence for domain interaction. In plant ATPase, proteolytic removal of the C-terminus also results in constitutive activation. A peptide covering a region of the plant C-terminus with homology to the yeast C-terminus inhibits the truncated plant ATPase. This suggests similar regulatory mechanisms in fungal and plant ATPases.
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PMID:The regulatory domain of fungal and plant plasma membrane H(+)-ATPase. 144 59

Site-specific mutagenesis of the sarcoplasmic reticulum Ca(2+)-ATPase was used to investigate the functional role of Lys684 located in the "hinge-domain", a highly conserved region of the cation-transporting ATPases. Mutation of Lys684 to Arg, Ala, His and Gln resulted in complete loss of calcium transport function and ATPase activity. For the Lys684- > Ala, His, Gln mutants, this coincided with a loss of the ability to form a phosphorylated intermediate from ATP or Pi, whereas the Lys684- > Arg mutant retained the ability to phosphorylate from ATP with normal apparent affinity, demonstrating the importance of the positive charge. On the other hand, no phosphorylation was observed with Pi as substrate in this mutant. Examination of the partial reactions following phosphorylation from ATP in the Lys684- > Arg mutant demonstrated a reduction of the rate of transformation of the ADP-sensitive phosphoenzyme intermediate (E1P) to the ADP-insensitive phosphoenzyme intermediate (E2P), which could account for the loss of transport function. Once accumulated, the E2P intermediate was able to decompose rapidly in the presence of K+ at neutral pH. In the Lys684- > Ala mutant, nucleotides were found to protect with normal affinity against intramolecular cross-linking induced with glutaraldehyde, indicating that the nucleotide binding site was intact. These data point to a role of Lys684 in the binding and transfer of phosphate to the protein, and in the transport-associated conformational changes of the phosphorylation site.
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PMID:Mutational analysis of the role of Lys684 in the Ca(2+)-ATPase of sarcoplasmic reticulum. 144 72

Use of the nonphosphorylating beta,gamma-bidentate chromium(III) complex of ATP to induce a stable Ca(2+)-occluded form of the sarcoplasmic reticulum Ca(2+)-ATPase was combined with molecular sieve high performance liquid chromatography of detergent-solubilized protein to examine the ability of the Ca(2+)-ATPase mutants Gly-233-->Glu, Gly-233-->Val, Glu-309-->Gln, Gly-310-->Pro, Pro-312-->Ala, Ile-315-->Arg, Leu-319-->Arg, Asp-703-->Ala, Gly-770-->Ala, Glu-771-->Gln, Asp-800-->Asn, and Gly-801-->Val to occlude Ca2+. This provided a new approach to identification of amino acid residues involved in Ca2+ binding and in the closure of the gates to the Ca2+ binding pocket of the Ca(2+)-ATPase. The "phosphorylation-negative" mutant Asp-703-->Ala and mutants of ADP-sensitive phosphoenzyme intermediate type were fully capable of occluding Ca2+, as was the mutant Gly-770-->Ala. Mutants in which carboxylic acid-containing residues in the putative transmembrane segments had been substituted ("Ca(2+)-site mutants") and mutant Gly-801-->Val were unable to occlude either of the two calcium ions. In addition, the mutant Gly-310-->Pro, previously classified as ADP-insensitive phosphoenzyme intermediate type (Andersen, J.P., Vilsen, B., and MacLennan, D.H. (1992). J. Biol. Chem. 267, 2767-2774), was unable to occlude Ca2+, even though Ca(2+)-activated phosphorylation from MgATP took place in this mutant.
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PMID:CrATP-induced Ca2+ occlusion in mutants of the Ca(2+)-ATPase of sarcoplasmic reticulum. 146 90


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