Gene/Protein Disease Symptom Drug Enzyme Compound
Pivot Concepts:   Target Concepts:
Query: EC:3.6.1.3 (ATPase)
 65,361 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

ATP consumption by arginyl-tRNA synthetases from Escherichia coli and Bacillus stearothermophilus has been investigated by the firefly luciferin--luciferase assay. Arginyl-tRNA synthetase from E. coli utilizes ATP only for aminocylation of tRNA with a 1:1 stoicheiometry. In contrast, we have shown an adenosine triphosphatase activity of arginyl-tRNA synthetase from B. stearothermophilus in the absence of tRNAArg. Dowex chromatography revealed the formation of ADP by the thermophile enzyme; under aminoacylation conditions, AMP was also formed in amounts stoicheiometric with arginyl-tRNA formation.
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PMID:Adenosine triphosphate consumption by bacterial arginyl-transfer ribonucleic acid synthetases. 38 95

Arginyl-tRNA synthetase from Bacillus stearothermophilus (NCA 1518) has been purified 880-fold to apparent homogeneity as demonstrated by electrophoresis in the presence of sodium dodecyl sulphate. The molecular weight is 59 000 as confirmed by Sephadex G-100 and by sucrose gradient ultracentrifugation. The enzyme is monomeric, no subunits were detected. Its cognate tRNA induces an apparent increase in molecular weight suggesting the dimerisation of the enzyme. Nevertheless, it is not obvious that the enzyme dimer forms prior to the aminoacylation reaction catalysed by the enzyme. An ATPase activity was found associated to the synthetase but can be neglected because the ATP consumption is too low for hampering the arginyl-tRNA synthetase activity. The order of addition of substrates and release of products has been studied by measurements of initial velocity, product inhibition and dead-end inhibition. The nature of the kinetic patterns indicates that the aminoacylation reaction conforms to the classical concept of the mechanism which includes the formation of an enzyme-bound aminoacyl-adenylate as an intermediate in the first step followed by transfer of the amino acid to tRNA. The first partial reaction, measured by the ATP-32PPi exchange or AMP synthesis in the presence of ATP and arginine, requires tRNA, which is consistent with the model in which tRNAArg is an activator of the arginyladenylate synthesis.
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PMID:Arginyl-transfer ribonucleic acid synthetase of Bacillus stearothermophilus. Purification and kinetic analysis. 735 46

ArgRS (arginyl-tRNA synthetase) belongs to the class I aaRSs (aminoacyl-tRNA synthetases), though the majority of ArgRS species lack the canonical KMSK sequence characteristic of class I aaRSs. A DNA fragment of the ArgRS gene from Bacillus stearothermophilus was amplified using primers designed according to the conserved regions of known ArgRSs. Through analysis of the amplified DNA sequence and known tRNA(Arg)s with a published genomic sequence of B. stearothermophilus, the gene encoding ArgRS ( argS ') was amplified by PCR and the gene encoding tRNA(Arg) (ACG) was synthesized. ArgRS contained 557 amino acid residues including the canonical KMKS sequence. Recombinant ArgRS and tRNA(Arg) (ACG) were expressed in Escherichia coli. ArgRS purified by nickel-affinity chromatography had no ATPase activity. The kinetics of ArgRS and cross-recognition between ArgRSs and tRNA(Arg)s from B. stearothermophilus and E. coli were studied. The activities of B. stearothermophilus ArgRS mutated at Lys(382) and Lys(385) of the KMSK sequence and at Gly(136) upstream of the HIGH loop were determined. From the mutation results, we concluded that there was mutual compensation of Lys(385) and Gly(136) for the amino acid-activation activity of B. stearothermophilus ArgRS.
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PMID:Arginyl-tRNA synthetase with signature sequence KMSK from Bacillus stearothermophilus. 1367 19