Control of Arginine Biosynthesis in Escherichia coli: Characterization of Arginyl-Transfer Ribonucleic Acid Synthetase Mutants

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RESUMO

The arginyl-transfer ribonucleic acid (Arg-tRNA) synthetase (EC 6.1.1.13, arginine: RNA ligase adenosine monophosphate) mutants, exhibiting nonrepressible synthesis of arginine by exogenous arginine, were employed in studies of several biochemical properties. Two of these mutants possessed Arg-tRNA synthetases with a reduced affinity for arginine, and this enzyme of another mutant had a reduced affinity for arginine-tRNA (tRNAarg). The mutant possessing an Arg-tRNA synthetase with an altered Km for tRNAarg was found to have reduced in vivo aminoacylation of two of the five isoaccepting species of tRNAarg and complete absence of aminoacylation of one of the isoaccepting species.

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