A new method for the isolation of methionyl transfer RNA synthetase mutants from Escherichia coli

Abstract

Six methionine auxotrophs were isolated from an E. coli K-12 strain which required up to 100 times as much methionine for growth as a conventional auxotroph. In these mutants the methionyl-tRNA synthetase had an increased Km for methionine. The Km value for the mutants ranged from 0.48 to 1.63 mM, compared to 0.078 mM for the wild type. The Km (methionine) for S-adenosyl methionine synthetase was not altered.