PROPERTIES OF CYSK MUTANTS OF ESCHERICHIA-COLI-K12

Abstract

Triazole and azaserine resistant mutants of E. coli K12 affecting cysK gene coding for O-acetylserine sulfydrylase were isolated. The cysK gene in E. coli is located in the same region of chromosome as the cysK gene in Salmonella typhimurium. All azaserine and some triazole resistant mutants require cysteine for growth at a normal rate. The cysK mutants have reduced sulfate uptake. Stability and transfer by conjugation of triazole resistant phenotype were checked. Differences in sulfate metabolism between closely related organisms E. coli and S. typhimurium are discussed.