Open AccessIsolation and Characterization of cysK Mutants of Escherichia coli K12
Author(s) -
A L Fimmel,
R. E. Loughlin
Publication year - 1977
Publication title -
journal of general microbiology/journal of general microbiology
Language(s) - English
Resource type - Journals
eISSN - 2059-9323
pISSN - 0022-1287
DOI - 10.1099/00221287-103-1-37
Subject(s) - isolation (microbiology) , escherichia coli , mutant , characterization (materials science) , biology , microbiology and biotechnology , chemistry , genetics , materials science , nanotechnology , gene
cysK mutants, deficient in O-acetylserine sulphydrylase A [O-acetyl-L-serine acetate-lyase (adding hydrogen-sulphide); EC 4.2.99.8], were isolated as strains resistant to selenite or giving a black colour reaction on bismuth citrate indicator medium. All were resistant to the inhibitor I,2,4-triazole. Four independent mutants were found which possessed lowered levels of O-acetylserine sulphydrylase activity and also partially constitutive levels of NADPH-sulphite reductase [hydrogen-sulphide: NADP+ oxidoreductase; EC I.8.I.2]. Strains containing both a cysE mutation and a cysK mutation lacked the constitutive levels of NADPH-sulphite reductase showing that these levels were due to the in vivo concentration of the inducer, O-acetylserine. The cysK locus was found to be 81% cotransducible with the ptsI gene.