大肠杆菌K12的cysK突变体的分离与鉴定

Isolation and characterization of cysK mutants of Escherichia coli K12.

作者信息

Fimmel A L, Loughlin R E

出版信息

J Gen Microbiol. 1977 Nov;103(1):37-43. doi: 10.1099/00221287-103-1-37.

Abstract

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.

摘要

胱氨酸K（cysK）突变体缺乏O - 乙酰丝氨酸巯基化酶A [O - 乙酰 - L - 丝氨酸乙酸裂解酶（加硫化氢）；EC 4.2.99.8]，被分离为对亚硒酸盐有抗性或在柠檬酸铋指示培养基上产生黑色反应的菌株。所有突变体都对抑制剂1,2,4 - 三唑有抗性。发现了四个独立的突变体，它们的O - 乙酰丝氨酸巯基化酶活性水平降低，并且NADPH - 亚硫酸盐还原酶[硫化氢：NADP +氧化还原酶；EC 1.8.1.2]的水平部分组成型。同时含有cysE突变和cysK突变的菌株缺乏NADPH - 亚硫酸盐还原酶的组成型水平，表明这些水平是由于诱导剂O - 乙酰丝氨酸在体内的浓度所致。发现cysK基因座与ptsI基因的共转导率为81%。