Turnowsky F, Fuchs K, Jeschek C, Högenauer G
Institut für Mikrobiologie, Universität Graz, Austria.
J Bacteriol. 1989 Dec;171(12):6555-65. doi: 10.1128/jb.171.12.6555-6565.1989.
Conjugation and bacteriophage P1 transduction experiments in Escherichia coli showed that resistance to the antibacterial compound diazaborine is caused by an allelic form of the envM gene. The envM gene from Salmonella typhimurium was cloned and sequenced. It codes for a 27,765-dalton protein. The plasmids carrying this DNA complemented a conditionally lethal envM mutant of E. coli. Recombinant plasmids containing gene envM from a diazaborine-resistant S. typhimurium strain conferred the drug resistance phenotype to susceptible E. coli cells. A guanine-to-adenine exchange in the envM gene changing a Gly codon to a Ser codon was shown to be responsible for the resistance character. Upstream of envM a small gene coding for a 10,445-dalton protein was identified. Incubating a temperature-sensitive E. coli envM mutant at the nonpermissive temperature caused effects on the cells similar to those caused by treatment with diazaborine, i.e., inhibition of fatty acid, phospholipid, and lipopolysaccharide biosynthesis, induction of a 28,000-dalton inner membrane protein, and change in the ratio of the porins OmpC and OmpF.
在大肠杆菌中进行的接合和噬菌体P1转导实验表明，对抗菌化合物重氮硼嗪的抗性是由envM基因的等位形式引起的。鼠伤寒沙门氏菌的envM基因被克隆并测序。它编码一种27,765道尔顿的蛋白质。携带该DNA的质粒补充了大肠杆菌的一种条件致死性envM突变体。含有来自重氮硼嗪抗性鼠伤寒沙门氏菌菌株的envM基因的重组质粒赋予了敏感大肠杆菌细胞耐药表型。envM基因中鸟嘌呤到腺嘌呤的交换将一个甘氨酸密码子变为丝氨酸密码子，这被证明是抗性特征的原因。在envM上游鉴定出一个编码10,445道尔顿蛋白质的小基因。在非允许温度下培养温度敏感的大肠杆菌envM突变体对细胞产生的影响与用重氮硼嗪处理产生的影响相似，即抑制脂肪酸、磷脂和脂多糖的生物合成，诱导一种28,000道尔顿的内膜蛋白，并改变孔蛋白OmpC和OmpF的比例。
