envM genes of Salmonella typhimurium and Escherichia coli

Abstract

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.

The Enoyl‐[Acyl‐Carrier‐Protein] Reductase (FabI) of Escherichia coli, which Catalyzes a Key Regulatory Step in Fatty Acid Biosynthesis, Accepts NADH and NADPH as Cofactors and is Inhibited by Palmitoyl‐CoA

“…E. coli SFIOO (ompn was described previously [ I l l . E. coli J P l l l 1 , which carries the temperaturesensitivefubl allele [7], was first described by Egan and Russell 1121. E. coli FTlOO and FTlOl are an isogenic pair of strains derived from E. coli JP1 11 1.…”

“…Incubation of E. coli with diazaborine leads to pleiotropic effects on lipid biosynthesis 171. A point mutation in thefib1 gene, which results in a Gly93+Ser exchange in the polypeptide chain, is responsible for the diazaborine-resistant phenotype in E. coli and Salmonella typhimurium [7,81. Another mutation in the fuhl gene leading to a Ser24l+Phe exchange in the FabI protein causes temperature-sensitive growth in E. coli [8].…”

“…The reduction of enoyl-ACP derivatives has previously been shown to be a key regulatory step in endogenous fatty acid biosynthesis and is thought to be involved in regulating the ratio of saturated and unsaturated fatty acids and in the coordination of fatty acid and phospholipid syntheses [4, 51. We have recently determined that the ,fubl (envM) gene encodes the NADH-dependent enoyl-ACP reductase of E. coli [6]. This enzyme, which belongs to the short chaidinsect type alcohol dehydrogenase family, is the target of a group of antibacterial compounds, the diazaborines [7]. The enzymatic activity of the purified FabI protein is inhibited by diazaborine in a noncompetitive manner.…”

An array of Escherichia coli clones over-expressing essential proteins: A new strategy of identifying cellular targets of potent antibacterial compounds

“…Over-expression of prolipoprotein signal peptidase (gene product of lsp) was shown to confer its host cells a high level of resistance to globomycin, an inhibitor of lipoprotein signal peptidase [38]. Turnowsky and colleagues [39] demonstrated that overexpression of EnvM (FabI) protein from the plasmid-borne gene conferred resistance to diazaborine, a specific inhibitor for FabI. Tsay and coworkers [40] screened a thiolactomycin sensitive E. coli strain against an E. coli genomic library for recombinant plasmids that conferred resistance to thiolactomycin, an inhibitor for FabB protein (β-ketoacyl-acyl carrier protein synthase I).…”

Discovery of 4-Pyridone Derivatives as Specific Inhibitors of Enoyl-Acyl Carrier Protein Reductase (FabI) with Antibacterial Activity against Staphylococcus aureus

“…The anti-tuberculosis agent, isoniazid targets the FabI homologue (InhA) of Mycobacterium tuberculosis [6]. Diazaborines were also found to inhibit FabI [7]. Although an alternative enoyl-ACP reductase, FabK, which displays no significant sequence homology to FabI, was identified in Streptococcus pneumoniae, Enterococcus faecalis and Pseudomonas aeruginosa [8], genomic studies have revealed that most bacteria possess FabI as the sole enoyl-ACP reductase.…”