During infection, Yersinia pestis uses its F1 capsule to enhance survival and cause virulence to mammalian host. Since F1 is produced in large quantities and secreted into the host tissues, it also serves as a major immune target. To hold this detrimental effect under proper control, Y. pestis expresses the caf operon (encoding the F1 capsule) in a temperature-dependent manner. However, additio...

The E-arabinose operon is under both positive and negative control by the product of its regulatory gene, UrQc. We have measured transcription of the arabinose genes by hybridization of 3H-labeled messenger RNA to single-stranded DNA from an arabinose transducing phage in order to study the effect of the regulatory gene on transcription. In strains in which the arabinose regulatory gene is comp...

The Prokaryotic Operon DataBase (ProOpDB, http://operons.ibt.unam.mx/OperonPredictor) constitutes one of the most precise and complete repositories of operon predictions now available. Using our novel and highly accurate operon identification algorithm, we have predicted the operon structures of more than 1200 prokaryotic genomes. ProOpDB offers diverse alternatives by which a set of operon pre...

The dnaK operon of Streptomyces coelicolor contains four genes (5'-dnaK-grpE-dnaJ-hspR). The fourth gene encodes a novel heat shock protein, HspR, which appears so far to be unique to the high-G+C actinomycete group of bacteria. HspR binds with high specificity to three inverted repeat sequences in the promoter region of the S. coelicolor dnaK operon, strongly suggesting a direct role for HspR ...

The E-arabinose operon is under both positive and negative control by the product of its regulatory gene, UrQc. We have measured transcription of the arabinose genes by hybridization of 3H-labeled messenger RNA to single-stranded DNA from an arabinose transducing phage in order to study the effect of the regulatory gene on transcription. In strains in which the arabinose regulatory gene is comp...

Drug efflux protein complexes confer multidrug resistance on bacteria by transporting a wide spectrum of structurally diverse antibiotics. Moreover, organisms can only acquire resistance in the presence of an active efflux pump. The substrate range of drug efflux pumps is not limited to antibiotics, but it also includes toxins, dyes, detergents, lipids, and molecules involved in quorum sensing; hence...

The ability of bacterial pathogens to infect and cause disease is dependent upon their ability to resist antimicrobial components produced by their host, such as bile acids, fatty acids and other detergent-like molecules, and products of the innate immune system (e.g. cationic antimicrobial peptides). Bacterial resistance to the antimicrobial effects of such compounds is often mediated by activ...

OBJECTIVES The purpose of this study was to characterize decreased susceptibility to tigecycline in clinical isolates of Escherichia coli obtained during Phase 3 clinical trials. METHODS Gene expression was analysed by transcriptional profile analysis and RT-PCR. Transposon mutagenesis with IS903kan was used for selection of transposon mutants. Transposon insertions were mapped by DNA sequenc...

Fluoroquinolone resistance is mainly caused by mutations in quinolone resistance-determining regions of DNA gyrase and topoisomerase IV in Escherichia coli. The AcrAB-TolC efflux pump contributes to resistance against fluoroquinolone and other antimicrobials. In this study, we investigated a high-level mechanism of fluoroquinolone resistance in E. coli that was isolated from human clinical samp...

OBJECTIVES The Gram-negative human pathogen Klebsiella oxytoca is often resistant to several antibiotics such as fluoroquinolones, erythromycin, tetracycline, chloramphenicol and others. The aim of this study was to look at the mechanisms leading to this resistance and particularly the role of TolC and efflux mechanisms in determining resistance. METHODS Ciprofloxacin accumulation was measure...