Escherichia coli

About: Escherichia coli is a research topic. Over the lifetime, 59041 publications have been published within this topic receiving 2050337 citations. The topic is also known as: E. coli & E coli jdj.

The extracytoplasmic function sigma factors: role and regulation

Abstract: Alternative sigma factors provide a means of regulating gene expression in response to various extracellular changes. One such class of sigma factors appears to control a variety of functions, including expression of heat-shock genes in Escherichia coli, biosynthesis of alginates and carotenoids in Pseudomonas aeruginosa and Myxococcus xanthus, respectively, iron uptake in E. coli and Pseudomonas spp., nickel and cobalt efflux in Alcaligenes europhus, plant pathogenicity in Pseudomonas syringae and synthesis of outer membrane proteins in Photobacterium sp. strain SS9. Most of these activities deal with extracytoplasmic functions, and such sigmas have been designated as ECF sigma factors. They have also been characterized in Mycobacteria as well as gram-positive bacteria such as Streptomyces coelicolor and Bacillus subtilus and the archaea Sulpholobus acidocaldarius. ECF factors belong to a subfamily of the sigma 70 class, based on their sequence conservation and function across bacterial species. The promoter consensus sequences recognized by the ECF factors are also highly conserved. In most of the cases, the activity of these factors is modulated by a cognate inner membrane protein that has been shown, both in E. coli and in P. aeruginosa, to act as an anti-sigma activity. This inner membrane protein is presumed to serve as a sensor and signalling molecule, allowing an adaptive response to specific environmental change. Presumably, an on-and-off switch of the anti-sigma activity leads to the release of the sigma factor and thereby to the co-ordinate transcription of the specific regulon it governs.

H-NS, the genome sentinel.

Abstract: Two recent reports have indicated that the H-NS protein in Salmonella enterica serovar Typhimurium has a key role in selectively silencing the transcription of large numbers of horizontally acquired AT-rich genes, including those that make up its major pathogenicity islands. Broadly similar conclusions have emerged from a study of H-NS binding to DNA in Escherichia coli. How do these findings affect our view of H-NS and its ability to influence bacterial evolution?

Haemolysin contributes to virulence of extra-intestinal E. coli infections

Abstract: Escherichia coli is the predominant facultative microorganism isolated from the gastrointestinal tract of man and is the most common enteric organism causing extra-intestinal infections in man, particularly of the urinary tract, peritoneum and blood1,2. It is likely that a consortium of virulence factors is responsible for the initiation and severity of extra-intestinal E. coli infections. Properties reported to be associated with the virulence of such infections include haemolysin production3, K1 antigen production4,5, various O antigens5 and Fe sequestration6. For example, it has long been recognized that the ability to lyse erythrocytes is a phenotype more common to E. coli strains isolated from infections than those found in normal faeces3,7–9. It is not clear whether the haemolysin per se is a virulence determinant. However, here we report that an isolated DNA sequence encoding haemolysin, added by recombinant DNA technology to avirulent non-haemolytic faecal isolates of E. coli, results in strains having enhanced virulence as measured in an experimental rat peritonitis model.

Escherichia coli Harboring mcr-1 and blaCTX-M on a Novel IncF Plasmid: First Report of mcr-1 in the United States.

Abstract: The recent discovery of a plasmid-borne colistin resistance gene, mcr-1 , in China heralds the emergence of truly pan-drug-resistant bacteria ([1][1]). The gene has been found primarily in Escherichia coli but has also been identified in other members of the Enterobacteriaceae in human, animal, food