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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.
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TL;DR: It is shown that CNF1 catalyses the deamidation of a glutamine residue at position 63 of Rho, turning it into glutamic acid, which inhibits both intrinsic GTP hydrolysis and that stimulated by its GTPase-activating protein (GAP).
Abstract: Pathogenic Escherichia coli are responsible for a variety of diseases, including diarrhoea, haemolytic uraemic syndrome, kidney infection, septicaemia, pneumonia and meningitis. Toxins called cytotoxic necrotizing factors (CNFs) are among the virulence factors produced by uropathogenic (CNF1)1 or enteropathogenic (CNF2)2 E. coli strains that cause diseases in humans and animals, respectively. CNFs induce an increase in the content of actin stress fibres and focal contacts in cultured cells3,4. Effects of CNFs on the actin cytoskeleton correlated with a decrease in the electrophoretic mobility of the GTP-binding protein Rho4,5 and indirect evidence indicates that CNF1 might constitutively activate Rho6. Here we show that CNF1 catalyses the deamidation of a glutamine residue at position 63 of Rho, turning it into glutamic acid, which inhibits both intrinsic GTP hydrolysis and that stimulated by its GTPase-activating protein (GAP). Thus, this deamidation of glutamine 63 by CNF1 leads to the constitutive activation of Rho, and induces the reorganization of actin stress fibres. To our knowledge, CNF1 is the first example of a bacterial toxin acting by deamidation of a specific target protein.
493 citations
TL;DR: In three geographically diverse communities, a single clonal group accounted for nearly half of community-acquired urinary tract infections in women that were caused by E. coli strains with resistance to trimethoprim-sulfamethoxazole.
Abstract: Background The management of urinary tract infections is complicated by the increasing prevalence of antibiotic-resistant strains of Escherichia coli. We studied the clonal composition of E. coli isolates that were resistant to trimethoprim–sulfamethoxazole from women with community-acquired urinary tract infections. Methods Prospectively collected E. coli isolates from women with urinary tract infections in a university community in California were evaluated for antibiotic susceptibility, O:H serotype, DNA fingerprinting, pulsed-field gel electrophoretic pattern, and virulence factors. The prevalence and characteristics of an antibiotic-resistant clone were evaluated in this group of isolates and in those from comparison cohorts in Michigan and Minnesota. Results Fifty-five of the 255 E. coli isolates (22 percent) from the California cohort were resistant to trimethoprim–sulfamethoxazole as well as other antibiotics. There was a common pattern of DNA fingerprinting, suggesting that the isolates belonged ...
492 citations
TL;DR: These mutants were functionally equivalent to the previous plasmid-based strains for the fermentation of xylose and glucose to ethanol and exceeded theoretical limits on the basis of added sugars because of the additional production of ethanol from the catabolism of complex nutrients.
Abstract: Zymomonas mobilis genes for pyruvate decarboxylase (pdc) and alcohol dehydrogenase II (adhB) were integrated into the Escherichia coli chromosome within or near the pyruvate formate-lyase gene (pfl) Integration improved the stability of the Z mobilis genes in E coli, but further selection was required to increase expression Spontaneous mutants were selected for resistance to high level of chloramphenicol that also expressed high levels of the Z mobilis genes Analogous mutants were selected for increased expression of alcohol dehydrogenase on aldehyde indicator plates These mutants were functionally equivalent to the previous plasmid-based strains for the fermentation of xylose and glucose to ethanol Ethanol concentrations of 544 and 416 g/liter were obtained from 10% glucose and 8% xylose, respectively The efficiency of conversion exceeded theoretical limits (051 g of ethanol/g of sugar) on the basis of added sugars because of the additional production of ethanol from the catabolism of complex nutrients Further mutations were introduced to inactivate succinate production (frd) and to block homologous recombination (recA)
492 citations
TL;DR: It is demonstrated that it is possible to change the fermentation products of an organism, such as E. coli, by the addition of genes encoding appropriate enzymes which form an alternative system for the regeneration of NAD+.
Abstract: The genes encoding essential enzymes of the fermentative pathway for ethanol production in Zymomonas mobilis, an obligately ethanologenic bacterium, were inserted into Escherichia coli under the control of a common promoter. Alcohol dehydrogenase II and pyruvate decarboxylase from Z. mobilis were expressed at high levels in E. coli, resulting in increased cell growth and the production of ethanol as the principal fermentation product from glucose. These results demonstrate that it is possible to change the fermentation products of an organism, such as E. coli, by the addition of genes encoding appropriate enzymes which form an alternative system for the regeneration of NAD+.
491 citations
TL;DR: Data clearly show that the yaeM gene encodes an enzyme, designated 1-deoxy-D-xylulose 5-phosphate reductoisomerase, that synthesizes 2-C-methyl- D-erythritol 4-ph phosphate, in a single step by intramolecular rearrangement and reduction and that this gene is responsible for terpenoid biosynthesis in E. coli.
Abstract: Several eubacteria including Esherichia coli use an alternative nonmevalonate pathway for the biosynthesis of isopentenyl diphosphate instead of the ubiquitous mevalonate pathway. In the alternative pathway, 2-C-methyl-d-erythritol or its 4-phosphate, which is proposed to be formed from 1-deoxy-d-xylulose 5-phosphate via intramolecular rearrangement followed by reduction process, is one of the biosynthetic precursors of isopentenyl diphosphate. To clone the gene(s) responsible for synthesis of 2-C-methyl-d-erythritol 4-phosphate, we prepared and selected E. coli mutants with an obligatory requirement for 2-C-methylerythritol for growth and survival. All the DNA fragments that complemented the defect in synthesizing 2-C-methyl-d-erythritol 4-phosphate of these mutants contained the yaeM gene, which is located at 4.2 min on the chromosomal map of E. coli. The gene product showed significant homologies to hypothetical proteins with unknown functions present in Haemophilus influenzae, Synechocystis sp. PCC6803, Mycobacterium tuberculosis, Helicobacter pyroli, and Bacillus subtilis. The purified recombinant yaeM gene product was overexpressed in E. coli and found to catalyze the formation of 2-C-methyl-d-erythritol 4-phosphate from 1-deoxy-d-xylulose 5-phosphate in the presence of NADPH. Replacement of NADPH with NADH decreased the reaction rate to about 1% of the original rate. The enzyme required Mn2+, Co2+, or Mg2+ as well. These data clearly show that the yaeM gene encodes an enzyme, designated 1-deoxy-d-xylulose 5-phosphate reductoisomerase, that synthesizes 2-C-methyl-d-erythritol 4-phosphate from 1-deoxy-d-xylulose 5-phosphate, in a single step by intramolecular rearrangement and reduction and that this gene is responsible for terpenoid biosynthesis in E. coli.
491 citations