Two heterologously expressed <Emphasis Type="Italic">Planobispora rosea</Emphasis> proteins cooperatively induce <Emphasis Type="Italic">Streptomyces lividans</Emphasis> thiostrepton uptake and storage from the extracellular medium

Background  

A bacterial artificial chromosomal library of Planobispora rosea, a genetically intractable actinomycete strain, was constructed using Escherichia coli - Streptomyces artificial chromosome (ESAC) and screened for the presence of genes known to be involved in the biosynthesis of antibiotics.     

Influence of hydrological conditions on the <Emphasis Type="Italic">Escherichia coli</Emphasis> population structure in the water of a creek on a rural watershed

Background  

Escherichia coli is a commensal bacterium of the gastro-intestinal tract of human and vertebrate animals, although the aquatic environment could be a secondary habitat. The aim of this study was to investigate the effect of hydrological conditions on the structure of the E. coli population in the water of a creek on a small rural watershed in France composed of pasture and with human occupation.     

Crystal structure of the YffB protein from <Emphasis Type="Italic">Pseudomonas aeruginosa</Emphasis> suggests a glutathione-dependent thiol reductase function

Background  

The yffB (PA3664) gene of Pseudomonas aeruginosa encodes an uncharacterized protein of 13 kDa molecular weight with a marginal sequence similarity to arsenate reductase from Escherichia coli. The crystal structure determination of YffB was undertaken as part of a structural genomics effort in order to assist with the functional assignment of the protein.     

Evaluation of Petrifilm™ Select <Emphasis Type="Italic">E. coli</Emphasis> Count Plate medium to discriminate antimicrobial resistant <Emphasis Type="Italic">Escherichia coli</Emphasis>

Background  

Screening and enumeration of antimicrobial resistant Escherichia coli directly from samples is needed to identify emerging resistant clones and obtain quantitative data for risk assessment. Aim of this study was to evaluate the performance of 3M™ Petrifilm™ Select E. coli Count Plate (SEC plate) supplemented with antimicrobials to discriminate antimicrobial-resistant and non-resistant E. coli.     

Verotoxigenic <Emphasis Type="Italic">Escherichia coli</Emphasis> O157:H7 from Swedish cattle; isolates from prevalence studies versus strains linked to human infections - A retrospective study

Background  

Several cases of human infection caused by verotoxin-producing Escherichia coli (VTEC) O157:H7 in Sweden have been connected with cattle farm visits. Between 1996 and 2002, 18 farms were classified as the source of human cases with isolation of EHEC (Enterohaemorrhagic Escherichia coli) after VTEC O157:H7 had been isolated from cattle on those farms.     

Crystal structure of nitrogen regulatory protein IIA<Superscript>Ntr</Superscript> from <Emphasis Type="Italic">Neisseria meningitidis</Emphasis>

Background  

The NMB0736 gene of Neisseria meningitidis serogroup B strain MC58 encodes the putative nitrogen regulatory protein, IIA^Ntr (abbreviated to NM-IIA^Ntr). The homologous protein present in Escherichia coli is implicated in the control of nitrogen assimilation. As part of a structural proteomics approach to the study of pathogenic Neisseria spp., we have selected this protein for structure determination by X-ray crystallography.     

Antimicrobial resistance and virulence factors in <Emphasis Type="Italic">Escherichia coli</Emphasis> from swedish dairy calves

Background  

In Sweden, knowledge about the role of enteropathogenic Escherichia coli in neonatal calf diarrhea and the occurrence of antimicrobial resistance in E. coli from young calves is largely unknown. This has therapeutic concern and such knowledge is also required for prudent use of antimicrobials.     

RecA Proteins from <Emphasis Type="Italic">Deinococcus geothermalis</Emphasis> and <Emphasis Type="Italic">Deinococcus murrayi</Emphasis> - Cloning,Purification and Biochemical Characterisation

Background  

Escherichia coli RecA plays a crucial role in recombinational processes, the induction of SOS responses and mutagenic lesion bypasses. It has also been demonstrated that RecA protein is indispensable when it comes to the reassembly of shattered chromosomes in γ-irradiated Deinococcus radiodurans, one of the most radiation-resistant organisms known. Moreover, some functional differences between E. coli and D. radiodurans RecA proteins have also been shown.     

Metabolic engineering of a reduced-genome strain of Escherichia coli for L-threonine production

Background  

Deletion of large blocks of nonessential genes that are not needed for metabolic pathways of interest can reduce the production of unwanted by-products, increase genome stability, and streamline metabolism without physiological compromise. Researchers have recently constructed a reduced-genome Escherichia coli strain MDS42 that lacks 14.3% of its chromosome.     

Chromosomal duplications and cointegrates generated by the bacteriophage lamdba Red system in Escherichia coli K-12

Background  

An Escherichia coli strain in which RecBCD has been genetically replaced by the bacteriophage λ Red system engages in efficient recombination between its chromosome and linear double-stranded DNA species sharing sequences with the chromosome. Previous studies of this experimental system have focused on a gene replacement-type event, in which a 3.5 kbp dsDNA consisting of the cat gene and flanking lac operon sequences recombines with the E. coli chromosome to generate a chloramphenicol-resistant Lac- recombinant. The dsDNA was delivered into the cell as part of the chromosome of a non-replicating λ vector, from which it was released by the action of a restriction endonuclease in the infected cell. This study characterizes the genetic requirements and outcomes of a variety of additional Red-promoted homologous recombination events producing Lac+ recombinants.     

Expansion of a chromosomal repeat in Escherichia coli: roles of replication, repair, and recombination functions

Background  

Previous studies of gene amplification in Escherichia coli have suggested that it occurs in two steps: duplication and expansion. Expansion is thought to result from homologous recombination between the repeated segments created by duplication. To explore the mechanism of expansion, a 7 kbp duplication in the chromosome containing a leaky mutant version of the lac operon was constructed, and its expansion into an amplified array was studied.     

Prevalence and characterization of plasmids carrying sulfonamide resistance genes among <Emphasis Type="Italic">Escherichia coli</Emphasis> from pigs,pig carcasses and human

Background  

Sulfonamide resistance is very common in Escherichia coli. The aim of this study was to characterize plasmids carrying sulfonamide resistance genes (sul1, sul2 and sul3) in E. coli isolated from pigs and humans with a specific objective to assess the genetic diversity of plasmids involved in the mobility of sul genes.     

Common and specific genomic sequences of avian and human extraintestinal pathogenic <Emphasis Type="Italic">Escherichia coli</Emphasis> as determined by genomic subtractive hybridization

Background  

Suppression subtractive hybridization (SSH) strategy was used with extraintestinal pathogenic Escherichia coli (EXPEC) that cause avian colibacillosis (avian pathogenic E. coli or APEC) and human urinary tract infections (uropathogenic E. coli or UPEC) to determine if they possessed genes that were host and/or niche specific. Both APEC and UPEC isolates were used as tester and driver strains in 4 different SSHs in order to obtain APEC- and UPEC-specific subtraction fragments (SFs).     

Diarrhea-associated biofilm formed by enteroaggregative <Emphasis Type="Italic">Escherichia coli</Emphasis> and aggregative <Emphasis Type="Italic">Citrobacter freundii</Emphasis>: a consortium mediated by putative F pili

Background  

Enteroaggregative Escherichia coli (EAEC) are enteropathogenic strains identified by the aggregative adhesion (AA) pattern that share the capability to form biofilms. Citrobacter freundii is classically considered as an indigenous intestinal species that is sporadically associated with diarrhea.     

Two distinct regions in the model protein Peb1 are critical for its heterologous transport out of <Emphasis Type="Italic">Escherichia coli</Emphasis>

Background  

Escherichia coli is frequently the first-choice host organism in expression of heterologous recombinant proteins in basic research as well as in production of commercial, therapeutic polypeptides. Especially the secretion of proteins into the culture medium of E. coli is advantageous compared to intracellular production due to the ease in recovery of the recombinant protein. Since E. coli naturally is a poor secretor of proteins, a few strategies for optimization of extracellular secretion have been described. We have previously reported efficient secretion of the diagnostically interesting model protein Peb1 of Campylobacter jejuni into the growth medium of Escherichia coli strain MKS12 (ΔfliCfliD). To generate a more detailed understanding of the molecular mechanisms behind this interesting heterologous secretion system with biotechnological implications, we here analyzed further the transport of Peb1 in the E. coli host.     

Computational identification of rare codons of <Emphasis Type="Italic">Escherichia coli</Emphasis> based on codon pairs preference

Background  

Codon bias is believed to play an important role in the control of gene expression. In Escherichia coli, some rare codons, which can limit the expression level of exogenous protein, have been defined by gene engineering operations. Previous studies have confirmed the existence of codon pair's preference in many genomes, but the underlying cause of this bias has not been well established. Here we focus on the patterns of rarely-used synonymous codons. A novel method was introduced to identify the rare codons merely by codon pair bias in Escherichia coli.     

Isolation of an <Emphasis Type="Italic">Escherichia coli</Emphasis> K4 <Emphasis Type="Italic">kfoC</Emphasis> mutant over-producing capsular chondroitin

Background  

Chondroitin sulphate is a complex polysaccharide having important structural and protective functions in animal tissues. Extracted from animals, this compound is used as a human anti-inflammatory drug. Among bacteria, Escherichia coli K4 produces a capsule containing a non-sulphate chondroitin and its development may provide an efficient and cheap fermentative production of the polysaccharide.