An Escherichia coli Reference Collection Group B2- and Uropathogen-Associated Polymorphism in the rpoS-mutS Region of the E. coli Chromosome

Abstract

Chromosomal DNAs of enterohemorrhagic, uropathogenic, and laboratory attenuated Escherichia coli strains differ in the rpoS-mutS region. Many uropathogens lack a deletion and an insertion characteristic of enterohemorrhagic strains. At the same chromosomal position, they harbor a 2.1-kb insertion of unknown origin with a base composition suggestive of horizontal gene transfer. Unlike virulence determinants associated with urinary tract infection and/or neonatal meningitis (pap or prs, sfa, kps, and hly), the 2.1-kb insertion is shared by all group B2 strains of the E. coli Reference Collection.Genomic sequencing offers unprecedented opportunities for the identification of genetic polymorphisms related to bacterial evolution and virulence. The complete nucleotide sequence of Escherichia coli MG1655 (4), a representative laboratory-attenuated E. coli K-12 strain, provides a foundation for studies of the evolution and virulence of E. coli strains associated with diverse pathologies. The expanding list of E. coli virotypes includes diverse diarrheagenic organisms (labeled enterotoxigenic, enteropathogenic, enterohemorrhagic, enteroaggregative, enteroinvasive, and diffusely adherent) (28) as well as isolates associated with extraintestinal diseases, including neonatal meningitis (7) and urinary tract infections (UTIs) (including bacteriuria, cystitis, and pyelonephritis) (11). By complementing phenotypic analysis and multilocus enzyme electrophoresis, sequence comparisons are now providing profound insights into the pathogenesis and evolution of E. coli (5, 12, 19, 23-25, 28, 29, 37, 39-42). These and other studies (13,15) reveal that the chromosomal DNA sequences of modern organisms reflect both their clonal origins and horizontal gene transfer.A uropathogen-associated, rpoS-proximal DNA polymorphism in E. coli. Recently, LeClerc et al. (21) reported that, in comparison to E. coli MG1655, E. coli O157:H7, related enterohemorrhagic E. coli strains, and Shigella dysenteriae lack 6

Extended Virulence Genotype of Pathogenic Escherichia coli Isolates Carrying the afa-8 Operon: Evidence of Similarities between Isolates from Humans and Animals with Extraintestinal Infections

“…In comparison to E. coli MG1655, previous studies (14,21,39) revealed that EPEC, EHEC, and E. coli group B2 strains harbor specific DNA insertions within the mutS-rpoS intergenic region. A PCR assay was developed to determine the nature of the mutS-rpoS intergenic region of the afa-8 isolates.…”

The osmotic stress response and virulence in pyelonephritis isolates of Escherichia coli: contributions of RpoS, ProP, ProU and other systems The GenBank accession numbers for the DNA sequences of the rpoS loci in E. coli strains HU734 and CFT073 are AF275947 and AF270497, respectively.

“…The DNA sequences of the rpoS loci in strains HU734 and CFT073 were determined as described by Culham & Wood (2000).…”

“…PCR amplification and DNA sequence analysis revealed that the rpoS gene is present in both HU734 and CFT073 (see Methods). In comparison with E. coli K-12, both harboured a DNA insertion downstream from rpoS (Culham & Wood, 2000) as well as single base changes within rpoS. One single base change would create an amino acid change within RpoS (Q45E).…”

Signal Transduction and Regulatory Mechanisms Involved in Control of the σS(RpoS) Subunit of RNA Polymerase

“…A region covering most of stem-loop 1 and the following single-stranded part of DsrA is complementary to an upstream "antisense element" in rpoS mRNA that is assumed to base pair with the TIR region, suggesting that DsrA functions by an "anti-antisense" mechanism that disrupts intramolecular basepairing in rpoS mRNA (119,120,131). DsrA plays only a minor role for rpoS translation in cells grown at 37 or 42°C yet becomes the major stimulating factor at 30°C and especially at 20°C (199). The basis of low-temperature translational induction of S is the clearly enhanced transcription of dsrA as well as a sixfoldincreased stability of DsrA at low temperature (177).…”

“…Downstream of rpoS, however, variations are quite common and even occur between different E. coli strains (28,37,83). However, nlpD can occur alone in bacteria that do not possess an rpoS gene, such as Haemophilus influenzae (55).…”