title: Gene conservation and loss in the mutS-rpoS genomic region of pathogenic Escherichia coli.
abstract: The extent and nature of DNA polymorphism in the mutS-rpoS region of the Escherichia coli genome were assessed in 21 strains of enteropathogenic E. coli (EPEC) and enterohemorrhagic E. coli (EHEC) and in 6 strains originally isolated from natural populations. The intervening region between mutS and rpoS was amplified by long-range PCR, and the resulting amplicons varied substantially in length (7.8 to 14.2 kb) among pathogenic groups. Restriction maps based on five enzymes and sequence analysis showed that strains of the EPEC 1, EPEC 2, and EHEC 2 groups have a long mutS-rpoS region composed of a approximately 6.0-kb DNA segment found in strain K-12 and a novel DNA segment ( approximately 2.9 kb) located at the 3' end of rpoS. The novel segment contains three genes (yclC, pad1, and slyA) that occur in E. coli O157:H7 and related strains but are not found in K-12 or members of the ECOR group A. Phylogenetic analysis of the common sequences indicates that the long intergenic region is ancestral and at least two separate deletion events gave rise to the shorter regions characteristic of the E. coli O157:H7 and K-12 lineages.
authors.affiliation: Institute of Molecular Evolutionary Genetics, Department of Biology, Pennsylvania State University, University Park, Pennsylvania 16802, USA.
authors.forename: C J
authors.initials: CJ
authors.lastname: Herbelin
authors.forename: S C
authors.initials: SC
authors.lastname: Chirillo
authors.forename: K A
authors.initials: KA
authors.lastname: Melnick
authors.forename: T S
authors.initials: TS
authors.lastname: Whittam
mesh_terms: D000251:Adenosine Triphosphatases; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000235:genetics*; D001483:Base Sequence; D017124:Conserved Sequence; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D004926:Escherichia coli / Q000235:genetics*; D029968:Escherichia coli Proteins; D005798:Genes, Bacterial; D016680:Genome, Bacterial; D008969:Molecular Sequence Data; D051719:MutS DNA Mismatch-Binding Protein; D011110:Polymorphism, Genetic; D017422:Sequence Analysis, DNA; D012808:Sigma Factor / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D004269:DNA, Bacterial; D004268:DNA-Binding Proteins; D029968:Escherichia coli Proteins; D012808:Sigma Factor; C069567:sigma factor KatF protein, Bacteria; D000251:Adenosine Triphosphatases; D051719:MutS DNA Mismatch-Binding Protein; C497175:MutS protein, E coli