title: Genetic variation in the flanking regions of Shiga toxin 2 gene in Shiga toxin-producing Escherichia coli O157:H7 isolated in Japan.
abstract: We found frequent IS1 integration nearby the stx(2) gene during in vitro mutagenesis of an stx(2) variant, stx(2vhd). To examine the possibility that such insertions have been contributing to generate new stx(2) variants, we screened 86 strains of Escherichia coli O157:H7 isolated in Japan for variations in the ca. 4-kb region flanking the stx(2) locus using PCR methods. Two major classes were identified based on the PCR amplicon size. DNA sequence analysis revealed that the stx(2) subtype of the two classes were stx(2) (referred to as stx(2-EDL933)) and stx(2vhd). IS1203v insertions were found in three stx(2vhd)-positive strains and two stx(2-EDL933)-positive strains, and no other insertions were found. These results suggest that the DNA sequences surrounding the stx(2) genes are preferably integrated by IS1203v in wild-type Shiga toxin-producing E. coli strains.
authors.affiliation: Research Institute, International Medical Center of Japan, 1-21-1 Toyama, Shinjuku, Tokyo 162-8655, Japan. thama@ri.imcj.go.jp
authors.forename: Takashi
authors.initials: T
authors.lastname: Hamabata
authors.forename: Tetsuya
authors.initials: T
authors.lastname: Tanaka
authors.forename: Ayako
authors.initials: A
authors.lastname: Ozawa
authors.forename: Tatsuichiro
authors.initials: T
authors.lastname: Shima
authors.forename: Toshio
authors.initials: T
authors.lastname: Sato
authors.forename: Yoshifumi
authors.initials: Y
authors.lastname: Takeda
mesh_terms: D015139:Blotting, Southern; D004251:DNA Transposable Elements / Q000235:genetics*; D004927:Escherichia coli Infections / Q000821:virology; D019453:Escherichia coli O157 / Q000235:genetics*; D014644:Genetic Variation; D006801:Humans; D016297:Mutagenesis, Site-Directed; D016133:Polymerase Chain Reaction; D017422:Sequence Analysis, DNA; D022621:Shiga Toxin / Q000096:biosynthesis*; D022641:Shiga Toxin 2 / Q000737:chemistry / Q000235:genetics*
chemical_list: D004251:DNA Transposable Elements; D022641:Shiga Toxin 2; D022621:Shiga Toxin