title: Host-dependent activation of IS1203v excision in Shiga toxin-producing Escherichia coli.
abstract: IS1203v is an insertion sequence (IS) which is identical to the most abundant IS elements in the genome of Escherichia coli O157:H7. However, there is no sequence homologous to IS1203v in the genome of E. coli K-12. We constructed a system to analyze the excision frequency of IS1203v, and demonstrated that the frequency in E. coli O157:H7 was approximately 10(5) times higher than that in E. coli K-12. We also investigated the excision frequencies of IS1203v in various E. coli isolates, and showed that the excision frequencies of IS1203v-possessing strains were approximately 10(3) times higher than those of IS1203v-nonpossessing strains. The results suggest that the IS1203v-possessing strains use a common system to enhance IS1203v excision.
authors.affiliation: Tsuruga Institute of Biotechnology, Toyobo Co. Ltd., 10-24 Toyo-cho, Tsuruga, Fukui 914-0047, Japan. masahiro_kusumoto@bio.toyobo.co.jp
authors.forename: Masahiro
authors.initials: M
authors.lastname: Kusumoto
authors.forename: Rieko
authors.initials: R
authors.lastname: Suzuki
authors.forename: Yoshiaki
authors.initials: Y
authors.lastname: Nishiya
authors.forename: Tadayuki
authors.initials: T
authors.lastname: Okitsu
authors.forename: Masanori
authors.initials: M
authors.lastname: Oka