Spontaneous reactivation of Shiga toxins in Escherichia coli O157:H7 cells caused by transposon excision

• Published in: Journal of bioscience and bioengineering Vol. 92; no. 2; pp. 114 - 120
• Main Authors: Kusumoto, Masahiro, Okitsu, Tadayuki, Nishiya, Yoshiaki, Suzuki, Rieko, Yamai, Shiro, Kawamura, Yoshihisa
• Format: Journal Article
• Language: English
• Published: Amsterdarm Elsevier B.V 2001; Elsevier Science
• Subjects: Bacteriology; Biological and medical sciences; ESCHERICHIA COLI; Escherichia coli O157:H7; Fundamental and applied biological sciences. Psychology; GENES; Genetics; insertion sequence; Microbiology; PATHOGENS; Shiga toxin gene; TOXINS; transposon; transposon; insertion sequence; Escherichia coli O157:H7; Shiga toxin gene; Toxin; Excision; Escherichia coli; Transposon; Pathogen strain; Bacteria; Transposable element; Inactivation; Enterobacteriaceae; IS element
• ISSN: 1389-1723; 1347-4421
• DOI: 10.1016/S1389-1723(01)80210-3

IS
1203v is an insertion sequence which has been found in inactivated Shiga toxin 2 genes (
stx2) of
Escherichia coli O157:H7. Using PCR amplification, we detected the wild-type
stx2 genes in colonies of
E. coli O157:H7 which possessed
stx2 genes inactivated by insertion of IS
1203v. This suggests that IS
1203v is excised from the inactivated
stx2 genes in
E. coli O157:H7. We isolated the cells possessing the wild-type
stx2 genes, and confirmed Stx2 productivities by reversed passive latex agglutination. We also analyzed the frequency of the appearance of the Stx2-producing cells using a quantitative PCR method. As a result, the frequency was 3.00 × 10
−6 with culturing for 24 h at 37°C, and this increased to 8.83 × 10
−5 when
E. coli O157:H7 possessing the inactivated
stx2 genes was transformed by an expression plasmid harboring the IS
1203v transposase. These results showed that some Stx2-nonproducing
E. coli O157:H7 strains could be spontaneously changed into Stx2-producing cells.