Identification and Characterization of a Newly Isolated Shiga Toxin 2-Converting Phage from Shiga Toxin-ProducingEscherichia coli

Abstract

Science 226: [694][695][696] 1984). In this study, we isolated two Stx2-converting phages, designated Stx2⌽-I and Stx2⌽-II, from two clinical strains of STEC associated with the outbreaks in Japan in 1996 and found that Stx2⌽-I resembled 933W, the previously reported Stx2-converting phage, in its infective properties for E. coli K-12 strain C600 while Stx2⌽-II was distinct from them. The sizes of the plaques of Stx2⌽-I and Stx2⌽-II in C600 were different; the former was larger than the latter. The restriction maps of Stx2⌽-I and Stx2⌽-II were not identical; rather, Stx2⌽-II DNA was approximately 3 kb larger than Stx2⌽-I DNA. Furthermore, Stx2⌽-I and Stx2⌽-II showed different phage immunity, with Stx2⌽-I and 933W belonging to the same group. Infection of C600 by Stx2⌽-I or 933W was affected by environmental osmolarity differently from that by Stx2⌽-II. When C600 was grown under conditions of high osmolarity, the infectivity of Stx2⌽-I and 933W was greatly decreased compared with that of Stx2⌽-II. Examination of the plating efficiency of the three phages for the defined mutations in C600 revealed that the efficiency of Stx2⌽-I and 933W for the fadL mutant decreased to less than 10 ؊7 compared with that for C600 whereas the efficiency of Stx2⌽-II decreased to 0.1% of that for C600. In contrast, while the plating efficiency of Stx2⌽-II for the lamB mutant decreased to a low level (0.05% of that for C600), the efficiencies of Stx2⌽-I and 933W were not changed. This was confirmed by the phage neutralization experiments with isolated outer membrane fractions from C600, fadL mutant, or lamB mutant or the purified His 6 -tagged FadL and LamB proteins. Based on the data, we concluded that FadL acts as the receptor for Stx2⌽-I and Stx2⌽-II whereas LamB acts as the receptor only for Stx2⌽-II.

Isogenic Lysogens of Diverse Shiga Toxin 2-Encoding Bacteriophages Produce Markedly Different Amounts of Shiga Toxin

“…67, 1999 NOTES 6711 ongoing recombination within the lambdoid phage gene pool (reviewed in reference 10). Differences between Stx2-encoding phages from serotype O157 STEC isolates have been reported (6,22). Our results extend these findings to include Stx2-encoding phages derived from STEC of various serotypes, including O157, O145, O111, and O83.…”

“…Significant genomic divergence among Stx1-encoding phages isolated from different E. coli serotypes has been dem-onstrated by analysis of phage genome lengths and restriction fragment length polymorphisms (RFLP) (25). Recent studies have revealed some variation within O157-derived Stx2-encoding phages (6,22). In the present study, to assess the level of variation among Stx2-encoding phages derived from multiple STEC serotypes and its possible relevance to toxin regulation, we produced isogenic lysogens of seven different Stx2-encoding phages.…”

Spontaneous tandem amplification and deletion of the Shiga toxin operon in Shigella dysenteriae 1

“…The receptors for certain Stx2-converting bacteriophages in E. coli have been recently elucidated. They are the maltose-inducible outer membrane protein, LamB, which serves as the lambda receptor, and the outer membrane protein, FadL, involved in long-chain fatty acid transport (Watarai et al, 1998). S. dysenteriae 1 strains 60R and 60RchlorR1 and S. flexneri strains 2457T and M90T were therefore grown with added maltose to induce the lambda receptor (Watarai et al, 1998), then incubated with purified H19BCmR bacteriophage (see Experimental procedures).…”

Non-pathogenic Escherichia coli Enhance Stx2a Production of E. coli O157:H7 Through Both bamA-Dependent and Independent Mechanisms

“…The progeny stx -converting phages may infect other E. coli strains after adsorbing to the outer membrane proteins including BamA (Watarai et al, 1998 ; Smith et al, 2007 ). BamA is essential for outer membrane protein biogenesis (Wu et al, 2005 ) and exists in all members of the Enterobacteriaceae family.…”