Many bacterial pathogens encode ADP-ribosyltransferase toxins. We identified an ADP-ribosyltransferase toxin homologue (ArtA, ArtB) in Salmonella enterica serovar Typhimurium (S. typhimurium) DT104. ArtA is most homologous to a putative pertussis-like toxin subunit present in S. typhi (STY1890) and S. paratyphi A (SPA1609), while ArtB shows homology to a hypothetical periplasmic protein of S. typhi (STY1364) and S. paratyphi A (SPA1188) and to a putative pertussis-like toxin subunit in S. typhi (STY1891) and S. paratyphi A (SPA1610). The artA gene was detected from the phage particle fraction upon mitomycin C induction, and the flanking region of artAB contains a prophage-like sequence, suggesting that these putative toxin genes reside within a prophage. Southern blotting analysis revealed that artA is conserved in twelve confirmed strains and in the four related strains of DT104 which are classified into the same group as DT104 by both amplified-fragment length polymorphism and pulsed-field gel electrophoresis. Except for one strain, NCTC73, all 13 S. typhimurium strains which were classified into different groups from that of DT104 lacked the artA locus. Our presented results suggest that phage-mediated recombination has resulted in the acquisition of art genes in the S. typhimurium DT104 strains.
(Research Team for Environmental/Enzootic Disease, Hokkaido Research Station, TEL +81-11-851-5226)
Reference:
Saitoh et al. (2005) Microbiology 151, 3089-3096.
