Identification of a pathogenicity island required for Salmonella survival in host cells.
We have identified a region unique to the Salmonella typhimurium chromosome that is essential for virulence in mice. This region harbors at least three genes: two (spiA and spiB) encode products that are similar to proteins found in type III secretion systems, and a third (spiR) encodes a putative regulator. A strain with a mutation in spiA was unable to survive within macrophages but displayed wild-type levels of epithelial cell invasion. The culture supernatants of the spi mutants lacked a modified form of flagellin, which was present in the supernatant of the wild-type strain. This suggests that the Spi secretory apparatus exports a protease, or a protein that can alter the activity of a secreted protease. The "pathogenicity island" harboring the spi genes may encode the virulence determinants that set Salmonella apart from other enteric pathogens.
Ochman
H
H
Department of Biology, University of Rochester, NY 14627, USA.
Soncini
F C
FC
Solomon
F
F
Groisman
E A
EA
D000595:Amino Acid Sequence; D000818:Animals; D001426:Bacterial Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000235:genetics*; D002460:Cell Line; D002470:Cell Survival; D010450:Endopeptidases / Q000378:metabolism; D005408:Flagellin / Q000235:genetics; D005798:Genes, Bacterial; D008264:Macrophages / Q000166:cytology / Q000382:microbiology*; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D012486:Salmonella typhimurium / Q000235:genetics* / Q000254:growth & development / Q000472:pathogenicity*; D017386:Sequence Homology, Amino Acid; D014774:Virulence / Q000235:genetics*
D001426:Bacterial Proteins; C101486:SpiA protein, Salmonella typhimurium; D005408:Flagellin; D010450:Endopeptidases