Homologs of the Shigella IpaB and IpaC invasins are required for Salmonella typhimurium entry into cultured epithelial cells.
Entry into host cells is an essential feature in the pathogenicity of Salmonella spp. The inv locus of Salmonella typhimurium encodes several proteins which are components of a type III protein secretion system required for these organisms to gain access to host cells. We report here the identification of several proteins whose secretion into the culture supernatant of S. typhimurium is dependent on the function of the inv-encoded translocation apparatus. Nucleotide sequence analysis of the genes encoding two of these secreted proteins, SipB and SipC, indicated that they are homologous to the Shigella sp. invasins IpaB and IpaC, respectively. An additional gene was identified, sicA, which encodes a protein homologous to IpgC, a Shigella protein that serves as a molecular chaperone for the invasins IpaB and IpaC. Nonpolar mutations in sicA, sipB, and sipC rendered S. typhimurium unable to enter cultured epithelial cells, indicating that these genes are required for bacterial internalization.
Kaniga
K
K
Department of Molecular Genetics and Microbiology, School of Medicine, State University of New York at Stony Brook 11794-5222, USA.
Tucker
S
S
Trollinger
D
D
Galán
J E
JE
D000595:Amino Acid Sequence; D000942:Antigens, Bacterial / Q000235:genetics; D001426:Bacterial Proteins / Q000235:genetics* / Q000378:metabolism; D001692:Biological Transport; D002478:Cells, Cultured; D003001:Cloning, Molecular; D004847:Epithelial Cells; D004848:Epithelium / Q000382:microbiology; D008565:Membrane Proteins / Q000378:metabolism; D018832:Molecular Chaperones / Q000235:genetics*; D008969:Molecular Sequence Data; D015183:Restriction Mapping; D012486:Salmonella typhimurium / Q000235:genetics* / Q000472:pathogenicity*; D017422:Sequence Analysis, DNA; D017386:Sequence Homology, Amino Acid; D012760:Shigella / Q000235:genetics; D014774:Virulence / Q000235:genetics
D000942:Antigens, Bacterial; D001426:Bacterial Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; C094578:Salmonella invasion protein C; C094577:SicA protein, Salmonella typhimurium; C094579:invasion protein B, Salmonella typhimurium; C087447:ipaB protein, Shigella; C092342:IpaC protein, Shigella; C094580:IpgC protein, Shigella