The Salmonella type III secretion translocon protein SspC is inserted into the epithelial cell plasma membrane upon infection.
Salmonella species translocate effector proteins into the host cell cytoplasm using a type III secretion system (TTSS). The translocation machinery probably contacts the eukaryotic cell plasma membrane to effect protein transfer. Data presented here demonstrate that both SspB and SspC, components of the translocation apparatus, are inserted into the epithelial cell plasma membrane 15 min after Salmonella typhimurium infection. In addition, a yeast two-hybrid interaction between SspC and an eukaryotic intermediate filament protein was identified. Three individual carboxyl-terminal point mutations within SspC that disrupt the yeast two-hybrid interaction were isolated. Strains expressing the mutant SspC alleles were defective for invasion, translocation of effector molecules and membrane localization of SspC. These data indicate that insertion of SspC into the plasma membrane of target cells is required for invasion and effector molecule translocation and that the carboxyl terminus of SspC is essential for these functions.
Scherer
C A
CA
Departments of Microbiology and Medicine, University of Washington, Box 357710, Seattle, WA 98195-7710, USA.
Cooper
E
E
Miller
S I
SI
D001426:Bacterial Proteins / Q000235:genetics / Q000378:metabolism*; D001692:Biological Transport; D002458:Cell Fractionation; D002462:Cell Membrane / Q000378:metabolism; D004847:Epithelial Cells / Q000378:metabolism / Q000382:microbiology; D015870:Gene Expression; D006367:HeLa Cells; D006801:Humans; D007633:Keratins / Q000235:genetics / Q000378:metabolism; D008565:Membrane Proteins / Q000378:metabolism; D017354:Point Mutation; D012486:Salmonella typhimurium / Q000235:genetics / Q000378:metabolism* / Q000472:pathogenicity; D013997:Time Factors; D020798:Two-Hybrid System Techniques
D001426:Bacterial Proteins; D008565:Membrane Proteins; C094578:Salmonella invasion protein C; C094579:invasion protein B, Salmonella typhimurium; D007633:Keratins