title: SipB-SipC complex is essential for translocon formation.
abstract: The delivery of effector proteins by Salmonella across the host cell membrane requires a subset of effectors secreted by the type III secretion system (TTSS) known as translocators. SipC and SipB are translocator proteins that are inserted into host membranes and presumably form a channel that translocates type III effectors into the host cell. The molecular events of how these translocators insert into the host cell membrane remain unknown. We have previously shown that the SipC C-terminal amino acid region (321-409) is required for the translocation of effectors into host cells. In this study, we demonstrate that the ability to form SipC-SipB complex is essential for their insertion into the host membrane. The SipB-interacting domain of SipC is near its C-terminal amino acid region (340-409). In the absence of SipB, SipC was not detected in the membrane fraction. Furthermore, SipC mutants that no longer interact with SipB are defective in inserting into the host cell membrane. We propose a mechanism whereby SipC binds SipB through its C-terminal region to facilitate membrane-insertion and subsequent translocon formation in the host cell membrane.
authors.affiliation: Department of Biological Sciences, Purdue University, West Lafayette, Indiana, United States of America.
authors.forename: Sebenzile K
authors.initials: SK
authors.lastname: Myeni
authors.forename: Lu
authors.initials: L
authors.lastname: Wang
authors.forename: Daoguo
authors.initials: D
authors.lastname: Zhou
mesh_terms: D000818:Animals; D001426:Bacterial Proteins / Q000378:metabolism*; D002462:Cell Membrane / Q000378:metabolism; D057809:HEK293 Cells; D006367:HeLa Cells; D054884:Host-Pathogen Interactions; D006801:Humans; D008565:Membrane Proteins / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism; D050505:Mutant Proteins / Q000737:chemistry / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D011485:Protein Binding; D021381:Protein Transport; D012480:Salmonella Infections / Q000378:metabolism; D012486:Salmonella typhimurium / Q000378:metabolism; D012756:Sheep; D013329:Structure-Activity Relationship
chemical_list: D001426:Bacterial Proteins; D008565:Membrane Proteins; D018832:Molecular Chaperones; D050505:Mutant Proteins; C094578:Salmonella invasion protein C; C094579:invasion protein B, Salmonella typhimurium
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