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.
Highlights
Many gram negative bacterial pathogens utilize type three secretion systems (TTSS) to translocate virulence factors into host cells to exploit host-cell functions for their own benefit
The transport of bacterial effector proteins across the host cell membrane is facilitated by a subset of Salmonella effector proteins that are known as translocators: SipB, SipC, and SipD
The delivery of Salmonella type III effector proteins across the host cell membrane requires the formation of the translocon by SipB, SipC, and SipD
Summary
Many gram negative bacterial pathogens utilize type three secretion systems (TTSS) to translocate virulence factors into host cells to exploit host-cell functions for their own benefit. The transport of bacterial effector proteins across the host cell membrane is facilitated by a subset of Salmonella effector proteins that are known as translocators: SipB, SipC, and SipD. SipB, SipC and SipD, are required to form functional pores during Salmonella infection of erythrocytes [15]. The intimate attachment of Salmonella with host cells is believed to trigger the TTSS while the insertion of SipC and SipB into membranes and pore formation are conceived to be important for protein translocation into host cells. It was speculated that the SipB-SipC complex is important for the channel formation and the translocation of effectors into the host cell. We present evidence that the complex formation between SipC and SipB is essential for the insertion of both proteins into the host cell membrane during Salmonella invasion. We propose a mechanism whereby SipC binds SipB through its Cterminal region to facilitate subsequent translocon formation
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
