Abstract
BackgroundType III secretion systems (T3SS) are essential virulence factors of most Gram-negative bacterial pathogens. T3SS deliver effector proteins directly into the cytoplasm of eukaryotic target cells and for this function, the insertion of a subset of T3SS proteins into the target cell membrane is important. These proteins form hetero-oligomeric pores acting as translocon for the delivery of effector proteins. Salmonella enterica is a facultative intracellular pathogen that uses the Salmonella Pathogenicity Island 2 (SPI2)-encoded T3SS to manipulate host cells in order to survive and proliferate within the Salmonella-containing vacuole of host cells. Previous work showed that SPI2-encoded SseB, SseC and SseD act to form the translocon of the SPI2-T3SS.ResultsHere we investigated the structural requirements of SseB and SseD to form a functional translocon. Based on bioinformatic predictions, deletional analyses of SseB and SseD were performed and the effect on secretion by the T3SS, formation of a translocon, translocation of effector proteins and intracellular replication was investigated. Our data showed that both SseB and SseD are very sensitive towards alterations of the primary structure of the proteins. Although proteins encoded by mutant alleles were still secreted, we observed that all mutations resulted in a loss of function of the SPI2-T3SS.ConclusionThese observations indicate that translocon proteins of the SPI2-T3SS are highly evolved towards the formation of multi-subunit complex in the host cell membrane. Structural alterations are not tolerated and abrogate translocon function.
Highlights
Type III secretion systems (T3SS) are essential virulence factors of most Gram-negative bacterial pathogens
Type III secretion systems (T3SS) and type IV secretion systems are of specific interest since these systems mediate the vectorial transport of effector proteins into eukaryotic target cells [reviewed in [1]]
Deletional analyses of translocon proteins SseB and SseD Based on the previous observation that SseB, SseC and SseD are required for the translocation of effector proteins by intracellular Salmonella [7], we started deletional analyses for the identification of functionally essential domains of the proteins
Summary
Type III secretion systems (T3SS) are essential virulence factors of most Gram-negative bacterial pathogens. T3SS deliver effector proteins directly into the cytoplasm of eukaryotic target cells and for this function, the insertion of a subset of T3SS proteins into the target cell membrane is important These proteins form heterooligomeric pores acting as translocon for the delivery of effector proteins. Type III secretion systems (T3SS) and type IV secretion systems are of specific interest since these systems mediate the vectorial transport of effector proteins into eukaryotic target cells [reviewed in [1]]. This process is termed translocation and requires the contact of the bacteria to a host cell membrane. Salmonella enterica is a facultative intracellular pathogen that has devel-
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.
