Functional characterization of type III secretion apparatus STM1410 encoded by Salmonella pathogenicity island 2

点击翻译按钮获取中文摘要

The virulence of many Gram-negative pathogens is associated with type III secretion systems(T3SSs), which deliver virulence effector proteins into the cytoplasm of host cells. Components of Salmonella T3SS are encoded within Salmonella pathogenicity island I and II(SPI-1 and SPI-2). While most SPI-2 T3SS proteins in Salmonella have assigned names and functions, a few of them remain poorly characterized. Here, we studied a SPI-2-encoded protein, STM1410, that shows no homology to other T3SS/flagellar proteins and is only present in pathogenic Salmonella. Our findings demonstrated that it is essential for type III secretion and that it is localized to the inner membrane. Interestingly, we found STM1410 is critical for the stability for the SPI-2 effector protein Pip B. Overall, our findings suggest that STM1410 is a structural protein that contributes to the function of the T3S complex, and therefore we propose to rename it Ssa W.