Crystal structure of the C‐terminal domain of the Salmonella type III secretion system export apparatus protein InvA

InvA is a prominent inner‐membrane component of the Salmonella type III secretion system (T3SS) apparatus, which is responsible for regulating virulence protein export in pathogenic bacteria. InvA is made up of an N‐terminal integral membrane domain and a C‐terminal cytoplasmic domain that is proposed to form part of a docking platform for the soluble export apparatus proteins notably the T3SS ATPase InvC. Here, we report the novel crystal structure of the C‐terminal domain of Salmonella InvA which shows a compact structure composed of four subdomains. The overall structure is unique although the first and second subdomains exhibit structural similarity to the peripheral stalk of the A/V‐type ATPase and a ring building motif found in other T3SS proteins respectively.