This is the C-terminal domain of the EscN protein family of ATPases that form part of the Type III secretion system (T3SS) present in Escherichia coli. T3SS is a macromolecular complex that creates a syringe-like apparatus extending from the bacterial cytosol across three membranes to the eukaryotic cytosol. This process is essential for pathogenicity. EscN is a functionally unique ATPase that provides an inner-membrane recognition gate for the T3SS chaperone-virulence effector complexes as well as a potential source of energy for their subsequent secretion.The C-terminal domain of T3SS ATPases mediates binding with multiple contact points along the chaperone [1].

1: Structural analysis of a prototypical ATPase from the type III secretion system. Zarivach R, Vuckovic M, Deng W, Finlay BB, Strynadka NC; Nat Struct Mol Biol. 2007;14:131-137. PMID:17237797

2: Structural similarity between the flagellar type III ATPase FliI and F1-ATPase subunits. Imada K, Minamino T, Tahara A, Namba K; Proc Natl Acad Sci U S A. 2007;104:485-490. PMID:17202259