InterPro domain: IPR038432

In addition to the PulS/OutS proteins this entry also includes other functionally uncharacterised proteins, such as YacC from Escherischia coli ( P0AA95 ).

This superfamily comprises lipoproteins from gamma proteobacterial species: pullulanase secretion protein PulS protein of Klebsiella pneumoniae ( P20440 ), the lipoprotein OutS protein of Erwinia chrysanthemi ( Q01567 ) and the functionally uncharacterised type II secretion protein EtpO ( Q7BSV3 ) from Escherichia coli O157:H7. PulS and OutS have been shown to interact with and facilitate insertion of secretins into the outer membrane, suggesting a chaperone-like, or piloting function for members of this superfamily. These proteins consist of 4 alpha helices arranged into a slightly elongated, C-shaped helical bundle. Within PulS, the helices form a binding groove which interact with a disordered region on another protein, PulD, to form a PulS-PulD complex. PulD then oligomerises into a dodecameric outer membrane complex in the formation of a type II secretion system [ 1 ].

1. Pilotin-secretin recognition in the type II secretion system of Klebsiella oxytoca. Mol Microbiol 82, 1422-32