Crystal Structure of the Minor Pilin CofB, the Initiator of CFA/III Pilus Assembly in Enterotoxigenic Escherichia coli.

摘要: Type IV pili are extracellular polymers of the major pilin subunit. These subunits held together in pilus filament by hydrophobic interactions among their N-terminal α-helices, which also anchor inner membrane prior to assembly. assembly involves a conserved group proteins that span envelope Gram-negative bacteria. Among these is set minor pilins, so named because they share polymerization/membrane segment with pilins but much less abundant. Minor influence and retraction, precise functions not well defined. The systems enterotoxigenic Escherichia coli Vibrio cholerae simplest possess only single pilin. Here we show E. CofB LngB required for respective pili, CFA/III Longus. Low levels optimal assembly, can be detected fraction. We solved 2.0 A crystal structure N-terminally truncated CofB, revealing pilin-like protein an extended C-terminal region composed two discrete domains connected flexible linkers. initiate propose model CofB-initiated implications understanding growth more complex as related II secretion system.