1l4i
From Proteopedia
Crystal Structure of the Periplasmic Chaperone SfaE
Overview
S pili are sialic acid binding hair-like appendages expressed by pathogenic strains of Escherichia coli. The presence of S pili has been implicated as a virulence factor in both urinary-tract infections and new-born meningitis. Assembly of S pili proceeds via the ubiquitous chaperone/usher pathway. Previously, structures of the homologous chaperones PapD and FimC involved in assembly of P and type-1 pili, respectively, have been solved. Here, the 2.2 A X-ray structure of the S pilus chaperone SfaE is reported. SfaE has the same overall L-shaped structure as PapD and FimC, with two immunoglobulin-like domains oriented at about a 90 degrees angle to each other. Conserved residues in the subunit-binding cleft known to be critical for chaperone function occupy essentially identical positions in SfaE, FimC and PapD. As in free PapD and FimC, the long F1-G1 loop connecting the two last strands of the N-terminal domain is disordered. SfaE crystallizes as a dimer with an extensive dimer interface involving the subunit-binding surfaces of the chaperone. Dimerization via these regions has previously been observed for PapD and might be a general side effect arising from the subunit-binding properties of periplasmic chaperones. The domain interface contains an extended hydrogen-bond network involving three invariant charged residues and two structurally conserved water molecules. It is suggested that disruption of the domain interactions may destabilize the N-terminal domain through exposure of three conserved hydrophobic residues, thereby promoting release of pilus subunits during pilus assembly.
About this Structure
1L4I is a Single protein structure of sequence from Escherichia coli. Full crystallographic information is available from OCA.
Reference
Structure of the S pilus periplasmic chaperone SfaE at 2.2 A resolution., Knight SD, Choudhury D, Hultgren S, Pinkner J, Stojanoff V, Thompson A, Acta Crystallogr D Biol Crystallogr. 2002 Jun;58(Pt 6 Pt 2):1016-22. Epub, 2002 May 29. PMID:12037304 Page seeded by OCA on Fri May 2 23:32:00 2008
