Structural and functional studies on the interaction of GspC and GspD in the type II secretion system.

PLoS Pathogens. 2011;7(9):e1002228 DOI 10.1371/journal.ppat.1002228

 

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Journal Title: PLoS Pathogens

ISSN: 1553-7366 (Print); 1553-7374 (Online)

Publisher: Public Library of Science (PLoS)

LCC Subject Category: Medicine: Internal medicine: Specialties of internal medicine: Immunologic diseases. Allergy | Science: Biology (General)

Country of publisher: United States

Language of fulltext: English

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AUTHORS

Konstantin V Korotkov
Tanya L Johnson
Michael G Jobling
Jonathan Pruneda
Els Pardon
Annie Héroux
Stewart Turley
Jan Steyaert
Randall K Holmes
Maria Sandkvist
Wim G J Hol

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Time From Submission to Publication: 24 weeks

 

Abstract | Full Text

Type II secretion systems (T2SSs) are critical for secretion of many proteins from Gram-negative bacteria. In the T2SS, the outer membrane secretin GspD forms a multimeric pore for translocation of secreted proteins. GspD and the inner membrane protein GspC interact with each other via periplasmic domains. Three different crystal structures of the homology region domain of GspC (GspC(HR)) in complex with either two or three domains of the N-terminal region of GspD from enterotoxigenic Escherichia coli show that GspC(HR) adopts an all-β topology. N-terminal β-strands of GspC and the N0 domain of GspD are major components of the interface between these inner and outer membrane proteins from the T2SS. The biological relevance of the observed GspC-GspD interface is shown by analysis of variant proteins in two-hybrid studies and by the effect of mutations in homologous genes on extracellular secretion and subcellular distribution of GspC in Vibrio cholerae. Substitutions of interface residues of GspD have a dramatic effect on the focal distribution of GspC in V. cholerae. These studies indicate that the GspC(HR)-GspD(N0) interactions observed in the crystal structure are essential for T2SS function. Possible implications of our structures for the stoichiometry of the T2SS and exoprotein secretion are discussed.