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

TitleStructural and functional studies on the interaction of GspC and GspD in the type II secretion system.
Publication TypeJournal Article
Year of Publication2011
AuthorsKorotkov, K. V., T. L. Johnson, M. G. Jobling, J. Pruneda, E. Pardon, A. Héroux, S. Turley, J. Steyaert, R. K. Holmes, M. Sandkvist, and W. G. J. Hol
JournalPLoS Pathog
Date Published2011 Sep
KeywordsAmino Acid Sequence, Bacterial Proteins, Bacterial Secretion Systems, Cloning, Molecular, Gene Expression Regulation, Bacterial, Genes, Bacterial, Membrane Proteins, Molecular Sequence Data, Mutation, Peptide Hydrolases, Protein Structure, Tertiary, Sequence Analysis, DNA, Two-Hybrid System Techniques, Vibrio cholerae

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.

Alternate JournalPLoS Pathog.
PubMed ID21931548
PubMed Central IDPMC3169554
Grant ListAI049294 / AI / NIAID NIH HHS / United States
AI31940 / AI / NIAID NIH HHS / United States
AI34501 / AI / NIAID NIH HHS / United States
P41RR001209 / RR / NCRR NIH HHS / United States
R01 AI034501 / AI / NIAID NIH HHS / United States