Structural and Functional Studies on the Interaction of GspC and GspD in the Type II Secretion System

PLoS Pathogens

Konstantin V. Korotkov¹  Jan Steyaert¹  Jonathan Pruneda¹  Tanya L. Johnson²  Wim G. J. Hol³  Michael G. Jobling³  Randall K. Holmes⁴  Els Pardon⁴  Stewart Turley⁵  Maria Sandkvist⁶  Annie Héroux⁶ 

[1] Department of Biochemistry, Biomolecular Structure Center, University of Washington, Seattle, Washington, United States of America;Department of Microbiology and Immunology, University of Michigan Medical School, Ann Arbor, Michigan, United States of America;Department of Microbiology, University of Colorado School of Medicine, Aurora, Colorado, United States of America;Department of Molecular and Cellular Interactions, VIB, Brussels, Belgium;National Synchrotron Light Source, Brookhaven National Laboratory, Upton, New York, United States of America;Structural Biology Brussels, Vrije Universiteit Brussel, Brussels, Belgium

关键词: Crystal structure;    Vibrio cholerae;    Secretion systems;    Secretin;    Outer membrane proteins;    Crystals;    Proteases;    Protein structure;   

DOI  :  10.1371/journal.ppat.1002228

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

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 (GspCHR) in complex with either two or three domains of the N-terminal region of GspD from enterotoxigenic Escherichia coli show that GspCHR 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 GspCHR–GspDN0 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.

【 授权许可】

CC BY