The Chlamydia Type III Secretion System C-ring Engages a Chaperone-Effector Protein Complex

PLoS Pathogens

Yi-Shan Chen¹  Raphael H. Valdivia¹  Kris E. Spaeth¹ 

[1]Department of Molecular Genetics and Microbiology and Center for Microbial Pathogenesis, Duke University Medical Center, Durham, North Carolina, United States of America

关键词: Chlamydia;    Chlamydia trachomatis;    Integral membrane proteins;    Membrane proteins;    Protein secretion;    Secretion systems;    Chlamydia infection;    Protein-protein interactions;   

DOI  :  10.1371/journal.ppat.1000579

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

In Gram-negative bacterial pathogens, specialized chaperones bind to secreted effector proteins and maintain them in a partially unfolded form competent for translocation by type III secretion systems/injectisomes. How diverse sets of effector-chaperone complexes are recognized by injectisomes is unclear. Here we describe a new mechanism of effector-chaperone recognition by the Chlamydia injectisome, a unique and ancestral line of these evolutionarily conserved secretion systems. By yeast two-hybrid analysis we identified networks of Chlamydia-specific proteins that interacted with the basal structure of the injectisome, including two hubs of protein-protein interactions that linked known secreted effector proteins to CdsQ, the putative cytoplasmic C-ring component of the secretion apparatus. One of these protein-interaction hubs is defined by Ct260/Mcsc (Multiple cargo secretion chaperone). Mcsc binds to and stabilizes at least two secreted hydrophobic proteins, Cap1 and Ct618, that localize to the membrane of the pathogenic vacuole (“inclusion”). The resulting complexes bind to CdsQ, suggesting that in Chlamydia, the C-ring of the injectisome mediates the recognition of a subset of inclusion membrane proteins in complex with their chaperone. The selective recognition of inclusion membrane proteins by chaperones may provide a mechanism to co-ordinate the translocation of subsets of inclusion membrane proteins at different stages in infection.

【 授权许可】

CC BY