Structure of CfaA Suggests a New Family of Chaperones Essential for Assembly of Class 5 Fimbriae

PLoS Pathogens

Di Xia¹  Stephen J. Savarino²  Annette McVeigh²  April Fordyce²  Yu-Xing Chen³  Rui Bao⁴ 

[1] Department of Pediatrics, Uniformed Services University of the Health Sciences, Bethesda, Maryland, United States of America;Enteric Diseases Department, Infectious Diseases Directorate, Naval Medical Research Center, Silver Spring, Maryland, United States of America;Hefei National Laboratory for Physical Sciences at Microscale and School of Life Sciences, University of Science and Technology of China, Hefei, Anhui, People's Republic of China;Laboratory of Cell Biology, Center for Cancer Research, National Cancer Institute, National Institutes of Health, Bethesda, Maryland, United States of America

关键词: Pili;    fimbriae;    Sequence alignment;    Crystal structure;    Sequence motif analysis;    Insertion mutation;    Centrifugation;    Disulfide bonds;    Protein structure databases;   

DOI  :  10.1371/journal.ppat.1004316

学科分类：生物科学（综合）

来源: Public Library of Science

【 摘 要 】

Adhesive pili on the surface of pathogenic bacteria comprise polymerized pilin subunits and are essential for initiation of infections. Pili assembled by the chaperone-usher pathway (CUP) require periplasmic chaperones that assist subunit folding, maintain their stability, and escort them to the site of bioassembly. Until now, CUP chaperones have been classified into two families, FGS and FGL, based on the short and long length of the subunit-interacting loops between its F1 and G1 β-strands, respectively. CfaA is the chaperone for assembly of colonization factor antigen I (CFA/I) pili of enterotoxigenic E. coli (ETEC), a cause of diarrhea in travelers and young children. Here, the crystal structure of CfaA along with sequence analyses reveals some unique structural and functional features, leading us to propose a separate family for CfaA and closely related chaperones. Phenotypic changes resulting from mutations in regions unique to this chaperone family provide insight into their function, consistent with involvement of these regions in interactions with cognate subunits and usher proteins during pilus assembly.

【 授权许可】

CC BY