Chaperone-tip adhesin complex is vital for synergistic activation of CFA/I fimbriae biogenesis

Li-hui He, Hao Wang, Yang Liu, Mei Kang, Tao Li, Chang-cheng Li, Ai-ping Tong, Yi-bo Zhu, Ying-jie Song, Stephen J. Savarino, Michael G. Prouty, Di Xia (+2 others)
2020 PLoS Pathogens  
Colonization factor CFA/I defines the major adhesive fimbriae of enterotoxigenic Escherichia coli and mediates bacterial attachment to host intestinal epithelial cells. The CFA/I fimbria consists of a tip-localized minor adhesive subunit, CfaE, and thousands of copies of the major subunit CfaB polymerized into an ordered helical rod. Biosynthesis of CFA/I fimbriae requires the assistance of the periplasmic chaperone CfaA and outer membrane usher CfaC. Although the CfaE subunit is proposed to
more » ... tiate the assembly of CFA/I fimbriae, how it performs this function remains elusive. Here, we report the establishment of an in vitro assay for CFA/I fimbria assembly and show that stabilized CfaA-CfaB and CfaA-CfaE binary complexes together with CfaC are sufficient to drive fimbria formation. The presence of both CfaA-CfaE and CfaC accelerates fimbria formation, while the absence of either component leads to linearized CfaB polymers in vitro. We further report the crystal structure of the stabilized CfaA-CfaE complex, revealing features unique for biogenesis of Class 5 fimbriae.
doi:10.1371/journal.ppat.1008848 pmid:33007034 fatcat:37slyrjb75gerfoodfcprbcisa