Open AccessChaperone-tip adhesin complex is vital for synergistic activation of CFA/I fimbriae biogenesis
Author(s) -
Libang He,
Hao Wang,
Yang Liu,
Mei Kang,
Tao Li,
Changcheng Li,
Aiping Tong,
Yuanfeng Zhu,
Yingjie Song,
Stephen J. Savarino,
Michael G. Prouty,
Di Xia,
Rui Bao
Publication year - 2020
Publication title -
plos pathogens
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 3.719
H-Index - 206
eISSN - 1553-7374
pISSN - 1553-7366
DOI - 10.1371/journal.ppat.1008848
Subject(s) - fimbria , biogenesis , chaperone (clinical) , protein subunit , microbiology and biotechnology , periplasmic space , bacterial adhesin , bacterial outer membrane , pilus , biology , fimbriae proteins , chemistry , escherichia coli , biochemistry , gene , medicine , pathology
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 initiate 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.