4Y2L
Structure of CFA/I pili major subunit CfaB trimer
Summary for 4Y2L
Entry DOI | 10.2210/pdb4y2l/pdb |
Related | 4Y2N 4Y2O |
Descriptor | CFA/I fimbrial subunit B, ISOPROPYL ALCOHOL, CALCIUM ION, ... (4 entities in total) |
Functional Keywords | enterotoxigenic escherichia coli, periplasmic chaperone, major pilin, self-assembly, fimbriae, structural protein |
Biological source | Escherichia coli O78:H11 (strain H10407 / ETEC) |
Total number of polymer chains | 6 |
Total formula weight | 95990.03 |
Authors | |
Primary citation | Bao, R.,Liu, Y.,Savarino, S.J.,Xia, D. Off-pathway assembly of fimbria subunits is prevented by chaperone CfaA of CFA/I fimbriae from enterotoxigenic E. coli. Mol. Microbiol., 102:975-991, 2016 Cited by PubMed Abstract: The assembly of the class 5 colonization factor antigen I (CFA/I) fimbriae of enterotoxigenic E. coli was proposed to proceed via the alternate chaperone-usher pathway. Here, we show that in the absence of the chaperone CfaA, CfaB, the major pilin subunit of CFA/I fimbriae, is able to spontaneously refold and polymerize into cyclic trimers. CfaA kinetically traps CfaB to form a metastable complex that can be stabilized by mutations. Crystal structure of the stabilized complex reveals distinctive interactions provided by CfaA to trap CfaB in an assembly competent state through donor-strand complementation (DSC) and cleft-mediated anchorage. Mutagenesis indicated that DSC controls the stability of the chaperone-subunit complex and the cleft-mediated anchorage of the subunit C-terminus additionally assist in subunit refolding. Surprisingly, over-stabilization of the chaperone-subunit complex led to delayed fimbria assembly, whereas destabilizing the complex resulted in no fimbriation. Thus, CfaA acts predominantly as a kinetic trap by stabilizing subunit to avoid its off-pathway self-polymerization that results in energetically favorable trimers and could serve as a driving force for CFA/I pilus assembly, representing an energetic landscape unique to class 5 fimbria assembly. PubMed: 27627030DOI: 10.1111/mmi.13530 PDB entries with the same primary citation |
Experimental method | X-RAY DIFFRACTION (1.746 Å) |
Structure validation
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