2jty | pdb_00002jty
Self-complemented variant of FimA, the main subunit of type 1 pilus
Structural highlights
FunctionFIMA1_ECOLI Fimbriae (also called pili), polar filaments radiating from the surface of the bacterium to a length of 0.5-1.5 micrometers and numbering 100-300 per cell, enable bacteria to colonize the epithelium of specific host organs. Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedFilamentous type 1 pili are responsible for attachment of uropathogenic Escherichia coli strains to host cells. They consist of a linear tip fibrillum and a helical rod formed by up to 3000 copies of the main structural pilus subunit FimA. The subunits in the pilus interact via donor strand complementation, where the incomplete, immunoglobulin-like fold of each subunit is complemented by an N-terminal donor strand of the subsequent subunit. Here, we show that folding of FimA occurs at an extremely slow rate (half-life: 1.6 h) and is catalyzed more than 400-fold by the pilus chaperone FimC. Moreover, FimA is capable of intramolecular self-complementation via its own donor strand, as evidenced by the loss of folding competence upon donor strand deletion. Folded FimA is an assembly-incompetent monomer of low thermodynamic stability (-10.1 kJ mol(-1)) that can be rescued for pilus assembly at 37 degrees C because FimC selectively pulls the fraction of unfolded FimA molecules from the FimA folding equilibrium and allows FimA refolding on its surface. Elongation of FimA at the C-terminus by its own donor strand generated a self-complemented variant (FimAa) with alternative folding possibilities that spontaneously adopts the more stable conformation (-85.0 kJ mol(-1)) in which the C-terminal donor strand is inserted in the opposite orientation relative to that in FimA. The solved NMR structure of FimAa revealed extensive beta-sheet hydrogen bonding between the FimA pilin domain and the C-terminal donor strand and provides the basis for reconstruction of an atomic model of the pilus rod. Structure, Folding and Stability of FimA, the Main Structural Subunit of Type 1 Pili from Uropathogenic Escherichia coli Strains.,Puorger C, Vetsch M, Wider G, Glockshuber R J Mol Biol. 2011 Jul 27. PMID:21816158[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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