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Crystal structure of the FimD usher bound to its cognate FimC:FimH substrate
Journal article   Peer reviewed

Crystal structure of the FimD usher bound to its cognate FimC:FimH substrate

Gilles Phan, Han Remaut, Tao Wang, William J Allen, Katharina F Pirker, Andrey Lebedev, Nadine S Henderson, Sebastian Geibel, Ender Volkan, Jun Yan, …
Nature (London), Vol.474(7349), pp.49-53
06/02/2011
DOI: 10.1038/nature10109
PMCID: PMC3162478
PMID: 21637253

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Abstract

Type 1 pili are the archetypal representative of a widespread class of adhesive multisubunit fibres in Gram-negative bacteria. During pilus assembly, subunits dock as chaperone-bound complexes to an usher, which catalyzes their polymerization and mediates pilus translocation across the outer membrane. We report the crystal structure of the full-length FimD usher bound to the FimC:FimH chaperone:adhesin complex and that of the unbound form of the FimD translocation domain. The FimD:FimC:FimH structure shows FimH inserted inside the FimD 24-stranded β-barrel translocation channel. FimC:FimH is held in place through interactions with the two C-terminal periplasmic domains of FimD, a binding mode confirmed in solution by electron paramagnetic resonance spectroscopy. To accommodate FimH, the usher plug domain is displaced from the barrel lumen to the periplasm, concomitant with a dramatic conformational change in the β-barrel. The N-terminal domain of FimD is observed in an ideal position to catalyse incorporation of a newly recruited chaperone:subunit complex. The FimD:FimC:FimH structure provides unique insights into the pilus subunit incorporation cycle, and captures the first view of a protein transporter in the act of secreting its cognate substrate.

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