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Nat Microbiol. 2018 Dec;3(12):1362-1368. doi: 10.1038/s41564-018-0255-y. Epub 2018 Oct 1.

Structural basis for usher activation and intramolecular subunit transfer in P pilus biogenesis in Escherichia coli.

Author information

1
Department of Molecular Microbiology, Washington University in St Louis, St Louis, MO, USA.
2
Center for Women's Infectious Disease Research, Washington University in St Louis, St Louis, MO, USA.
3
Department of Cell Biology and Physiology, Washington University in St Louis, St Louis, MO, USA.
4
Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA.
5
Department of Chemistry, Umeå University, Umeå, Sweden.
6
Umeå Center for Microbial Research, Umeå University, Umeå, Sweden.
7
Department of Cell Biology and Physiology, Washington University in St Louis, St Louis, MO, USA. yuanp@wustl.edu.
8
Center for the Investigation of Membrane Excitability Diseases, Washington University in St Louis, St Louis, MO, USA. yuanp@wustl.edu.
9
Department of Molecular Microbiology, Washington University in St Louis, St Louis, MO, USA. Hultgren@wustl.edu.
10
Center for Women's Infectious Disease Research, Washington University in St Louis, St Louis, MO, USA. Hultgren@wustl.edu.

Abstract

Chaperone-usher pathway pili are extracellular proteinaceous fibres ubiquitously found on Gram-negative bacteria, and mediate host-pathogen interactions and biofilm formation critical in pathogenesis in numerous human diseases1. During pilus assembly, an outer membrane macromolecular machine called the usher catalyses pilus biogenesis from the individual subunits that are delivered as chaperone-subunit complexes in the periplasm. The usher orchestrates pilus assembly using all five functional domains: a 24-stranded transmembrane β-barrel translocation domain, a β-sandwich plug domain, an amino-terminal periplasmic domain and two carboxy-terminal periplasmic domains (CTD1 and CTD2)2-6. Despite extensive structural and functional characterization, the mechanism by which the usher is activated to initiate pilus biogenesis is unknown. Here, we present the crystal structure of the full-length PapC usher from Escherichia coli in complex with its cognate PapDG chaperone-subunit complex in a pre-activation state, elucidating molecular details of how the usher is specifically engaged by allosteric interactions with its substrate preceding activation and how the usher facilitates the transfer of subunits from the amino-terminal periplasmic domain to the CTDs during pilus assembly. This work elucidates the intricate workings of a molecular machine that catalyses chaperone-usher pathway pilus assembly and opens the door for the development of potent inhibitors to block pilus biogenesis.

PMID:
30275511
PMCID:
PMC6258349
DOI:
10.1038/s41564-018-0255-y
[Indexed for MEDLINE]
Free PMC Article

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