Functional role of the type 1 pilus rod structure in mediating host-pathogen interactions
Abstract
Uropathogenic E. coli (UPEC), which cause urinary tract infections (UTI), utilize type 1 pili, a chaperone usher pathway (CUP) pilus, to cause UTI and colonize the gut. The pilus rod, comprised of repeating FimA subunits, provides a structural scaffold for displaying the tip adhesin, FimH. We solved the 4.2 Å resolution structure of the type 1 pilus rod using cryo-electron microscopy. Residues forming the interactive surfaces that determine the mechanical properties of the rod were maintained by selection based on a global alignment of fimA sequences. We identified mutations that did not alter pilus production in vitro but reduced the force required to unwind the rod. UPEC expressing these mutant pili were significantly attenuated in bladder infection and intestinal colonization in mice. This study elucidates an unappreciated functional role for the molecular spring-like property of type 1 pilus rods in host-pathogen interactions and carries important implications for other pilus-mediated diseases.
Data availability
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Bacteria Genome sequencing and assemblyPublicly available at the NCBI BioProject Database (accession PRJNA269984).
Article and author information
Author details
Funding
National Institutes of Health (GM122510)
- Edward H Egelman
Washington University School of Medicine (Monsanto Excellence Fund Graduate Fellowship)
- Henry Louis Schreiber
National Institutes of Health (AI048689)
- Scott Hultgren
National Institutes of Health (DK064540)
- Scott Hultgren
National Institutes of Health (1F31DK107057)
- Caitlin N Spaulding
National Institutes of Health (DK101171-02)
- Matt S Conover
Svenska Forskningsrådet Formas (621-2013-5379)
- Magnus Andersson
Agence Nationale de la Recherche (ANR-14-CE09-0004)
- Olivera Francetic
Paris Pasteur University (Graduate Research Fellowship)
- Areli Luna-Rico
Washington University School of Medicine (Lucille P. Markey Pathway for Pathobiology)
- Henry Louis Schreiber
The funders had no role in study design, data collection and interpretation, or the decision to submit the work for publication.
Reviewing Editor
- Michael S Gilmore, Harvard Medical School, United States
Ethics
Animal experimentation: The Washington University Animal Studies Committee approved all procedures used for the mouse experiments described in the present study (Protocol Application Number 20150226). Overall care of the animals was consistent with The Guide for the Care and Use of Laboratory Animals from the National Research Council and the USDA Animal Care Resource Guide. Every effort was made to minimize suffering.
Version history
- Received: August 31, 2017
- Accepted: January 12, 2018
- Accepted Manuscript published: January 18, 2018 (version 1)
- Version of Record published: February 5, 2018 (version 2)
Copyright
© 2018, Spaulding et al.
This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.
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The dimeric two-pore OSCA/TMEM63 family has recently been identified as mechanically activated ion channels. Previously, based on the unique features of the structure of OSCA1.2, we postulated the potential involvement of several structural elements in sensing membrane tension (Jojoa-Cruz et al., 2018). Interestingly, while OSCA1, 2, and 3 clades are activated by membrane stretch in cell-attached patches (i.e. they are stretch-activated channels), they differ in their ability to transduce membrane deformation induced by a blunt probe (poking). Here, in an effort to understand the domains contributing to mechanical signal transduction, we used cryo-electron microscopy to solve the structure of Arabidopsis thaliana (At) OSCA3.1, which, unlike AtOSCA1.2, only produced stretch- but not poke-activated currents in our initial characterization (Murthy et al., 2018). Mutagenesis and electrophysiological assessment of conserved and divergent putative mechanosensitive features of OSCA1.2 reveal a selective disruption of the macroscopic currents elicited by poking without considerable effects on stretch-activated currents (SAC). Our results support the involvement of the amphipathic helix and lipid-interacting residues in the membrane fenestration in the response to poking. Our findings position these two structural elements as potential sources of functional diversity within the family.
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