Abstract
Uropathogenic Escherichia coli attach to tissues using pili type 1. Each pilus is composed by thousands of coiled FimA domains followed by the domains of the tip fibrillum, FimF-FimG-FimH. The domains are linked by non-covalent β-strands that must resist mechanical forces during attachment. Here, we use single-molecule force spectroscopy to measure the mechanical contribution of each domain to the stability of the pilus and monitor the oxidative folding mechanism of a single Fim domain assisted by periplasmic FimC and the oxidoreductase DsbA. We demonstrate that pilus domains bear high mechanical stability following a hierarchy by which domains close to the tip are weaker than those close to or at the pilus rod. During folding, this remarkable stability is achieved by the intervention of DsbA that not only forms strategic disulfide bonds but also serves as a chaperone assisting the folding of the domains.
Highlights
Uropathogenic Escherichia coli attach to tissues using pili type 1
In the case of uropathogenic Escherichia coli (UPEC), one of the most common and recurrent infections[1], bacteria use long appendages called pili type 12,3 to attach to cells of the bladder epithelium
Here we report a mechanical characterization of the type 1 pilus domains complemented with their cognate β-strands
Summary
Uropathogenic Escherichia coli attach to tissues using pili type 1. We demonstrate that pilus domains bear high mechanical stability following a hierarchy by which domains close to the tip are weaker than those close to or at the pilus rod During folding, this remarkable stability is achieved by the intervention of DsbA that forms strategic disulfide bonds and serves as a chaperone assisting the folding of the domains. We have complemented the AFM measurements with Steered Molecular Dynamics (SMD) simulations, which give an atomic-level view of the unfolding process This extraordinary resistance is achieved by a folding process of pilus subunits assisted by DsbA and FimC. We provide a detailed nanomechanical description of the pilus chain in terms of mechanical design and subunit maturation This description complements previous information to provide a qualitative and quantitative overview of how bacteria generate pili for strong attachment to tissues in order to initiate infection
Sign-in/Register to view highlights & summary 
Published Version (
Free)
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a call