Conformational dynamics of protein transporter FhaC: large‐scale motions of plug helix. Issue 6 (9th April 2014)

• Record Type: Journal Article
• Authors: Guérin, Jérémy; Baud, Catherine; Touati, Nadia; Saint, Nathalie; Willery, Eve; Locht, Camille; Vezin, Hervé; Jacob‐Dubuisson, Françoise
• Is Part Of: Molecular microbiology. Volume 92:Issue 6(2014)
• Page Start: 1164
• Page End: 1176
• Publication Date: 2014-04-09
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.12585
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>FhaC is an integral outer membrane protein of the whooping cough agent <italic>B</italic><italic>ordetella pertussis</italic> that mediates the transport to the cell surface of a major virulence factor, the filamentous haemagglutinin adhesin FHA. The FHA/FhaC pair is a prototypic TpsA/TpsB system of the widespread 'Two‐Partner Secretion' pathway, dedicated to the transport of long extracellular proteins in various pathogenic and environmental Gram‐negative bacteria. FhaC belongs to the ubiquitous Omp85 superfamily of protein transporters. The X‐ray structure of FhaC shows that the transmembrane β‐barrel channel hypothesized to serve as the FHA‐conducting pore is obstructed by two structural elements conserved among TpsB transporters, an N‐terminal α helix and an extracellular loop. Here, we provide evidence for conformational dynamics of FhaC related to the secretion mechanism. Using paramagnetic electron resonance, electrophysiology and <italic>in vivo</italic> approaches, we showed that FhaC exchanges between open and closed conformations. The interaction with its secretory partner FHA alters this distribution of conformations. The open conformation of FhaC implies a large displacement from the channel of the N‐terminal 'plug' helix, which remains in the periplasm during FHA secretion. The membrane environment favours the dynamics of the TpsB transporter.</p> </abstract>