Dynamic interplay of membrane‐proximal POTRA domain and conserved loop L6 in Omp85 transporter FhaC. Issue 3 (14th August 2015)

• Record Type: Journal Article
• Authors: Guérin, Jeremy; Saint, Nathalie; Baud, Catherine; Meli, Albano C.; Etienne, Emilien; Locht, Camille; Vezin, Hervé; Jacob‐Dubuisson, Françoise
• Is Part Of: Molecular microbiology. Volume 98:Issue 3(2015)
• Page Start: 490
• Page End: 501
• Publication Date: 2015-08-14
• Subjects: Molecular microbiology -- Periodicals; 572.829
• DOI: 10.1111/mmi.13137
• Languages: English
• ISSNs: 0950-382X

Abstract

<abstract abstract-type="main"> <title>Summary</title> <p>Omp85 transporters mediate protein insertion into, or translocation across, membranes. They have a conserved architecture, with POTRA domains that interact with substrate proteins, a 16‐stranded transmembrane β barrel, and an extracellular loop, L6, folded back in the barrel pore. Here using electrophysiology, <italic>in vivo</italic> biochemical approaches and electron paramagnetic resonance, we show that the L6 loop of the Omp85 transporter FhaC changes conformation and modulates channel opening. Those conformational changes involve breaking the conserved interaction between the tip of L6 and the inner β‐barrel wall. The membrane‐proximal POTRA domain also exchanges between several conformations, and the binding of FHA displaces this equilibrium. We further demonstrate a dynamic, physical communication between the POTRA domains and L6, which must take place <italic>via</italic> the β barrel. Our findings thus link all three essential components of Omp85 transporters and indicate that they operate in a concerted fashion in the transport cycle.</p> </abstract>