Dynamic interplay of membrane-proximal POTRA domain and conserved loop L6 in Omp85 transporter FhaC

作者：Guerin Jeremy; Saint Nathalie; Baud Catherine; Meli Albano C; Etienne Emilien; Locht Camille; Vezin Herve; Jacob Dubuisson Francoise

来源：Molecular Microbiology, 2015, 98(3): 490-501.

DOI：10.1111/mmi.13137

<jats:title>Summary</jats:title><jats:p>Omp85 transporters mediate protein insertion into, or translocation across, membranes. They have a conserved architecture, with <jats:styled-content style="fixed-case">POTRA</jats:styled-content> domains that interact with substrate proteins, a 16‐stranded transmembrane β barrel, and an extracellular loop, <jats:styled-content style="fixed-case">L</jats:styled-content>6, folded back in the barrel pore. Here using electrophysiology, <jats:italic>in vivo</jats:italic> biochemical approaches and electron paramagnetic resonance, we show that the <jats:styled-content style="fixed-case">L</jats:styled-content>6 loop of the <jats:styled-content style="fixed-case">O</jats:styled-content>mp85 transporter <jats:styled-content style="fixed-case">FhaC</jats:styled-content> changes conformation and modulates channel opening. Those conformational changes involve breaking the conserved interaction between the tip of <jats:styled-content style="fixed-case">L</jats:styled-content>6 and the inner β‐barrel wall. The membrane‐proximal <jats:styled-content style="fixed-case">POTRA</jats:styled-content> domain also exchanges between several conformations, and the binding of <jats:styled-content style="fixed-case">FHA</jats:styled-content> displaces this equilibrium. We further demonstrate a dynamic, physical communication between the <jats:styled-content style="fixed-case">POTRA</jats:styled-content> domains and <jats:styled-content style="fixed-case">L</jats:styled-content>6, which must take place <jats:italic>via</jats:italic> the β barrel. Our findings thus link all three essential components of <jats:styled-content style="fixed-case">O</jats:styled-content>mp85 transporters and indicate that they operate in a concerted fashion in the transport cycle.</jats:p>

• 出版日期2015-10