Real time dynamics of Gating-Related conformational changes in CorA

Elife. 2019 Nov 27:8:e47322. doi: 10.7554/eLife.47322.

Abstract

CorA, a divalent-selective channel in the metal ion transport superfamily, is the major Mg2+-influx pathway in prokaryotes. CorA structures in closed (Mg2+-bound), and open (Mg2+-free) states, together with functional data showed that Mg2+-influx inhibits further Mg2+-uptake completing a regulatory feedback loop. While the closed state structure is a symmetric pentamer, the open state displayed unexpected asymmetric architectures. Using high-speed atomic force microscopy (HS-AFM), we explored the Mg2+-dependent gating transition of single CorA channels: HS-AFM movies during Mg2+-depletion experiments revealed the channel's transition from a stable Mg2+-bound state over a highly mobile and dynamic state with fluctuating subunits to asymmetric structures with varying degree of protrusion heights from the membrane. Our data shows that at Mg2+-concentration below Kd, CorA adopts a dynamic (putatively open) state of multiple conformations that imply structural rearrangements through hinge-bending in TM1. We discuss how these structural dynamics define the functional behavior of this ligand-dependent channel.

Keywords: AFM; CorA; T. maritima; ion channels; membrane transport; molecular biophysics; single molecule; structural biology.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Animals
  • Bacterial Proteins / chemistry
  • Bacterial Proteins / genetics
  • Bacterial Proteins / metabolism*
  • Cation Transport Proteins / chemistry
  • Cation Transport Proteins / genetics
  • Cation Transport Proteins / metabolism*
  • Crystallography, X-Ray
  • Female
  • Ion Channel Gating / genetics
  • Ion Channel Gating / physiology*
  • Ion Transport
  • Magnesium / metabolism
  • Microscopy, Atomic Force
  • Molecular Dynamics Simulation*
  • Oocytes / metabolism
  • Oocytes / physiology
  • Protein Conformation*
  • Thermotoga maritima / genetics
  • Thermotoga maritima / metabolism*
  • Xenopus laevis

Substances

  • Bacterial Proteins
  • Cation Transport Proteins
  • Magnesium