@article{91c724b5b6744b43aa8c31b5831a85c3,
title = "A CLC-EC1 mutant reveals global conformational change and suggests a unifying mechanism for the CLC CL– /H+ transport cycle",
abstract = "Among coupled exchangers, CLCs uniquely catalyze the exchange of oppositely charged ions (Cl– for H+). Transport-cycle models to describe and explain this unusual mechanism have been proposed based on known CLC structures. While the proposed models harmonize with many experimental findings, gaps and inconsistencies in our understanding have remained. One limitation has been that global conformational change – which occurs in all conventional transporter mechanisms – has not been observed in any high-resolution structure. Here, we describe the 2.6 {\AA} structure of a CLC mutant designed to mimic the fully H+-loaded transporter. This structure reveals a global conformational change to improve accessibility for the Cl– substrate from the extracellular side and new conformations for two key glutamate residues. Together with DEER measurements, MD simulations, and functional studies, this new structure `provides evidence for a unified model of H+ /Cl– transport that reconciles existing data on all CLC-type proteins.",
keywords = "Antiporter, Crystallization, DEER spectroscopy, MD simulations, Membrane exchanger",
author = "Chavan, {Tanmay S.} and Cheng, {Ricky C.} and Tao Jiang and Mathews, {Irimpan I.} and Stein, {Richard A.} and Antoine Koehl and McHaourab, {Hassane S.} and Emad Tajkhorshid and Merritt Maduke",
note = "Funding Information: We thank Chris Miller and Martin Prieto for comments on the manuscript. We are grateful to Brian Kobilka for use of the crystallization equipment and to K. Chris Garcia for use of the MicroCal ITC instrument. This research was funded by NIH GM113195 (M.M., E.T., and H.S.M.) and P41-GM104601 (E.T.). T.S.C. was supported by an American Heart Association Fellowship 17POST33670553. This research used resources of the Advanced Photon Source, a US Department of Energy (DOE) Office of Science User Facility operated for the DOE Office of Science by Argonne National Laboratory under contract no. DE-AC02-06CH11357. The SSRL Structural Molecular Biology Program is supported by the DOE Office of Biological and Environmental Research, and by the National Institutes of Health, National Institute of General Medical Sciences (P41GM103393). We also acknowledge computing resources provided by Blue Waters at National Center for Supercomputing Applications (T.J.), and Extreme Science and Engineering Discovery Environment (grant MCA06N060 to E.T.). Publisher Copyright: {\textcopyright} 2020, eLife Sciences Publications Ltd. All rights reserved.",
year = "2020",
month = apr,
doi = "10.7554/eLife.53479",
language = "English (US)",
volume = "9",
journal = "eLife",
issn = "2050-084X",
publisher = "eLife Sciences Publications",
}