title: A designed inhibitor of a CLC antiporter blocks function through a unique binding mode.
abstract: The lack of small-molecule inhibitors for anion-selective transporters and channels has impeded our understanding of the complex mechanisms that underlie ion passage. The ubiquitous CLC "Chloride Channel" family represents a unique target for biophysical and biochemical studies because its distinctive protein fold supports both passive chloride channels and secondary-active chloride-proton transporters. Here, we describe the synthesis and characterization of a specific small-molecule inhibitor directed against a CLC antiporter (ClC-ec1). This compound, 4,4'-octanamidostilbene-2,2'-disulfonate (OADS), inhibits ClC-ec1 with low micromolar affinity and has no specific effect on a CLC channel (ClC-1). Inhibition of ClC-ec1 occurs by binding to two distinct intracellular sites. The location of these sites and the lipid dependence of inhibition suggest potential mechanisms of action. This compound will empower research to elucidate differences between antiporter and channel mechanisms and to develop treatments for CLC-mediated disorders.
authors.affiliation: Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford University, Stanford, CA 94305, USA.
authors.forename: Andrew E
authors.initials: AE
authors.lastname: Howery
authors.forename: Shelley
authors.initials: S
authors.lastname: Elvington
authors.forename: Sherwin J
authors.initials: SJ
authors.lastname: Abraham
authors.forename: Kee-Hyun
authors.initials: KH
authors.lastname: Choi
authors.forename: Sierra
authors.initials: S
authors.lastname: Dworschak-Simpson
authors.forename: Sabrina
authors.initials: S
authors.lastname: Phillips
authors.forename: Christopher M
authors.initials: CM
authors.lastname: Ryan
authors.forename: R Lea
authors.initials: RL
authors.lastname: Sanford
authors.forename: Jonas
authors.initials: J
authors.lastname: Almqvist
authors.forename: Kevin
authors.initials: K
authors.lastname: Tran
authors.forename: Thomas A
authors.initials: TA
authors.lastname: Chew
authors.forename: Ulrich
authors.initials: U
authors.lastname: Zachariae
authors.forename: Olaf S
authors.initials: OS
authors.lastname: Andersen
authors.forename: Julian
authors.initials: J
authors.lastname: Whitelegge
authors.forename: Kimberly
authors.initials: K
authors.lastname: Matulef
authors.forename: Justin
authors.initials: J
authors.lastname: Du Bois
authors.forename: Merritt C
authors.initials: MC
authors.lastname: Maduke
mesh_terms: D017920:Antiporters / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D018118:Chloride Channels / Q000378:metabolism*; D029968:Escherichia coli Proteins / Q000037:antagonists & inhibitors / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D008051:Lipid Bilayers; D056004:Molecular Dynamics Simulation; D009154:Mutation; D013267:Stilbenes / Q000378:metabolism / Q000494:pharmacology*; D013451:Sulfonic Acids / Q000378:metabolism / Q000494:pharmacology*
chemical_list: C580876:4,4'-octanamidostilbene-2,2'-disulfonic acid; D017920:Antiporters; C086321:CLC-1 channel; C570787:CLC-ec1 protein, E coli; D018118:Chloride Channels; D029968:Escherichia coli Proteins; D008051:Lipid Bilayers; D013267:Stilbenes; D013451:Sulfonic Acids