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XB-ART-55247
Proc Natl Acad Sci U S A 2018 May 22;11521:E4900-E4909. doi: 10.1073/pnas.1720584115.
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A selective class of inhibitors for the CLC-Ka chloride ion channel.

Koster AK , Wood CAP , Thomas-Tran R , Chavan TS , Almqvist J , Choi KH , Du Bois J , Maduke M .


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CLC proteins are a ubiquitously expressed family of chloride-selective ion channels and transporters. A dearth of pharmacological tools for modulating CLC gating and ion conduction limits investigations aimed at understanding CLC structure/function and physiology. Herein, we describe the design, synthesis, and evaluation of a collection of N-arylated benzimidazole derivatives (BIMs), one of which (BIM1) shows unparalleled (>20-fold) selectivity for CLC-Ka over CLC-Kb, the two most closely related human CLC homologs. Computational docking to a CLC-Ka homology model has identified a BIM1 binding site on the extracellular face of the protein near the chloride permeation pathway in a region previously identified as a binding site for other less selective inhibitors. Results from site-directed mutagenesis experiments are consistent with predictions of this docking model. The residue at position 68 is 1 of only ∼20 extracellular residues that differ between CLC-Ka and CLC-Kb. Mutation of this residue in CLC-Ka and CLC-Kb (N68D and D68N, respectively) reverses the preference of BIM1 for CLC-Ka over CLC-Kb, thus showing the critical role of residue 68 in establishing BIM1 selectivity. Molecular docking studies together with results from structure-activity relationship studies with 19 BIM derivatives give insight into the increased selectivity of BIM1 compared with other inhibitors and identify strategies for further developing this class of compounds.

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Species referenced: Xenopus laevis
Genes referenced: bcl2l11

References [+] :
Abeyrathne, Biochemical and biophysical approaches to study the structure and function of the chloride channel (ClC) family of proteins. 2016, Pubmed