Abstract
AbstractChloride homeostasis is regulated in all cellular compartments. CLC-type channels selectively transport Cl− across biological membranes. It is proposed that side-chains of pore-lining residues determine Cl− selectivity in CLC-type channels, but their spatial orientation and contributions to selectivity are not conserved. This suggests a possible role for mainchain amides in selectivity. We use nonsense suppression to insert α-hydroxy acids at pore-lining positions in two CLC-type channels, CLC-0 and bCLC-k, thus exchanging peptide-bond amides with ester-bond oxygens which are incapable of hydrogen-bonding. Backbone substitutions functionally degrade inter-anion discrimination in a site-specific manner. The presence of a pore-occupying glutamate side chain modulates these effects. Molecular dynamics simulations show backbone amides determine ion energetics within the bCLC-k pore and how insertion of an α-hydroxy acid alters selectivity. We propose that backbone-ion interactions are determinants of Cl− specificity in CLC channels in a mechanism reminiscent of that described for K+ channels.
Funder
U.S. Department of Health & Human Services | NIH | National Institute of General Medical Sciences
U.S. Department of Health & Human Services | NIH | National Institute of Neurological Disorders and Stroke
NSF | BIO | Division of Biological Infrastructure
National Centre for Supercomputing Applications
Publisher
Springer Science and Business Media LLC
Subject
General Physics and Astronomy,General Biochemistry, Genetics and Molecular Biology,General Chemistry,Multidisciplinary
Cited by
1 articles.
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