Structure and insights into the function of a Ca(2+)-activated Cl(-) channel.Kane Dickson, V., Pedi, L., Long, S.B.
(2014) Nature 516: 213-218
- PubMed: 25337878
- DOI: https://doi.org/10.1038/nature13913
- Primary Citation of Related Structures:
- PubMed Abstract:
Bestrophin calcium-activated chloride channels (CaCCs) regulate the flow of chloride and other monovalent anions across cellular membranes in response to intracellular calcium (Ca(2+)) levels. Mutations in bestrophin 1 (BEST1) cause certain eye diseases. Here we present X-ray structures of chicken BEST1-Fab complexes, at 2.85 Å resolution, with permeant anions and Ca(2+). Representing, to our knowledge, the first structure of a CaCC, the eukaryotic BEST1 channel, which recapitulates CaCC function in liposomes, is formed from a pentameric assembly of subunits. Ca(2+) binds to the channel's large cytosolic region. A single ion pore, approximately 95 Å in length, is located along the central axis and contains at least 15 binding sites for anions. A hydrophobic neck within the pore probably forms the gate. Phenylalanine residues within it may coordinate permeating anions via anion-π interactions. Conformational changes observed near the 'Ca(2+) clasp' hint at the mechanism of Ca(2+)-dependent gating. Disease-causing mutations are prevalent within the gating apparatus.
Structural Biology Program, Memorial Sloan Kettering Cancer Center, 1275 York Avenue, New York, New York 10065, USA.