Molecular mechanism of arachidonic acid inhibition of the CFTR chloride channel.
Arachidonic acid inhibits the activity of a number of different Cl- channels, however its molecular mechanism of action is not known. Here we show that inhibition of cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channels by arachidonic acid is weakened following mutagenesis of two positively charged pore-lining amino acids. Charge-neutralizing mutants K95Q and R303Q both increased the Kd for inhibition from approximately 3.5 microM in wild type to approximately 17 microM. At both sites, the effects of mutagenesis were dependent of the charge of the substituted side chain. We suggest that arachidonic acid interacts electrostatically with positively charged amino acid side chains in the cytoplasmic vestibule of the CFTR channel pore to block Cl- permeation.
Zhou
Jing-Jun
JJ
Department of Physiology & Biophysics, Dalhousie University, 5850 College Street, Halifax, Nova Scotia, Canada B3H 1X5.
Linsdell
Paul
P
D000818:Animals; D016718:Arachidonic Acid / Q000378:metabolism* / Q000494:pharmacology; D001120:Arginine; D002460:Cell Line; D002712:Chlorides / Q000378:metabolism; D006224:Cricetinae; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000037:antagonists & inhibitors / Q000235:genetics / Q000378:metabolism*; D004305:Dose-Response Relationship, Drug; D005973:Glutamine; D015640:Ion Channel Gating / Q000187:drug effects; D008239:Lysine; D008564:Membrane Potentials; D009154:Mutation; D018408:Patch-Clamp Techniques; D014162:Transfection
D002712:Chlorides; D005973:Glutamine; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D016718:Arachidonic Acid; D001120:Arginine; D008239:Lysine