title: Regulation of CNGA1 Channel Gating by Interactions with the Membrane.
abstract: Cyclic nucleotide-gated (CNG) channels are expressed in rod photoreceptors and open in response to direct binding of cyclic nucleotides. We have previously shown that potentiation of CNGA1 channels by transition metals requires a histidine in the A' helix following the S6 transmembrane segment. Here, we used transition metal ion FRET and patch clamp fluorometry with a fluorescent, noncanonical amino acid (3-(6-acetylnaphthalen-2-ylamino)-2-aminopropanoic acid (Anap)) to show that the potentiating transition metal Co(2+) binds in or near the A' helix. Adding high-affinity metal-binding sites to the membrane (stearoyl-nitrilotriacetic acid (C18-NTA)) increased potentiation for low Co(2+) concentrations, indicating that the membrane can coordinate metal ions with the A' helix. These results suggest that restraining the A' helix to the plasma membrane potentiates CNGA1 channel opening. Similar interactions between the A' helix and the plasma membrane may underlie regulation of structurally related hyperpolarization-activated cyclic nucleotide-gated (HCN) and voltage-gated potassium subfamily H (KCNH) channels by plasma membrane components.
authors.affiliation: From the Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195.
authors.forename: Teresa K
authors.initials: TK
authors.lastname: Aman
authors.affiliation: From the Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195.
authors.forename: Sharona E
authors.initials: SE
authors.lastname: Gordon
authors.affiliation: From the Department of Physiology and Biophysics, University of Washington, Seattle, Washington 98195 zagotta@uw.edu.
authors.forename: William N
authors.initials: WN
authors.lastname: Zagotta
mesh_terms: D000818:Animals; D002417:Cattle; D002462:Cell Membrane / Q000235:genetics / Q000378:metabolism*; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000235:genetics / Q000378:metabolism*; D015640:Ion Channel Gating / Q000187:drug effects / Q000502:physiology*; D009865:Oocytes / Q000378:metabolism; D011422:Propionates / Q000494:pharmacology; D017433:Protein Structure, Secondary; D014982:Xenopus laevis
chemical_list: C475741:CNGA1 protein, bovine; D054815:Cyclic Nucleotide-Gated Cation Channels; D011422:Propionates
keywords: cyclic nucleotide; electrophysiology; fluorescence resonance energy transfer (FRET); ion channel; metal ion FRET (tmFRET); patch clamp fluorometry (PCF); plasma membrane; unnatural amino acid