title: Structure of the transmembrane regions of a bacterial cyclic nucleotide-regulated channel.
abstract: The six-transmembrane helix (6 TM) tetrameric cation channels form the largest ion channel family, some members of which are voltage-gated and others are not. There are no reported channel structures to match the wealth of functional data on the non-voltage-gated members. We determined the structure of the transmembrane regions of the bacterial cyclic nucleotide-regulated channel MlotiK1, a non-voltage-gated 6 TM channel. The structure showed how the S1-S4 domain and its associated linker can serve as a clamp to constrain the gate of the pore and possibly function in concert with ligand-binding domains to regulate the opening of the pore. The structure also led us to hypothesize a new mechanism by which motions of the S6 inner helices can gate the ion conduction pathway at a position along the pore closer to the selectivity filter than the canonical helix bundle crossing.
authors.affiliation: Department of Molecular Biophysics and Biochemistry, Yale University, 260 Whitney Avenue, New Haven, CT 06520, USA.
authors.forename: Gina M
authors.initials: GM
authors.lastname: Clayton
authors.forename: Steve
authors.initials: S
authors.lastname: Altieri
authors.forename: Lise
authors.initials: L
authors.lastname: Heginbotham
authors.forename: Vinzenz M
authors.initials: VM
authors.lastname: Unger
authors.forename: João H
authors.initials: JH
authors.lastname: Morais-Cabral
mesh_terms: D020561:Alphaproteobacteria / Q000378:metabolism*; D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D018360:Crystallography, X-Ray; D054815:Cyclic Nucleotide-Gated Cation Channels / Q000737:chemistry* / Q000235:genetics; D008969:Molecular Sequence Data; D015221:Potassium Channels / Q000737:chemistry* / Q000235:genetics; D011487:Protein Conformation
chemical_list: D001426:Bacterial Proteins; D054815:Cyclic Nucleotide-Gated Cation Channels; D015221:Potassium Channels