title: Modular Design of the Selectivity Filter Pore Loop in a Novel Family of Prokaryotic 'Inward Rectifier' (NirBac) channels.
abstract: Potassium channels exhibit a modular design with distinct structural and functional domains; in particular, a highly conserved pore-loop sequence that determines their ionic selectivity. We now report the functional characterisation of a novel group of functionally non-selective members of the prokaryotic 'inward rectifier' subfamily of K(+) channels. These channels share all the key structural domains of eukaryotic and prokaryotic Kir/KirBac channels, but instead possess unique pore-loop selectivity filter sequences unrelated to any other known ionic selectivity filter. The strikingly unusual architecture of these 'NirBac' channels defines a new family of functionally non-selective ion channels, and also provides important insights into the modular design of ion channels, as well as the evolution of ionic selectivity within this superfamily of tetrameric cation channels.
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom.
authors.forename: Lejla
authors.initials: L
authors.lastname: Zubcevic
authors.affiliation: Washington University St. Louis, School Of Medicine, Centre for the Investigation of Membrane Excitability Diseases (CIMED), St. Louis, MO, USA.
authors.forename: Shizhen
authors.initials: S
authors.lastname: Wang
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom.
authors.forename: Vassiliy N
authors.initials: VN
authors.lastname: Bavro
authors.affiliation: Washington University St. Louis, School Of Medicine, Centre for the Investigation of Membrane Excitability Diseases (CIMED), St. Louis, MO, USA.
authors.forename: Sun-Joo
authors.initials: SJ
authors.lastname: Lee
authors.affiliation: Washington University St. Louis, School Of Medicine, Centre for the Investigation of Membrane Excitability Diseases (CIMED), St. Louis, MO, USA.
authors.forename: Colin G
authors.initials: CG
authors.lastname: Nichols
authors.affiliation: Clarendon Laboratory, Department of Physics, University of Oxford, Oxford, United Kingdom.|OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford, United Kingdom.
authors.forename: Stephen J
authors.initials: SJ
authors.lastname: Tucker
mesh_terms: D000595:Amino Acid Sequence; D001426:Bacterial Proteins / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D019143:Evolution, Molecular; D017136:Ion Transport; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009231:Myxococcales / Q000378:metabolism; D010802:Phylogeny; D024661:Potassium Channels, Inwardly Rectifying / Q000145:classification / Q000235:genetics / Q000378:metabolism*; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000096:biosynthesis / Q000737:chemistry / Q000302:isolation & purification
chemical_list: D001426:Bacterial Proteins; D024661:Potassium Channels, Inwardly Rectifying; D011994:Recombinant Proteins