title: Block by MOPS reveals a conformation change in the CFTR pore produced by ATP hydrolysis.
abstract: ATP hydrolysis by the cystic fibrosis transmembrane conductance regulator (CFTR) Cl- channel predicts that energy from hydrolysis might cause asymmetric transitions in the gating cycle. We found that 3-(N-morpholino)propanesulfonic acid (MOPS) blocked the open channel by binding to a site 50% of the way through the electrical field. Block by MOPS revealed two distinct states, O1 and O2, which showed a strong asymmetry during bursts of activity; the first opening in a burst was in the O1 state and the last was in the O2 state. Addition of a nonhydrolyzable nucleoside triphosphate prevented the transition to the O2 state and prolonged the O1 state. These data indicate that ATP hydrolysis by the nucleotide-binding domains drives a series of asymmetric transitions in the gating cycle. They also indicate that ATP hydrolysis changes the conformation of the pore, thereby altering MOPS binding.
authors.affiliation: Howard Hughes Medical Institute, Department of Internal Medicine, University of Iowa College of Medicine, Iowa City 52242, USA.
authors.forename: H
authors.initials: H
authors.lastname: Ishihara
authors.forename: M J
authors.initials: MJ
authors.lastname: Welsh
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism*; D000266:Adenylyl Imidodiphosphate / Q000494:pharmacology; D000818:Animals; D002460:Cell Line; D017868:Cyclic AMP-Dependent Protein Kinases / Q000378:metabolism; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry* / Q000187:drug effects / Q000502:physiology*; D005998:Glycine / Q000031:analogs & derivatives / Q000494:pharmacology; D006367:HeLa Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015640:Ion Channel Gating; D007700:Kinetics; D008564:Membrane Potentials; D051379:Mice; D008961:Models, Structural; D009025:Morpholines / Q000494:pharmacology*; D018408:Patch-Clamp Techniques; D011487:Protein Conformation / Q000187:drug effects*; D011994:Recombinant Proteins / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D014162:Transfection
chemical_list: C505032:CFTR protein, human; D009025:Morpholines; D011994:Recombinant Proteins; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000266:Adenylyl Imidodiphosphate; C008550:morpholinopropane sulfonic acid; D000255:Adenosine Triphosphate; D017868:Cyclic AMP-Dependent Protein Kinases; D005998:Glycine; C100184:tricine