title: A stable ATP binding to the nucleotide binding domain is important for reliable gating cycle in an ABC transporter CFTR.
abstract: Cystic fibrosis transmembrane conductance regulator (CFTR) anion channel, a member of ABC transporter superfamily, gates following ATP-dependent conformational changes of the nucleotide binding domains (NBD). Reflecting the hundreds of milliseconds duration of the channel open state corresponding to the dimerization of two NBDs, macroscopic WT-CFTR currents usually showed a fast, single exponential relaxation upon removal of cytoplasmic ATP. Mutations of tyrosine1219, a residue critical for ATP binding in second NBD (NBD2), induced a significant slow phase in the current relaxation, suggesting that weakening ATP binding affinity at NBD2 increases the probability of the stable open state. The slow phase was effectively diminished by a higher affinity ATP analogue. These data suggest that a stable binding of ATP to NBD2 is required for normal CFTR gating cycle, andthat the instability of ATP binding frequently halts the gating cycle in the open state presumably through a failure of ATP hydrolysis at NBD2.
authors.affiliation: John M. Dalton Cardiovascular Research Center, University of Missouri-Columbia, Columbia, MO 65211, USA.
authors.forename: Hiroyasu
authors.initials: H
authors.lastname: Shimizu
authors.forename: Ying-Chun
authors.initials: YC
authors.lastname: Yu
authors.forename: Koichi
authors.initials: K
authors.lastname: Kono
authors.forename: Takahiro
authors.initials: T
authors.lastname: Kubota
authors.forename: Masato
authors.initials: M
authors.lastname: Yasui
authors.forename: Min
authors.initials: M
authors.lastname: Li
authors.forename: Tzyh-Chang
authors.initials: TC
authors.lastname: Hwang
authors.forename: Yoshiro
authors.initials: Y
authors.lastname: Sohma
mesh_terms: D018528:ATP-Binding Cassette Transporters / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D000255:Adenosine Triphosphate / Q000737:chemistry / Q000378:metabolism*; D000818:Animals; D001665:Binding Sites / Q000235:genetics; D016466:CHO Cells; D006224:Cricetinae; D003412:Cricetulus; D019005:Cystic Fibrosis Transmembrane Conductance Regulator / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D005260:Female; D015640:Ion Channel Gating; D009154:Mutation; D011485:Protein Binding; D055503:Protein Multimerization
chemical_list: D018528:ATP-Binding Cassette Transporters; D019005:Cystic Fibrosis Transmembrane Conductance Regulator; D000255:Adenosine Triphosphate