Interaction Between Permeation and Gating in a Putative Pore Domain Mutant in the Cystic Fibrosis Transmembrane Conductance Regulator
Autor: | Zhi-Ren Zhang, Stefan McDonough, Nael A. McCarty |
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Rok vydání: | 2000 |
Předmět: |
Patch-Clamp Techniques
Xenopus Mutant Biophysics Cystic Fibrosis Transmembrane Conductance Regulator Gating Permeability Membrane Potentials 03 medical and health sciences Adenosine Triphosphate 0302 clinical medicine Animals Magnesium ortho-Aminobenzoates Patch clamp Cells Cultured 030304 developmental biology Membrane potential 0303 health sciences biology Chemistry Conductance Calcium Channel Blockers Cystic fibrosis transmembrane conductance regulator Protein Structure Tertiary Transmembrane domain Biochemistry Mutagenesis Site-Directed Chloride channel biology.protein Calcium Ion Channel Gating 030217 neurology & neurosurgery Research Article |
Zdroj: | Biophysical Journal. 79(1):298-313 |
ISSN: | 0006-3495 |
DOI: | 10.1016/s0006-3495(00)76292-8 |
Popis: | The cystic fibrosis transmembrane conductance regulator (CFTR) is a chloride channel with distinctive kinetics. At the whole-cell level, CFTR currents in response to voltage steps are time independent for wild type and for the many mutants reported so far. Single channels open for periods lasting up to tens of seconds; the openings are interrupted by brief closures at hyperpolarized, but not depolarized, potentials. Here we report a serine-to-phenylalanine mutation (S1118F) in the 11th transmembrane domain that confers voltage-dependent, single-exponential current relaxations and moderate inward rectification of the macroscopic currents upon expression in Xenopus oocytes. At steady state, the S1118F-CFTR single-channel conductance rectifies, corresponding to the whole-cell rectification. In addition, the open-channel burst duration is decreased 10-fold compared with wild-type channels. S1118F-CFTR currents are blocked in a voltage-dependent manner by diphenylamine-2-carboxylate (DPC); the affinity of S1118F-CFTR for DPC is similar to that of the wild-type channel, but blockade exhibits moderately reduced voltage dependence. Selectivity of the channel to a range of anions is also affected by this mutation. Furthermore, the permeation properties change during the relaxations, which suggests that there is an interaction between gating and permeation in this mutant. The existence of a mutation that confers voltage dependence upon CFTR currents and that changes kinetics and permeation properties of the channel suggests a functional role for the 11th transmembrane domain in the pore in the wild-type channel. |
Databáze: | OpenAIRE |
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