The role of a conserved lysine in chloride- and voltage-dependent ClC-0 fast gating.
ClC-0 is a chloride channel whose gating is sensitive to voltage, chloride, and pH. In a previous publication, we showed that the K149C mutation causes a +70-mV shift in the voltage dependence of ClC-0 fast gating. In this paper we analyze the effects of a series of mutations at K149 on the voltage and chloride dependence of gating. By fitting our data to the previously proposed four-state model for ClC-0 fast gating, we show which steps in fast-gate opening are likely to be affected by these mutations. Computational analysis of mutant ClC-0 homology models show electrostatic contributions to chloride binding that may partially account for the effects of K149 on gating. The analysis of gating kinetics in combination with the available structural information suggests some of the structural changes likely to underpin fast-gate opening.
Engh
Anita M
AM
Department of Molecular and Cellular Physiology, Stanford University School of Medicine, Stanford, CA 94305, USA.
Faraldo-Gómez
José D
JD
Maduke
Merritt
M
D019943:Amino Acid Substitution / Q000502:physiology*; D000818:Animals; D001665:Binding Sites / Q000502:physiology; D018118:Chloride Channels / Q000737:chemistry / Q000378:metabolism; D002712:Chlorides / Q000737:chemistry / Q000378:metabolism; D005163:Factor Analysis, Statistical; D015640:Ion Channel Gating; D007700:Kinetics; D008239:Lysine; D008564:Membrane Potentials / Q000502:physiology; D008954:Models, Biological; D017434:Protein Structure, Tertiary / Q000502:physiology; D012044:Regression Analysis; D055672:Static Electricity; D013329:Structure-Activity Relationship; D014101:Torpedo / Q000378:metabolism
C120501:CLC-0 chloride channel protein, Torpedo californica; D018118:Chloride Channels; D002712:Chlorides; D008239:Lysine