title: Charge substitution for a deep-pore residue reveals structural dynamics during BK channel gating.
abstract: The pore-lining amino acids of ion channel proteins reside on the interface between a polar (the pore) and a nonpolar environment (the rest of the protein). The structural dynamics of this region, which physically controls ionic flow, are essential components of channel gating. Using large-conductance, Ca(2+)-dependent K(+) (BK) channels, we devised a systematic charge-substitution method to probe conformational changes in the pore region during channel gating. We identified a deep-pore residue (314 in hSlo1) as a marker of structural dynamics. We manipulated the charge states of this residue by substituting amino acids with different valence and pKa, and by adjusting intracellular pH. We found that the charged states of the 314 residues stabilized an open state of the BK channel. With models based on known structures of related channels, we postulate a dynamic rearrangement of the deep-pore region during BK channel opening/closing, which involves a change of the degree of pore exposure for 314.
authors: Section of Neurobiology and Center for Learning and Memory, The University of Texas at Austin, Austin, TX 78712, USA.
authors: Xixi
authors: X
authors: Chen
authors: Richard W
authors: RW
authors: Aldrich
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001120:Arginine / Q000235:genetics / Q000378:metabolism; D002478:Cells, Cultured; D057809:HEK293 Cells; D006801:Humans; D006863:Hydrogen-Ion Concentration; D015640:Ion Channel Gating / Q000502:physiology*; D051036:Large-Conductance Calcium-Activated Potassium Channels / Q000737:chemistry* / Q000378:metabolism*; D008564:Membrane Potentials / Q000502:physiology; D008715:Methionine / Q000235:genetics / Q000378:metabolism; D008958:Models, Molecular; D017434:Protein Structure, Tertiary; D013329:Structure-Activity Relationship
chemical_list: D051036:Large-Conductance Calcium-Activated Potassium Channels; D001120:Arginine; D008715:Methionine