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KirBac channels are prokaryotic homologs of mammalian inwardly rectifying potassium (Kir) channels, and recent structures of KirBac3.1 have provided important insights into the structural basis of gating in Kir channels. In this study, we demonstrate that KirBac3.1 channel activity is strongly pH-dependent, and we used x-ray crystallography to determine the structural changes that arise from an activatory mutation (S205L) located in the cytoplasmic domain (CTD). This mutation stabilizes a novel energetically favorable open conformation in which changes at the intersubunit interface in the CTD also alter the electrostatic potential of the inner cytoplasmic cavity. These results provide a structural explanation for the activatory effect of this mutation and provide a greater insight into the role of the CTD in Kir channel gating.

Original publication

DOI

10.1074/jbc.M113.501833

Type

Journal article

Journal

J Biol Chem

Publication Date

03/01/2014

Volume

289

Pages

143 - 151

Keywords

Channel Gating, Crystal Structure, Ion Channels, Kir Channel, KirBac, Membrane Proteins, Molecular Dynamics, Potassium Channels, Amino Acid Substitution, Bacterial Proteins, Ion Channel Gating, Magnetospirillum, Mutation, Missense, Potassium Channels, Inwardly Rectifying, Protein Structure, Tertiary