4lp8
A Novel Open-State Crystal Structure of the Prokaryotic Inward Rectifier KirBac3.1
Structural highlights
FunctionIRK10_MAGMG Inward rectifier potassium channel that mediates potassium uptake into the cell. Inward rectifier potassium channels are characterized by a greater tendency to allow potassium to flow into the cell rather than out of it. The inward rectification may be achieved by the blockage of outward current by cytoplasmic divalent metal ions and polyamines. Complements an E.coli mutant that is defective in K(+) uptake.[1] [2] [3] Publication Abstract from PubMedKirBac channels are prokaryotic homologs of mammalian inwardly rectifying channels (Kir) 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 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 where 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. Control of KirBac3.1 potassium channel gating at the interface between cytoplasmic domains.,Zubcevic L, Bavro VN, Muniz JR, Schmidt MR, Wang S, De Zorzi R, Venien-Bryan C, Sansom MS, Nichols CG, Tucker SJ J Biol Chem. 2013 Nov 20. PMID:24257749[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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