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Functional Complementation and Genetic Deletion Studies of KirBac Channels: Activity Mutations Hightlight Gating-Sensitive Domains

Lookup NU author(s): Dr Stephen Tottey, Professor Nigel Robinson


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The superfamily of prokaryotic inwardly rectifying (KirBac) potassium channels is homologous to mammalian Kir channels. However, relatively little is known about their regulation or about their physiological role in vivo. In this study, we have used random mutagenesis and genetic complementation in K+-auxotrophic Escherichia coli and Saccharomyces cerevisiae to identify activatory mutations in a range of different KirBac channels. We also show that the KirBac6.1 gene (slr5078) is necessary for normal growth of the cyanobacterium Synechocystis PCC6803. Functional analysis and molecular dynamics simulations of selected activatory mutations identified regions within the slide helix, transmembrane helices, and C terminus that function as important regulators of KirBac channel activity, as well as a region close to the selectivity filter of KirBac3.1 that may have an effect on gating. In particular, the mutations identified in TM2 favor a model of KirBac channel gating in which opening of the pore at the helix-bundle crossing plays a far more important role than has recently been proposed.

Publication metadata

Author(s): Paynter JJ, Andres-Enguix I, Fowler PW, Tottey S, Cheng W, Enkvetchakul D, Bavro VN, Kusakabe Y, Sansom MSP, Robinson NJ, Nichols CG, Tucker SJ

Publication type: Article

Publication status: Published

Journal: Journal of Biological Chemistry

Year: 2010

Volume: 285

Issue: 52

Pages: 40754-40761

Print publication date: 24/12/2010

ISSN (print): 0021-9258

ISSN (electronic): 1083-351X

Publisher: American Society for Biochemistry and Molecular Biology, Inc.


DOI: 10.1074/jbc.M110.175687


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Funder referenceFunder name
British Heart Foundation
Wellcome Trust
BB/H006052/1Biotechnology and Biological Sciences Research Council
DK069424National Institutes of Health
HL54171National Institutes of Health