Evaluating inositol phospholipid interactions with inward rectifier potassium channels and characterising their role in disease

Tanadet Pipatpolkai; Robin A Corey; Peter Proks; Frances M Ashcroft; Phillip J Stansfeld

doi:10.1038/s42004-020-00391-0

Evaluating inositol phospholipid interactions with inward rectifier potassium channels and characterising their role in disease

Commun Chem. 2020 Oct 30;3(1):147. doi: 10.1038/s42004-020-00391-0.

Authors

Tanadet Pipatpolkai^{1

2

3}, Robin A Corey², Peter Proks^{1

3}, Frances M Ashcroft^{4

5}, Phillip J Stansfeld^{6

7

8}

Affiliations

¹ Department of Physiology Anatomy and Genetics, Parks Road, Oxford, OX1 3PT, UK.
² Department of Biochemistry, South Parks Road, Oxford, OX1 3QU, UK.
³ OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford, OX1 3PT, UK.
⁴ Department of Physiology Anatomy and Genetics, Parks Road, Oxford, OX1 3PT, UK. frances.ashcroft@dpag.ox.ac.uk.
⁵ OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford, OX1 3PT, UK. frances.ashcroft@dpag.ox.ac.uk.
⁶ Department of Biochemistry, South Parks Road, Oxford, OX1 3QU, UK. phillip.stansfeld@warwick.ac.uk.
⁷ OXION Initiative in Ion Channels and Disease, University of Oxford, Oxford, OX1 3PT, UK. phillip.stansfeld@warwick.ac.uk.
⁸ Department of Chemistry, School of Life Sciences, University of Warwick, Coventry, CV4 7AL, UK. phillip.stansfeld@warwick.ac.uk.

Abstract

Membrane proteins are frequently modulated by specific protein-lipid interactions. The activation of human inward rectifying potassium (hKir) channels by phosphoinositides (PI) has been well characterised. Here, we apply a coarse-grained molecular dynamics free-energy perturbation (CG-FEP) protocol to capture the energetics of binding of PI lipids to hKir channels. By using either a single- or multi-step approach, we establish a consistent value for the binding of PIP₂ to hKir channels, relative to the binding of the bulk phosphatidylcholine phospholipid. Furthermore, by perturbing amino acid side chains on hKir6.2, we show that the neonatal diabetes mutation E179K increases PIP₂ affinity, while the congenital hyperinsulinism mutation K67N results in a reduced affinity. We show good agreement with electrophysiological data where E179K exhibits a reduction in neomycin sensitivity, implying that PIP₂ binds more tightly E179K channels. This illustrates the application of CG-FEP to compare affinities between lipid species, and for annotating amino acid residues.

Abstract

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