The University of Southampton
University of Southampton Institutional Repository

The interfacial lipid binding site on the potassium channel KcsA is specific for anionic phospholipids

The interfacial lipid binding site on the potassium channel KcsA is specific for anionic phospholipids
The interfacial lipid binding site on the potassium channel KcsA is specific for anionic phospholipids
Lipid binding to the potassium channel KcsA from Streptomyces lividans has been studied using quenching of the fluorescence of Trp residues by brominated phospholipids. It is shown that binding of phospholipids to nonannular lipid binding sites on KcsA, located one each at the four protein-protein interfaces in the tetrameric structure, is specific for anionic phospholipids, zwitterionic phosphatidylcholine being unable to bind at the sites. The binding constant for phosphatidylglycerol of 3.0 ± 0.7 mol fraction–1 means that in a membrane containing ~20 mol% phosphatidylglycerol, as in the Escherichia coli inner membrane, the nonannular sites will be ~37% occupied by phosphatidylglycerol. The binding constant for phosphatidic acid is similar to that for phosphatidylglycerol but binding constants for phosphatidylserine and cardiolipin are about double those for phosphatidylglycerol. Binding to annular sites around the circumference of the KcsA tetramer are different on the extracellular and intracellular faces of the membrane. On the extracellular face of the membrane the binding constants for anionic lipids are similar to those for phosphatidylcholine, the lack of specificity being consistent with the lack of any marked clusters of charged residues on KcsA close to the membrane on the extracellular side. In contrast, binding to annular sites on the intracellular side of the membrane shows a distinct structural specificity, with binding of phosphatidic acid and phosphatidylglycerol being stronger than binding of phosphatidylcholine, whereas binding constants for phosphatidylserine and cardiolipin are similar to that for phosphatidylcholine. It is suggested that this pattern of binding follows from the pattern of charge distribution on KcsA on the intracellular side of the membrane.
0006-3495
4081-4089
Marius, Phedra
f5bf8a27-2332-4d04-a45b-4b2677fcc865
Alvis, Simon J.
c88b0bb5-db39-4559-a62c-ac5d772b5009
East, J. Malcolm
9fe7f794-1d89-4935-9a99-b831d786056e
Lee, Anthony G.
0891914c-e0e2-4ee1-b43e-1b70eb072d8e
Marius, Phedra
f5bf8a27-2332-4d04-a45b-4b2677fcc865
Alvis, Simon J.
c88b0bb5-db39-4559-a62c-ac5d772b5009
East, J. Malcolm
9fe7f794-1d89-4935-9a99-b831d786056e
Lee, Anthony G.
0891914c-e0e2-4ee1-b43e-1b70eb072d8e

Marius, Phedra, Alvis, Simon J., East, J. Malcolm and Lee, Anthony G. (2005) The interfacial lipid binding site on the potassium channel KcsA is specific for anionic phospholipids. Biophysical Journal, 89 (6), 4081-4089. (doi:10.1529/biophysj.105.070755).

Record type: Article

Abstract

Lipid binding to the potassium channel KcsA from Streptomyces lividans has been studied using quenching of the fluorescence of Trp residues by brominated phospholipids. It is shown that binding of phospholipids to nonannular lipid binding sites on KcsA, located one each at the four protein-protein interfaces in the tetrameric structure, is specific for anionic phospholipids, zwitterionic phosphatidylcholine being unable to bind at the sites. The binding constant for phosphatidylglycerol of 3.0 ± 0.7 mol fraction–1 means that in a membrane containing ~20 mol% phosphatidylglycerol, as in the Escherichia coli inner membrane, the nonannular sites will be ~37% occupied by phosphatidylglycerol. The binding constant for phosphatidic acid is similar to that for phosphatidylglycerol but binding constants for phosphatidylserine and cardiolipin are about double those for phosphatidylglycerol. Binding to annular sites around the circumference of the KcsA tetramer are different on the extracellular and intracellular faces of the membrane. On the extracellular face of the membrane the binding constants for anionic lipids are similar to those for phosphatidylcholine, the lack of specificity being consistent with the lack of any marked clusters of charged residues on KcsA close to the membrane on the extracellular side. In contrast, binding to annular sites on the intracellular side of the membrane shows a distinct structural specificity, with binding of phosphatidic acid and phosphatidylglycerol being stronger than binding of phosphatidylcholine, whereas binding constants for phosphatidylserine and cardiolipin are similar to that for phosphatidylcholine. It is suggested that this pattern of binding follows from the pattern of charge distribution on KcsA on the intracellular side of the membrane.

Text
A.G.Lee_KcsA.(4)pdf.pdf - Other
Restricted to Registered users only
Download (620kB)
Request a copy

More information

Published date: 1 December 2005

Identifiers

Local EPrints ID: 28749
URI: https://eprints.soton.ac.uk/id/eprint/28749
ISSN: 0006-3495
PURE UUID: 9b4b5ccb-b928-4d80-8b0e-dbdd3f494b78

Catalogue record

Date deposited: 05 May 2006
Last modified: 15 Jul 2019 19:10

Export record

Altmetrics

Download statistics

Downloads from ePrints over the past year. Other digital versions may also be available to download e.g. from the publisher's website.

View more statistics

Atom RSS 1.0 RSS 2.0

Contact ePrints Soton: eprints@soton.ac.uk

ePrints Soton supports OAI 2.0 with a base URL of https://eprints.soton.ac.uk/cgi/oai2

This repository has been built using EPrints software, developed at the University of Southampton, but available to everyone to use.

We use cookies to ensure that we give you the best experience on our website. If you continue without changing your settings, we will assume that you are happy to receive cookies on the University of Southampton website.

×