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Different effects of lipid chain length on the two sides of a membrane and the lipid annulus of MscL

Different effects of lipid chain length on the two sides of a membrane and the lipid annulus of MscL
Different effects of lipid chain length on the two sides of a membrane and the lipid annulus of MscL
Quenching of the fluorescence of Trp residues in a membrane protein by lipids with bromine-containing fatty acyl chains provides a powerful technique for measuring lipid-protein binding constants. Single Trp residues have been placed on the periplasmic and cytoplasmic sides of the mechanosensitive channel of large conductance MscL from Mycobacterium tuberculosis to measure, separately, lipid binding constants on the two faces of MscL. The chain-length dependence of lipid binding was found to be different on the two sides of MscL, the chain-length dependence being more marked on the cytoplasmic than on the periplasmic side. To determine if lipid binding constants are affected by the properties of the lipid molecules not in direct contact with MscL (the bulk lipid), the amount of bulk lipid present in the system was varied. The binding constant of the short-chain phospholipid didodecylphosphatidylcholine was found to be independent of the molar ratio of lipid/MscL pentamer over the range 500:1–50:1, suggesting that lipid binding constants are determined largely by the properties of the lipid molecules interacting directly with MscL. These results point to a model in which lipid molecules located on the transmembrane surface of a membrane protein (the annular lipid molecules), by playing a dominant role in the interaction between a membrane protein and the surrounding lipid bilayer, could effectively buffer the membrane protein from changes in the properties of the bulk lipid bilayer.
0006-3495
113-122
Powl, A.M.
58e5cab2-1c71-412b-97ca-39604b73b08c
East, J.M.
9fe7f794-1d89-4935-9a99-b831d786056e
Lee, A.G.
0891914c-e0e2-4ee1-b43e-1b70eb072d8e
Powl, A.M.
58e5cab2-1c71-412b-97ca-39604b73b08c
East, J.M.
9fe7f794-1d89-4935-9a99-b831d786056e
Lee, A.G.
0891914c-e0e2-4ee1-b43e-1b70eb072d8e

Powl, A.M., East, J.M. and Lee, A.G. (2007) Different effects of lipid chain length on the two sides of a membrane and the lipid annulus of MscL. Biophysical Journal, 93 (1), 113-122. (doi:10.1529/biophysj.107.105130).

Record type: Article

Abstract

Quenching of the fluorescence of Trp residues in a membrane protein by lipids with bromine-containing fatty acyl chains provides a powerful technique for measuring lipid-protein binding constants. Single Trp residues have been placed on the periplasmic and cytoplasmic sides of the mechanosensitive channel of large conductance MscL from Mycobacterium tuberculosis to measure, separately, lipid binding constants on the two faces of MscL. The chain-length dependence of lipid binding was found to be different on the two sides of MscL, the chain-length dependence being more marked on the cytoplasmic than on the periplasmic side. To determine if lipid binding constants are affected by the properties of the lipid molecules not in direct contact with MscL (the bulk lipid), the amount of bulk lipid present in the system was varied. The binding constant of the short-chain phospholipid didodecylphosphatidylcholine was found to be independent of the molar ratio of lipid/MscL pentamer over the range 500:1–50:1, suggesting that lipid binding constants are determined largely by the properties of the lipid molecules interacting directly with MscL. These results point to a model in which lipid molecules located on the transmembrane surface of a membrane protein (the annular lipid molecules), by playing a dominant role in the interaction between a membrane protein and the surrounding lipid bilayer, could effectively buffer the membrane protein from changes in the properties of the bulk lipid bilayer.

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Published date: 1 July 2007

Identifiers

Local EPrints ID: 56777
URI: http://eprints.soton.ac.uk/id/eprint/56777
ISSN: 0006-3495
PURE UUID: 28cd0a14-6954-45d2-9ec0-0701ad2c9280

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Date deposited: 07 Aug 2008
Last modified: 15 Mar 2024 11:03

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Contributors

Author: A.M. Powl
Author: J.M. East
Author: A.G. Lee

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