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Gramicidin-based Fluorescence Assay; for Determining Small Molecules Potential for Modifying Lipid Bilayer Properties
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Lipid bilayer composition influences small multidrug transporters

Kalypso Charalambous1, David Miller, Paul Curnow

  • 1Department of Biochemistry, University of Bristol, Bristol BS8 1TD, UK. k.charalambous@mail.cryst.bbk.ac.uk

BMC Biochemistry
|November 27, 2008
PubMed
Abstract

Insights

Membrane lipid composition significantly impacts the function of small multidrug resistance transporters EmrE and TBsmr. Phosphatidylethanolamine and anionic lipids enhance methyl viologen transport activity by altering bilayer forces.

Area of Science:

  • Biochemistry
  • Membrane Biology
  • Structural Biology

Background:

  • Membrane proteins, including transporters, are modulated by their lipid environment.
  • The small multidrug resistance (SMR) family members EmrE (Escherichia coli) and TBsmr (Mycobacterium tuberculosis) are investigated.
  • Lipid bilayer properties, such as lateral pressure, influence membrane protein function.

Purpose of the Study:

  • To investigate the effect of bilayer composition on the transport activity of EmrE and TBsmr.
  • To determine the influence of phosphatidylethanolamine and anionic lipids on these transporters.
  • To understand how membrane physical state affects multidrug transport.

Main Methods:

  • Investigated transport activity of EmrE and TBsmr in varying lipid compositions.
  • Utilized phosphatidylethanolamine and anionic lipids (phosphatidylglycerol, phosphatidylinositol).
  • Assessed methyl viologen transport in reconstituted systems.

Main Results:

  • Both EmrE and TBsmr showed increased methyl viologen transport with phosphatidylethanolamine.
  • Anionic lipids also enhanced transport for both transporters.
  • Proteins exhibited a preference for their native anionic lipid headgroups: phosphatidylglycerol for EmrE and phosphatidylinositol for TBsmr.

Conclusions:

  • The physical state of the membrane alters drug transport activity.
  • Substrate translocation by these transporters is dependent on in vitro lipid composition.
  • Multidrug transporter activity is responsive to changes in lateral forces exerted by the lipid bilayer.

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