Modulation of folding and assembly of the membrane protein bacteriorhodopsin by intermolecular forces within the lipid bilayer

  • Curran A
  • Templer R
  • Booth P
  • 56

    Readers

    Mendeley users who have this article in their library.
  • 102

    Citations

    Citations of this article.

Abstract

Three different lipid systems have been developed to investigate the effect of physicochemical forces within the lipid bilayer on the folding of the integral membrane protein bacteriorhodopsin. Each system consists of lipid vesicles containing two lipid species, one with phosphatidylcholine and the other with phosphatidylethanolamine headgroups, but the same hydrocarbon chains: either L-alpha-1, 2-dioleoyl, L-alpha-1,2-dipalmitoleoyl, or L-alpha-1,2-dimyristoyl. Increasing the mole fraction of the phosphatidylethanolamine lipid increases the desire of each monolayer leaflet in the bilayer to curve toward water. This increases the torque tension of such monolayers, when they are constrained to remain flat in the vesicle bilayer. Consequently, the lateral pressure in the hydrocarbon chain region increases, and we have used excimer fluorescence from pyrene-labeled phosphatidylcholine lipids to probe these pressure changes. We show that bacteriorhodopsin regenerates to about 95% yield in vesicles of 100% phosphatidylcholine. The regeneration yield decreases as the mole fraction of the corresponding phosphatidylethanolamine component is increased. The decrease in yield correlates with the increase in lateral pressure which the lipid chains exert on the refolding protein. We suggest that the increase in lipid chain pressure either hinders insertion of the denatured state of bacterioopsin into the bilayer or slows a folding step within the bilayer, to the extent that an intermediate involved in bacteriorhodopsin regeneration is effectively trapped.

Get free article suggestions today

Mendeley saves you time finding and organizing research

Sign up here
Already have an account ?Sign in

Find this document

Authors

  • A. Rachael Curran

  • Richard H. Templer

  • Paula J. Booth

Cite this document

Choose a citation style from the tabs below

Save time finding and organizing research with Mendeley

Sign up for free