This Article Full Text Full Text (PDF) All Versions of this Article: biophysj.106.102210v1 92/10/3556    most recent Alert me when this article is cited Alert me if a correction is posted Services Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Google Scholar Articles by Carney, J. Articles by Lee, A. G. Search for Related Content PubMed PubMed Citation Articles by Carney, J. Articles by Lee, A. G.

Penetration of Lipid Chains into Transmembrane Surfaces of Membrane Proteins: Studies with MscL

School of Biological Sciences, University of Southampton, Southampton, SO16 7PX, United Kingdom

Correspondence: Address reprint requests to Prof. A. G. Lee, School of Biological Sciences, University of Southampton, Southampton, SO16 7PX, UK. Tel.: 44-0-2380-594331; Fax: 44-0-2380-594459; E-mail: agl{at}soton.ac.uk.

The transmembrane surface of a multi-helix membrane protein will be rough with cavities of various sizes between the transmembrane -helices. Efficient solvation of the surface by the lipid molecules that surround the protein in a membrane requires that the lipid fatty acyl chains be able to enter the cavities. This possibility has been investigated using fluorescence quenching methods. Trp residues have been introduced into lipid-facing sites in the first transmembrane -helix (M1) of the mechanosensitive channel of large-conductance MscL; lipid-facing residues at the N-terminal end of M1 are buried below the transmembrane surface of the protein. Fluorescence emission maxima for lipid-facing Trp residues in M1 vary with position in the bilayer comparably to those for Trp residues in the second transmembrane -helix (M2) despite the fact that lipid-facing residues in M2 are on the surface of the protein. Fluorescence emission spectra for most Trp residues on the periplasmic sides of M1 and M2 fit well to a model proposing a trough-like variation of dielectric constant across the membrane, but the relationship between location and fluorescence emission maximum on the cytoplasmic side of the membrane is more complex. The fluorescence of Trp residues in M1 is quenched efficiently by phospholipids with bromine-containing fatty acyl chains, showing that the lipid chains must be able to enter the Trp-containing cavities on the surface of MscL, resulting in efficient solvation of the surface.

This article has been cited by other articles:

				P. Marius, M. Zagnoni, M. E. Sandison, J. M. East, H. Morgan, and A. G. Lee Binding of Anionic Lipids to at Least Three Nonannular Sites on the Potassium Channel KcsA is Required for Channel Opening Biophys. J., March 1, 2008; 94(5): 1689 - 1698. [Abstract] [Full Text] [PDF]