Lipid lateral mobility and membrane phase structure modulation by protein binding.
Using a combination of fluorescence correlation and infrared absorption spectroscopies, we characterize lipid lateral diffusion and membrane phase structure as a function of protein binding to the membrane surface. In a supported membrane configuration, cholera toxin binding to the pentasaccharaide headgroup of membrane-incorporated GM1 lipid alters the long-range lateral diffusion of fluorescently labeled probe lipids, which are not involved in the binding interaction. This effect is prominently amplified near the gel-fluid transition temperature, Tm, of the majority lipid component. At temperatures near Tm, large changes in probe lipid diffusion are measured at average protein coverage densities as low as 0.02 area fraction. Spectral shifts of the methylene symmetric and asymmetric stretching modes in the lipid acyl chain confirm that protein binding alters the fraction of lipid in the gel phase.
Forstner
Martin B
MB
Department of Chemistry, University of California, Berkeley, California 94720, USA.
Yee
Chanel K
CK
Parikh
Atul N
AN
Groves
Jay T
JT
D002772:Cholera Toxin / Q000737:chemistry* / Q000378:metabolism; D004058:Diffusion; D004134:Dimyristoylphosphatidylcholine / Q000737:chemistry; D005677:G(M1) Ganglioside / Q000737:chemistry* / Q000378:metabolism; D007700:Kinetics; D008051:Lipid Bilayers / Q000737:chemistry / Q000378:metabolism; D008560:Membrane Fluidity; D008563:Membrane Lipids / Q000737:chemistry* / Q000378:metabolism; D008958:Models, Molecular; D011485:Protein Binding; D017550:Spectroscopy, Fourier Transform Infrared
D008051:Lipid Bilayers; D008563:Membrane Lipids; D005677:G(M1) Ganglioside; D002772:Cholera Toxin; D004134:Dimyristoylphosphatidylcholine