Stoichiometry and specificity of lipid-protein interaction with myelin proteolipid protein studied by spin-label electron spin resonance

Brophy, Peter; Horváth, László; Marsh, Derek

doi:10.1021/bi00300a011

Cited by 84 publications

(86 citation statements)

References 21 publications

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“…It is found that the protein has very little effect on either the degree of order of the lipid chain or the population of gauche rotational isomers but increases the rotational correlation times for chain fluctuation, chain rotation, and trans-gauche isomerism by a factor of 10 or more. These results are fully consistent with those obtained from ESR spectroscopy of spin-labeled lipids (6,7). …”

supporting

confidence: 91%

Integral membrane proteins significantly decrease the molecular motion in lipid bilayers: a deuteron NMR relaxation study of membranes containing myelin proteolipid apoprotein.

Meier¹,

Sachse²,

Brophy³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

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The influence of the myelin proteolipid apoprotein on lipid chain order and dynamics was studied by 2H NMR of membranes reconstituted with specifically deuterated dimyristoyl phosphatidylcholines. Quadrupolar echo and saturation recovery experiments were fitted by numerical solution of the stochastic Liouville equation, using a model that includes both inter-and intramolecular motions [Meier, P., Ohmes, E. & Kothe, G. (1986) J. Chem. Phys. 85,[3598][3599][3600][3601][3602][3603][3604][3605][3606][3607][3608][3609][3610][3611][3612][3613][3614]. Combined simulations of both the relaxation times and the quadrupolar echo line shapes as a function of pulse spacing allowed unambiguous assignment of the various motional modes and a consistent interpretation of data from lipids labeled on the C-6, C-13, and C-14 positions of the sn-2 chain. In the fluid phase, the protein has little influence on either the chain order or the population of gauche rotational isomers but strongly retards the chain dynamics. Lipid-protein interactions are important determinants of biological membrane structure and function and, for this reason, have been the subject of intensive study by physicochemical methods. Magnetic resonance spectroscopy has made major contributions in this area because of its unique sensitivity to anisotropic molecular motion. and 3).The complexity of the systems involved dictates that a detailed description of the effects of integral membrane proteins on lipid chain dynamics can best be achieved by a combination of multipulse NMR experiments with comprehensive theoretical simulations. Such an analysis is currently lacking. In the present work, we have investigated myelin proteolipid apoprotein reconstituted with specifically deuterated dimyristoyl phosphatidylcholine ([Myr2]PtdCho) as a model system for lipid-protein interactions in biological membranes. A motional model has been employed that includes both inter-and intramolecular motion (i.e., both long-axis motion and trans-gauche isomerization) and which is valid in both fast and slow motional regimes (4,5). The simulation of quadrupole echo spectra as a function of pulse spacing, together with measurements of spin-lattice relaxation time (Tz), allows discrimination of the different motional modes, leading to an unambiguous description of the molecular dynamics. A consistent interpretation is obtained of data from reconstitutions with [Myr2]PtdCho labeled at the C-6, -13, and -14 atoms of the sn-2 chain. It is found that the protein has very little effect on either the degree of order of the lipid chain or the population of gauche rotational isomers but increases the rotational correlation times for chain fluctuation, chain rotation, and trans-gauche isomerism by a factor of 10 or more. These results are fully consistent with those obtained from ESR spectroscopy of spin-labeled lipids (6, 7). 3704The publication costs of this article were defrayed in part by page charge payment. This article must therefore be hereby marked "advertisement" in accordan...

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supporting

confidence: 91%

Integral membrane proteins significantly decrease the molecular motion in lipid bilayers: a deuteron NMR relaxation study of membranes containing myelin proteolipid apoprotein.

Meier¹,

Sachse²,

Brophy³

et al. 1987

Proc. Natl. Acad. Sci. U.S.A.

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“…This oligomerisation of the proteolipid proteins has been reported previously; using electron spin resonance, Brophy et al (1984) suggested a possible hexameric complex to account for the smaller than expected number of lipids associated with the protein. Using ultracentifugation, Smith et al (1984) also suggested a hexameric complex, whereas Lavaille et al (1979) showed that PLP is not monomeric in 2-chloroethanol.…”

Section: Introductionsupporting

confidence: 82%

Evidence for possible interactions between PLP and DM20 within the myelin sheath

McLaughlin¹,

Hunter²,

Thomson³

et al. 2002

Glia

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PLP and its smaller DM20 isoform constitute the major proteins of CNS myelin. Previous studies indicated a role for the proteins in maintaining the intraperiod line of the myelin sheath and the integrity of axons and suggested that both isoforms were necessary to provide these functions. The present study shows that each isoform is capable individually of inserting into compact myelin. Employing chromatographic extraction procedures designed to maintain the natural conformation of the proteins we found that most PLP and DM20 remained associated. Using an antibody specific to the PLP isoform, we were able to co-immunoprecipitate DM20 from the major fraction of the extracted equine myelin and from mouse native whole myelin. We suggest that PLP and DM20 may form a hetero-oligomeric complex within the myelin sheath, probably in association with specific lipids and that this arrangement is essential for the normal structure of myelin and axons.

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“…In addition, our figures are also similar to those proposed by Curatolo et al [lo], who estimated in 30 lipids the number of Myr2GroPCho molecules that could be accommodated around the PLA molecule, the latter idealised as a circular cylinder not protruding into the aqueous phase. However Brophy et al [7], on the basis of ESR spectroscopy, have…”

Section: Fluorescence Studiesmentioning

confidence: 99%

Lipid–protein interaction

Goñi

Cozar

Alonso

et al. 1988

European Journal of Biochemistry

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Bovine myelin proteolipid apoprotein (PLA), obtained in high yield and purity by a novel ultrafiltration procedure, has been used to study the perturbations produced by this protein on phosphatidylcholine bilayers, using infrared spectroscopy, nuclear magnetic resonance and fluorescence polarisation. PLA interacts with phospholipids in a similar manner to other intrinsic proteins. For bilayers in the fluid state, the fatty-acyl chain static order, as measured by deuterium NMR, is slightly increased in the presence of the protein, except at very high PLA concentrations. Phosphorus NMR reveals some perturbation of the phospholipid polar group by PLA, but to a smaller degree than occurs with other intrinsic proteins. An increase in static order above t , (the onset temperature for gel-to-fluid transition) is also detected by infrared spectroscopy. Studies using steady-state polarisation of diphenylhexatriene fluorescence indicate that the microviscosity of the bilayer increases as a function of the protein mole fraction. From these data an estimation of the average number of lipids perturbed per protein monomer has been made, and a figure of 37 phospholipid molecules determined. The data are compatible with a picture of a hydrophobic polypeptide, perturbing the phospholipids close to it, but allowing rapid (> lo4 s-') exchange with all the lipid molecules in the system.The interactions between phospholipids and intrinsic proteins in model and cell membranes have been the object of many studies in the past years [I-31. In general the preparation of suitable samples for such studies requires that phospholipid and protein be solubilised together, with the help of organic solvents or the use of detergents, upon removal of which the protein-containing bilayers from spontaneously in an aqueous medium [4, 51. The use of organic solvents is most convenient. Studies involving organic solvents have been carried out previously with the short peptide gramicidin A [5] and in earlier studies with the myelin proteolipid apoprotein (PLA) [6, 71. However, in general only very hydrophobic intrinsic proteins can be solubilised in this way without major loss of structural properties. PLA in particular has been extensively used in studies on lipid -protein interaction. PLA/ phospholipid/water systems have been explored at least from the point of view of ultrastructural [S, 91, calorimetric [9, 101 and spectroscopic [7, 3 1, 321 techniques. Recently a strongly documented deuteron nuclear magnetic resonance (NMR) study of this system has been published [13].In this paper we report our studies using a variety of physical techniques: infrared, deuteron NMR and fluorescence polarisation spectroscopy, in order to describe the efCovresponhce to F. M. Got%, Departamento de Bioquimica, Universidad del Pais Vasco, Apartado 644, E-48080 Bilbao, Spain A hbveviutions. M yr'GroPCho, 1,2-dimyristoyl-sn-glycero-3-phosphocholine; PLA, proteolipid apoprotein; AVQ, deuterium quadrupole splitting; 6, half width at half height of a spectral line; P, fluore...

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Stoichiometry and specificity of lipid-protein interaction with myelin proteolipid protein studied by spin-label electron spin resonance

Cited by 84 publications

References 21 publications

Integral membrane proteins significantly decrease the molecular motion in lipid bilayers: a deuteron NMR relaxation study of membranes containing myelin proteolipid apoprotein.

Integral membrane proteins significantly decrease the molecular motion in lipid bilayers: a deuteron NMR relaxation study of membranes containing myelin proteolipid apoprotein.

Evidence for possible interactions between PLP and DM20 within the myelin sheath

Lipid–protein interaction

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