Is There a Preferential Interaction between Cholesterol and Tryptophan Residues in Membrane Proteins? Export

@article{citeulike:2425409, abstract = {Abstract: Recently, several indications have been found that suggest a preferential interaction between cholesterol and tryptophan residues located near the membrane-water interface. The aim of this study was to investigate by direct methods how tryptophan and cholesterol interact with each other and what the possible consequences are for membrane organization. For this purpose, we used cholesterol-containing model membranes of dimyristoylphosphatidylcholine (DMPC) in which a transmembrane model peptide with flanking tryptophans [acetyl-GWW(LA)8LWWA-amide], called WALP23, was incorporated to mimic interfacial tryptophans of membrane proteins. These model systems were studied with two complementary methods. (1) Steady-state and time-resolved F\"{o}rster resonance energy transfer (FRET) experiments employing the fluorescent cholesterol analogue dehydroergosterol (DHE) in combination with a competition experiment with cholesterol were used to obtain information about the distribution of cholesterol in the bilayer in the presence of WALP23. The results were consistent with a random distribution of cholesterol which indicates that cholesterol and interfacial tryptophans are not preferentially located next to each other in these bilayer systems. (2) Solid-state 2H NMR experiments employing either deuterated cholesterol or indole ring-deuterated WALP23 peptides were performed to study the orientation and dynamics of both molecules. The results showed that the quadrupolar splittings of labeled cholesterol were not affected by an interaction with tryptophan-flanked peptides and, vice versa, that the quadrupolar splittings of labeled indole rings in WALP23 are not significantly influenced by addition of cholesterol to the bilayer. Therefore, both NMR and fluorescence spectroscopy results independently show that, at least in the model systems studied here, there is no evidence for a preferential interaction between cholesterol and tryptophans located at the bilayer interface.}, address = {Chemical Biology and Organic Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands, Medicinal Chemistry and Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands, Centro de Qu\'{\i}mica-F\'{\i}sica Molecular, Complexo Interdisciplinar, Instituto Superior T\'{e}cnico, Av. Rovisco Pais, 1049-001 Lisbon, Portugal, Faculdade de Farmcia da Universidade de Coimbra, 3000-295 Coimbra, Portugal, and Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701}, author = {Holt, A. and Dealmeida, R. F. M. and Nyholm, T. K. M. and Loura, L. M. S. and Daily, A. E. and Staffhorst, R. W. H. M. and Rijkers, D. T. S. and Koeppe, R. E. and Prieto, M. and Killian, J. A.}, citeulike-article-id = {2425409}, citeulike-linkout-0 = {http://dx.doi.org/10.1021/bi702235k}, citeulike-linkout-1 = {http://pubs.acs.org/doi/abs/10.1021/bi702235k}, day = {26}, doi = {10.1021/bi702235k}, journal = {Biochemistry}, keywords = {cholesterol, membrane\_protein, tryptophan}, month = {February}, number = {8}, pages = {2638--2649}, posted-at = {2008-05-14 11:50:04}, priority = {2}, title = {Is There a Preferential Interaction between Cholesterol and Tryptophan Residues in Membrane Proteins?}, url = {http://dx.doi.org/10.1021/bi702235k}, volume = {47}, year = {2008} }

TY - JOUR ID - citeulike:2425409 L3 - citeulike-article-id:2425409 N2 - Abstract: Recently, several indications have been found that suggest a preferential interaction between cholesterol and tryptophan residues located near the membrane-water interface. The aim of this study was to investigate by direct methods how tryptophan and cholesterol interact with each other and what the possible consequences are for membrane organization. For this purpose, we used cholesterol-containing model membranes of dimyristoylphosphatidylcholine (DMPC) in which a transmembrane model peptide with flanking tryptophans [acetyl-GWW(LA)8LWWA-amide], called WALP23, was incorporated to mimic interfacial tryptophans of membrane proteins. These model systems were studied with two complementary methods. (1) Steady-state and time-resolved Förster resonance energy transfer (FRET) experiments employing the fluorescent cholesterol analogue dehydroergosterol (DHE) in combination with a competition experiment with cholesterol were used to obtain information about the distribution of cholesterol in the bilayer in the presence of WALP23. The results were consistent with a random distribution of cholesterol which indicates that cholesterol and interfacial tryptophans are not preferentially located next to each other in these bilayer systems. (2) Solid-state 2H NMR experiments employing either deuterated cholesterol or indole ring-deuterated WALP23 peptides were performed to study the orientation and dynamics of both molecules. The results showed that the quadrupolar splittings of labeled cholesterol were not affected by an interaction with tryptophan-flanked peptides and, vice versa, that the quadrupolar splittings of labeled indole rings in WALP23 are not significantly influenced by addition of cholesterol to the bilayer. Therefore, both NMR and fluorescence spectroscopy results independently show that, at least in the model systems studied here, there is no evidence for a preferential interaction between cholesterol and tryptophans located at the bilayer interface. IS - 8 JF - Biochemistry AD - Chemical Biology and Organic Chemistry, Bijvoet Center for Biomolecular Research, Utrecht University, Padualaan 8, 3584 CH Utrecht, The Netherlands, Medicinal Chemistry and Chemical Biology, Utrecht Institute for Pharmaceutical Sciences, Utrecht University, Sorbonnelaan 16, 3584 CA Utrecht, The Netherlands, Centro de Química-Física Molecular, Complexo Interdisciplinar, Instituto Superior Técnico, Av. Rovisco Pais, 1049-001 Lisbon, Portugal, Faculdade de Farmcia da Universidade de Coimbra, 3000-295 Coimbra, Portugal, and Department of Chemistry and Biochemistry, University of Arkansas, Fayetteville, Arkansas 72701 EP - 2649 TI - Is There a Preferential Interaction between Cholesterol and Tryptophan Residues in Membrane Proteins? VL - 47 SP - 2638 KW - cholesterol KW - membrane_protein KW - tryptophan AU - Holt, A AU - Dealmeida, RFM AU - Nyholm, TKM AU - Loura, LMS AU - Daily, AE AU - Staffhorst, RWHM AU - Rijkers, DTS AU - Koeppe, RE AU - Prieto, M AU - Killian, JA PY - 2008/02/26/ UR - http://dx.doi.org/10.1021/bi702235k ER -