Article

When detergent meets bilayer: Birth and coming of age of lipid bicelles.

Biophysics and Department of Chemistry, University of Michigan, Ann Arbor, MI 48109-1055, USA.
Progress in Nuclear Magnetic Resonance Spectroscopy (Impact Factor: 8.71). 02/2013; 69:1-22. DOI: 10.1016/j.pnmrs.2013.01.001
Source: PubMed

ABSTRACT Graphical abstract
Figure optionsView in workspace

Highlights
► Lipid bicelles have matured to full membership in the club of lipid phases. ► Numerous techniques have elucidated the character traits of bicelles. ► Bicelles are exemplary citizens in the realm of model membranes. ► They contribute particularly in studies of membrane protein structure.

1 Bookmark
 · 
107 Views
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: bstract The effects of lipids on membrane proteins are likely to be complex and unique for each membrane protein. Here we studied different detergent/phosphatidylcholine reconstitution media and tested their effects on Plasma Membrane Ca2+-pump (PMCA). We found that Ca2+-ATPase activity has a biphasic behaviour respect to the detergent/phosphatidylcholine ratio, whose maximal value largely depends on the length and the unsaturation degree of the hydrocarbon chain. Using Static Light Scattering and Fluorescence Correlation Spectroscopy, we monitored the changes in hydrodynamic radius of detergent/phosphatidylcholine particles during the micelle-vesicle transition. We found that, when PMCA is reconstituted in mixed micelles, neutral phospholipids increase the enzyme turnover. The biophysical changes associated to the transition from mixed micelles to bicelles, increase the time of residence of the phosphorylated intermediate (EP) decreasing the enzyme turnover. Molecular Dynamics simulations analysis of the interactions between PMCA and the phospholipid bilayer in which it is embedded show that in the 1,2-dioleoyl-sn-glycero-3-phosphocholine (DOPC) bilayer, charged residues of the protein are trapped in the hydrophobic core. Conversely, in the 1,2-dimyristoyl-sn-glycero-3-phosphocholine (DMPC) bilayer, the overall hydrophobic-hydrophilic requirements of the protein surface are fulfilled the best, reducing the thermodynamic cost of exposing charged residues to the hydrophobic core. The apparent mismatch produced by a DOPC thicker bilayer, could be a structural foundation to explain its functional implication on PMCA. Copyright © 2015, The American Society for Biochemistry and Molecular Biology.
    Journal of Biological Chemistry 01/2015; pii: jbc.M114.585828. [. · 4.60 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: G protein-coupled receptors (GPCRs) have important roles in physiology and pathology, and 40% of drugs currently on the market target GPCRs for the treatment of various diseases. Because of their therapeutic importance, the structural mechanism of GPCR signaling is of great interest in the field of drug discovery. Hydrogen/deuterium exchange mass spectrometry (HDX-MS) is a useful tool for analyzing ligand binding sites, the protein-protein interaction interface, and conformational changes of proteins. However, its application to GPCRs has been limited for various reasons, including the hydrophobic nature of GPCRs and the use of detergents in their preparation. In the present study, we tested the application of bicelles as a means of solubilizing GPCRs for HDX-MS studies. GPCRs (e.g., β2-adrenergic receptor [β2AR], μ-opioid receptor, and protease-activated receptor 1) solubilized in bicelles produced better sequence coverage (greater than 90%) than GPCRs solubilized in n-dodecyl-β-D-maltopyranoside (DDM), suggesting that bicelles are a more effective method of solubilization for HDX-MS studies. The HDX-MS profile of β2AR in bicelles showed that transmembrane domains (TMs) undergo lower deuterium uptake than intracellular or extracellular regions, which is consistent with the fact that the TMs are highly ordered and embedded in bicelles. The overall HDX-MS profiles of β2AR solubilized in bicelles and in DDM were similar except for intracellular loop 3. Interestingly, we detected EX1 kinetics, an important phenomenon in protein dynamics, at the C-terminus of TM6 in β2AR. In conclusion, we suggest the application of bicelles as a useful method for solubilizing GPCRs for conformational analysis by HDX-MS.
    Journal of the American Society for Mass Spectrometry 03/2015; DOI:10.1007/s13361-015-1083-4 · 3.59 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: G protein-coupled receptors (GPCRs) have important roles in physiology and pathology, and 40% of drugs currently on the market target GPCRs for the treatment of various diseases. Because of their therapeutic importance, the structural mechanism of GPCR signaling is of great interest in the field of drug discovery. Hydrogen/deuterium exchange mass spectrometry (HDX-MS) is a useful tool for analyzing ligand binding sites, the protein–protein interaction interface, and confor-mational changes of proteins. However, its application to GPCRs has been limited for various reasons, including the hydrophobic nature of GPCRs and the use of detergents in their preparation. In the present study, we tested the application of bicelles as a means of solubilizing GPCRs for HDX-MS studies. GPCRs (e.g., β 2-adrenergic receptor [β 2 AR], μ-opioid receptor, and protease-activated receptor 1) solubilized in bicelles produced better sequence coverage (greater than 90%) than GPCRs solubilized in n-dodecyl-β-D-maltopyranoside (DDM), suggesting that bicelles are a more effective method of solubilization for HDX-MS studies. The HDX-MS profile of β 2
    Journal of the American Society for Mass Spectrometry 03/2015; · 3.59 Impact Factor

Full-text

Download
12 Downloads
Available from
Jul 21, 2014