scholarly journals Measuring Transmembrane Helix Interaction Strengths in Lipid Bilayers Using Steric Trapping

2013 ◽  
pp. 37-56 ◽  
Author(s):  
Heedeok Hong ◽  
Yu-Chu Chang ◽  
James U. Bowie
Keyword(s):  
Lipid Bilayers ◽  
Transmembrane Helix

scholarly journals Visualization of lipid bilayer in the crystals by solvent contrast modulation

2014 ◽  
Vol 70 (a1) ◽  
pp. C1498-C1498
Author(s):  
Yoshiyuki Norimatsu ◽  
Junko Tsueda ◽  
Ayami Hirata ◽  
Shiho Iwasawa ◽  
Chikashi Toyoshima
Keyword(s):  
Lipid Bilayer ◽  
Electron Density ◽  
Lipid Bilayers ◽  
Transmembrane Helix ◽  
Real Space ◽  
New Method ◽  
Imaging Plate ◽  
Salt Bridges ◽  
Transmembrane Helices ◽  
X Ray

A new method of X-ray solvent contrast modulation was developed to visualize lipid bilayers in crystals of membrane proteins at a high enough resolution to resolve individual phospholipids molecules (~3.5 Å ). Visualization of lipid bilayer has been escaping from conventional crystallographic methods due to its extreme flexibility, and our knowledge on the behavior of lipid bilayer is still very much limited. Here we applied the new method of X-ray solvent contrast modulation to crystals of Ca2+-ATPase in 4 different physiological states. As phospholipids have to be added to make crystals of Ca2+-ATPase, it is expected that lipid bilayers are present in the crystals. Moreover, transmembrane helices of Ca2+-ATPase rearrange drastically during the reaction cycle and some of them show substantial movements perpendicular to the bilayer plane. Thus these crystals provide a rare opportunity to directly visualize phospholipids interacting with a membrane protein in different conformations. Complete diffraction data covering from 200 to 3.2 Å resolution were collected at BL41XU, Spring-8, using an R-Axis V imaging plate detector for crystals soaked in solvent of different electron density. A new concept "solvent exchange probability", which should be 1 in the bulk solvent, 0 inside the protein and an intermediate at interface, was introduced and used as a restraint for real space phase improvement. The electron density maps thus obtained clearly show that: (i) Phospholipid molecules surrounding the protein are fixed apparently by Arg/Lys-phosphate salt bridges or Trp-carbonyl hydrogen bonds and follow the movements of transmembrane helices. Movements of as large as 12 Å are allowed. (ii) If the movement of a transmembrane helix exceeds this limit, associated phospholipids change the partners for fixation or change the orientation of the entire protein molecule.

scholarly journals Stability and self aggregation of a model transmembrane helix in lipid bilayers

2000 ◽  
Vol 40 (supplement) ◽  
pp. S132
Author(s):  
Y. Yano ◽  
T. Takemoto ◽  
S Kobayashi ◽  
W. Ohashi ◽  
M. Niwa ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Transmembrane Helix ◽  
Self Aggregation

scholarly journals State-dependent mapping of GlyR-cholesterol interactions by coupling crosslinking with mass spectrometry

2020 ◽  
Author(s):  
Nicholas A. Ferraro ◽  
Michael Cascio
Keyword(s):  
Mass Spectrometry ◽  
Lipid Bilayers ◽  
Glycine Receptor ◽  
Transmembrane Helix ◽  
Covalent Attachment ◽  
Channel Dynamics ◽  
State Dependent ◽  
Extracellular Region ◽  
Lipid Environment ◽  
And Function

AbstractPentameric ligand-gated ion channel (pLGIC) allostery is dependent on dynamic associations with its diverse environment. The cellular membrane’s lipid composition influences channel function with cholesterol being a key regulator of channel activity. Human α1 glycine receptor (GlyR) was purified from baculovirus infected insect cells and reconstituted in unilamellar vesicles at physiological cholesterol:lipid ratios with aliquots of azi-cholesterol, a photoactivatable non-specific crosslinker. The receptor in vesicles was then enriched in either a resting, open, or desensitized state prior to photocrosslinking. Following photoactivation, crosslinked cholesterol-GlyR was trypsinized and sites of direct covalent attachment to peptides were identified by targeted MS/MS. Dozens of state-dependent crosslinks were identified and differential patterns of cholesterol-GlyR crosslinks were observed in the extracellular region nearing the lipid bilayer, in the M4 transmembrane helix, and in the large intracellular M3-M4 loop. Unique crosslinks in comparative studies identify changes in lipid accessibility or modulation of hydrophobic cavities in GlyR as a function of receptor allostery. Most notably, the outward twisting of M4 and differential crosslinking within the M3-M4 loop provide new insight into allosteric repositioning of GlyR. More generally, this study provides an accurate and sensitive approach to mapping the protein-lipid interactions to discern state-dependent structural movements of membrane proteins embedded in lipid-bilayers.SignificanceIon channels are highly allosteric molecular machines whose structure and function are sensitive to lipids and ligands. While the structures of many pLGICs are known, these are often truncated forms of the receptor in a membrane-mimetic environment locked in ligand-bound conformational states that may not accurately reflect the conformation and dynamics of the receptor in a native lipid environment. Crosslinking coupled with mass spectrometry (CX-MS) has the capability of interrogating the structure of full-length receptors in a lipid environment. In this study, CX-MS was used to identify state-dependent cholesterol-GlyR interactions to identify differential cholesterol accessibility as a function of channel dynamics upon gating and desensitization.

Modulation of glycophorin A transmembrane helix interactions by lipid bilayers: molecular dynamics calculations

2000 ◽  
Vol 302 (3) ◽  
pp. 727-746 ◽  
Author(s):  
Horia I Petrache ◽  
Alan Grossfield ◽  
Kevin R MacKenzie ◽  
Donald M Engelman ◽  
Thomas B Woolf
Keyword(s):  
Molecular Dynamics ◽  
Lipid Bilayers ◽  
Transmembrane Helix ◽  
Glycophorin A ◽  
Molecular Dynamics Calculations ◽  
Helix Interactions

scholarly journals Interaction of a two-transmembrane-helix peptide with lipid bilayers and dodecyl sulfate micelles

2011 ◽  
Vol 159 (2-3) ◽  
pp. 321-327 ◽  
Author(s):  
Robert Renthal ◽  
Lorenzo Brancaleon ◽  
Isaac Peña ◽  
Frances Silva ◽  
Liao Y. Chen
Keyword(s):  
Lipid Bilayers ◽  
Transmembrane Helix ◽  
Dodecyl Sulfate
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