Topological Stability and Self-Association of a Completely Hydrophobic Model Transmembrane Helix in Lipid Bilayers†

Biochemistry ◽  
2002 ◽  
Vol 41 (9) ◽  
pp. 3073-3080 ◽  
Author(s):  
Yoshiaki Yano ◽  
Tomokazu Takemoto ◽  
Satoe Kobayashi ◽  
Hiroyuki Yasui ◽  
Hiromu Sakurai ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Transmembrane Helix ◽  
Topological Stability ◽  
Self Association

Thermodynamics of Insertion and Self-Association of a Transmembrane Helix: A Lipophobic Interaction by Phosphatidylethanolamine

Biochemistry ◽  
2011 ◽  
Vol 50 (32) ◽  
pp. 6806-6814 ◽  
Author(s):  
Yoshiaki Yano ◽  
Arisa Yamamoto ◽  
Mai Ogura ◽  
Katsumi Matsuzaki
Keyword(s):  
Transmembrane Helix ◽  
Self Association

Viral Fusion Peptides: A Tool Set to Disrupt and Connect Biological Membranes

2000 ◽  
Vol 20 (6) ◽  
pp. 501-518 ◽  
Author(s):  
Lukas K. Tamm ◽  
Xing Han
Keyword(s):  
Lipid Bilayers ◽  
Biological Membrane ◽  
Membrane Curvature ◽  
Current Evidence ◽  
Viral Fusion ◽  
Fusion Peptides ◽  
Membrane Surfaces ◽  
Self Association ◽  
Α Helix ◽  
And Function

The structure and function of viral fusion peptides are reviewed. The fusion peptides of influenza virus hemagglutinin and human immunodeficiency virus are used as paradigms. Fusion peptides associated with lipid bilayers are conformationally polymorphic. Current evidence suggests that the fusion-promoting state is the obliquely inserted α-helix. Fusion peptides also have a tendency to self-associate into γ-sheets at membrane surfaces. Although the conformational conversion between α- and γ-states is reversible under controlled conditions, its physiological relevance is not yet known. The energetics of peptide insertion and self-association could be measured recently using more soluble “second generation” fusion peptides. Fusion peptides have been reported to change membrane curvature and the state of hydration of membrane surfaces. The combined results are built into a model for the mechanism by which fusion peptides are proposed to assist in biological membrane fusion.

scholarly journals Synaptotagmin 1 oligomerization via the juxtamembrane linker regulates spontaneous and evoked neurotransmitter release

2021 ◽  
Author(s):  
Kevin C Courtney ◽  
Yueqi Li ◽  
Jason D Vevea ◽  
Zhenyong Wu ◽  
Zhao Zhang ◽  
...  
Keyword(s):  
Electron Microscopy ◽  
Lipid Bilayers ◽  
Force Microscopy ◽  
Anionic Phospholipids ◽  
Synaptic Vesicle Exocytosis ◽  
Lysine Residues ◽  
Vesicle Exocytosis ◽  
Synaptotagmin 1 ◽  
Self Association ◽  
Aqueous Conditions

Synaptotagmin-1 (syt1) is a Ca2+ sensor that regulates synaptic vesicle exocytosis. Cell-based experiments suggest that syt1 functions as a multimer, however biochemical and electron microscopy studies have yielded contradictory findings regarding putative self-association. Here, we performed dynamic light scattering on syt1 in solution, followed by electron microscopy, and used atomic force microscopy to study syt1 self-association on supported lipid bilayers under aqueous conditions. Ring-like multimers were clearly observed. Multimerization was enhanced by Ca2+ and required anionic phospholipids. Large ring-like structures (~180 nm) were reduced to smaller rings (~30 nm) upon neutralization of a cluster of juxtamembrane lysine residues; further substitution of residues in the second C2-domain completely abolished self-association. When expressed in neurons, syt1 mutants with graded reductions in self-association activity exhibited concomitant reductions in: a) clamping spontaneous release, and b) triggering and synchronizing evoked release. Thus, the juxtamembrane linker of syt1 plays a crucial role in exocytosis by mediating multimerization.

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.

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