Calculation of Liquid-Disordered/Liquid-Ordered Line Tension from Pairwise Lipid Interactions

2020 ◽  
Vol 124 (24) ◽  
pp. 4949-4959 ◽  
Author(s):  
J. Huang ◽  
S. Hiraki ◽  
G. W. Feigenson
Keyword(s):  
Line Tension ◽  
Lipid Interactions ◽  
Liquid Ordered

scholarly journals A palmitoylation code controls PI4KIIIα complex formation and PI(4,5)P2 homeostasis at the plasma membrane

2021 ◽  
Author(s):  
Alex G Batrouni ◽  
Nirmalya Bag ◽  
Henry Phan ◽  
Barbara A Baird ◽  
Jeremy M Baskin
Keyword(s):  
Plasma Membrane ◽  
Complex Formation ◽  
Biosynthetic Pathway ◽  
Transmembrane Protein ◽  
Lipid Kinase ◽  
Lipid Interactions ◽  
Liquid Ordered ◽  
Disordered Regions

PI4KIIIα is the major enzyme responsible for generating the phosphoinositide PI(4)P at the plasma membrane. This lipid kinase forms two multicomponent complexes, both including a palmitoylated anchor, EFR3. Whereas both PI4KIIIα complexes support production of PI(4)P, the distinct functions of each complex and mechanisms underlying the interplay between them remain unknown. Here, we present roles for differential palmitoylation patterns within a tri-Cys motif in EFR3B (Cys5/Cys7/Cys8) in controlling the distribution of PI4KIIIα between these two complexes at the plasma membrane and corresponding functions in phosphoinositide homeostasis. Spacing of palmitoyl groups within three doubly palmitoylated EFR3B "lipoforms" affects both its interactions with TMEM150A, a transmembrane protein governing formation of a PI4KIIIα complex functioning in rapid PI(4,5)P2 resynthesis following PLC signaling, and its partitioning within liquid-ordered and -disordered regions of the plasma membrane. This work identifies a palmitoylation code in controlling protein-protein and protein-lipid interactions affecting a plasma membrane-resident lipid biosynthetic pathway.

Formation of modulated phases and domain rigidification in fatty acid-containing lipid membranes

2017 ◽  
Vol 19 (20) ◽  
pp. 13252-13263 ◽  
Author(s):  
Naofumi Shimokawa ◽  
Rieko Mukai ◽  
Mariko Nagata ◽  
Masahiro Takagi
Keyword(s):  
Oleic Acid ◽  
Fatty Acid ◽  
Palmitic Acid ◽  
Elaidic Acid ◽  
Lipid Membranes ◽  
Phytanic Acid ◽  
Domain Boundary ◽  
Line Tension ◽  
Modulated Phases ◽  
Liquid Ordered

A liquid-ordered domain is transformed into a solid-ordered domain by the addition of palmitic acid or elaidic acid. Oleic acid and phytanic acid reduce the line tension at the liquid domain boundary and consequently modulated phases appear.

scholarly journals Line Tension Controls Liquid-Disordered + Liquid-Ordered Domain Size Transition in Lipid Bilayers

2017 ◽  
Vol 112 (7) ◽  
pp. 1431-1443 ◽  
Author(s):  
Rebecca D. Usery ◽  
Thais A. Enoki ◽  
Sanjula P. Wickramasinghe ◽  
Michael D. Weiner ◽  
Wen-Chyan Tsai ◽  
...  
Keyword(s):  
Lipid Bilayers ◽  
Domain Size ◽  
Line Tension ◽  
Liquid Ordered

scholarly journals A palmitoylation code controls PI4KIIIα complex formation and PI(4,5)P2 homeostasis at the plasma membrane

2021 ◽  
Author(s):  
Alex G. Batrouni ◽  
Nirmalya Bag ◽  
Henry Phan ◽  
Barbara A. Baird ◽  
Jeremy M. Baskin
Keyword(s):  
Plasma Membrane ◽  
Complex Formation ◽  
Biosynthetic Pathway ◽  
Transmembrane Protein ◽  
Lipid Kinase ◽  
Lipid Interactions ◽  
Liquid Ordered ◽  
Disordered Regions

PI4KIIIα is the major enzyme responsible for generating the phosphoinositide PI(4)P at the plasma membrane. This lipid kinase forms two multicomponent complexes, both including a palmitoylated anchor, EFR3. Whereas both PI4KIIIα complexes support production of PI(4)P, the distinct functions of each complex and mechanisms underlying the interplay between them remain unknown. Here, we present roles for differential palmitoylation patterns within a tri-Cys motif in EFR3B (Cys5/Cys7/Cys8) in controlling the distribution of PI4KIIIα between these two complexes at the plasma membrane and corresponding functions in phosphoinositide homeostasis. Spacing of palmitoyl groups within three doubly palmitoylated EFR3B “lipoforms” affects both its interactions with TMEM150A, a transmembrane protein governing formation of a PI4KIIIα complex functioning in rapid PI(4,5)P2 resynthesis following PLC signaling, and its partitioning within liquid-ordered and -disordered regions of the plasma membrane. This work identifies a palmitoylation code in controlling protein-protein and protein-lipid interactions affecting a plasma membrane-resident lipid biosynthetic pathway.

scholarly journals Unroofing site-specific α-synuclein–lipid interactions at the plasma membrane

2020 ◽  
Vol 117 (32) ◽  
pp. 18977-18983 ◽  
Author(s):  
Upneet Kaur ◽  
Jennifer C. Lee
Keyword(s):  
Protein Interactions ◽  
Lifetime Distributions ◽  
Biophysical Characterization ◽  
Biologically Relevant ◽  
Lipid Interactions ◽  
C Terminus ◽  
Liquid Ordered ◽  
Lipid Environment ◽  
Lipid Protein Interactions ◽  
Synaptic Vesicle Fusion

Parkinson’s disease is associated with α-synuclein (α-syn), a cytosolic protein enriched in presynaptic terminals. The biological function of α-syn remains elusive; however, increasing evidence suggests that the protein is involved in the regulation of synaptic vesicle fusion, signifying the importance of α-syn–lipid interactions. We show that α-syn preferentially binds to GM1-rich, liquid-ordered lipid domains on cytoplasmic membranes by using unroofed cells, which encapsulates lipid complexity and cellular topology. Moreover, proteins (Rab3a, syntaxin-1A, and VAMP2) involved in exocytosis also localize with α-syn, supporting its proposed functional role in exocytosis. To investigate how these lipid/protein interactions influence α-syn at the residue level, α-syn was derivatized with an environmentally sensitive fluorophore (7-nitrobenz-2-oxa-1,3-diazol-4-yl [NBD]) at different N- and C-terminal sites. Measurements of NBD fluorescence lifetime distributions reveal that α-syn adopts a multitude of membrane-bound conformations, which were not recapitulated in simple micelle or vesicle models, indicating an exquisite sensitivity of the protein to the complex lipid environment. Interestingly, these data also suggest the participation of the C terminus in membrane localization, which is generally overlooked and thus emphasize the need to use cellularly derived and biologically relevant membranes for biophysical characterization. Collectively, our results demonstrate that α-syn is more conformationally dynamic at the membrane interface than previously appreciated, which may be important for both its physiological and pathological functions.

scholarly journals Structural Diversity of Photoswitchable Sphingolipids for Optodynamic Control of Lipid Raft Microdomains

2021 ◽  
Author(s):  
Nina Hartrampf ◽  
Samuel M. Leitao ◽  
Nils Winter ◽  
Henry Toombs-Ruane ◽  
James A. Frank ◽  
...  
Keyword(s):  
Lipid Raft ◽  
High Speed ◽  
Structural Diversity ◽  
Line Tension ◽  
Vital Role ◽  
Supported Bilayers ◽  
Liquid Ordered ◽  
Raft Domains ◽  
Lateral Localization

AbstractSphingolipids are a structurally diverse class of lipids predominantly found in the plasma membrane of eukaryotic cells. These lipids can laterally segregate with other saturated lipids and cholesterol into lipid rafts; liquid-ordered (Lo) microdomains that act as organizing centers within biomembranes. Owing the vital role of sphingolipids for lipid segregation, controlling their lateral localization is of utmost significance. Hence, we made use of the light-induced trans-cis isomerization of azobenzene-modified acyl chains, to develop a set of photoswitchable sphingolipids, with different headgroups (hydroxyl, galactosyl, phosphocholine) and backbones (sphingosine, phytosphingosine, tetrahydropyran (THP)-blocked sphingosine), able to shuttle between liquid-ordered (Lo) and liquid-disordered (Ld) regions of model membranes upon irradiation with UV-A (λ = 365 nm) and blue (λ = 470 nm) light, respectively. Using combined high-speed atomic force microscopy, fluorescence microscopy, and force spectroscopy, we investigated how these active sphingolipids laterally remodel supported bilayers upon photo-isomerization, notably in terms of domain area changes, height mismatch, line tension, and membrane piercing. Hereby, we show that all sphingosine-(Azo-β-Gal-Cer, Azo-SM, Azo-Cer) and phytosphingosine-based (Azo-α-Gal-PhCer, Azo-PhCer) photolipids behave similarly, promoting a reduction in Lo domain area when in the UV-adapted cis-isoform. In contrast, azo-sphingolipids having THP groups that block H-bonding at the sphingosine backbone (Azo-THP-SM, Azo-THP-Cer) induce an increase in the Lo domain area when in cis, accompanied by a major rise in height mismatch and line tension. These changes were fully reversible upon blue light-triggered isomerization of the various lipids back to trans, pinpointing the role of interfacial interactions for the formation of stable Lo lipid raft domains.

Test of the stability of a three-phase contact line with negative line tension

1999 ◽  
Vol 96 (9) ◽  
pp. 1335-1339 ◽  
Author(s):  
ALAN E. VAN GIESSEN, DIRK JAN BUKMAN, B.
Keyword(s):  
Contact Line ◽  
Line Tension ◽  
Phase Contact ◽  
Three Phase ◽  
The Stability
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