scholarly journals The Many Faces of Amphipathic Helices

Biomolecules ◽  
2018 ◽  
Vol 8 (3) ◽  
pp. 45 ◽  
Author(s):  
Manuel Giménez-Andrés ◽  
Alenka Čopič ◽  
Bruno Antonny
Keyword(s):  
Lipid Bilayers ◽  
General Scheme ◽  
Membrane Curvature ◽  
Hydrophobic Residues ◽  
Cellular Processes ◽  
Amphipathic Helices ◽  
Polar Residues ◽  
Secondary Feature ◽  
Helical Turn ◽  
The Many

Amphipathic helices (AHs), a secondary feature found in many proteins, are defined by their structure and by the segregation of hydrophobic and polar residues between two faces of the helix. This segregation allows AHs to adsorb at polar–apolar interfaces such as the lipid surfaces of cellular organelles. Using various examples, we discuss here how variations within this general scheme impart membrane-interacting AHs with different interfacial properties. Among the key parameters are: (i) the size of hydrophobic residues and their density per helical turn; (ii) the nature, the charge, and the distribution of polar residues; and (iii) the length of the AH. Depending on how these parameters are tuned, AHs can deform lipid bilayers, sense membrane curvature, recognize specific lipids, coat lipid droplets, or protect membranes from stress. Via these diverse mechanisms, AHs play important roles in many cellular processes.

scholarly journals Exceptional stability of a perilipin on lipid droplets depends on its polar residues, suggesting multimeric assembly

2020 ◽  
Author(s):  
Manuel Gimenez-Andres ◽  
Tadej Emersic ◽  
Sandra Antoine-Bally ◽  
Bruno Antonny ◽  
Jure Derganc ◽  
...  
Keyword(s):  
Lipid Droplets ◽  
Protein Layer ◽  
Hydrophobic Residues ◽  
Amphipathic Helices ◽  
Polar Residues ◽  
Packing Defects ◽  
Polar Interactions ◽  
Exceptional Stability

Numerous proteins target lipid droplets (LDs) through amphipathic helices (AHs). It is generally assumed that AHs insert bulky hydrophobic residues in packing defects at the LD surface. However, this model does not explain the targeting of perilipins, the most abundant and specific amphipathic proteins of LDs. The gigantic Plin4 contains a highly repetitive AH that lacks bulky hydrophobic residues, and its LD targeting depends strongly on its length. We show that Plin4 forms a remarkably immobile protein layer at the surface of cellular or artificial LDs, making them stable over days. This Plin4 AH feature is not shared with the AHs of other perilipins, which display much faster dynamics on lipid surfaces. Plin4 AH stability on LDs is exquisitely sensitive to the nature and distribution of its polar residues. These results suggest that Plin4 forms stable arrangements of adjacent AHs via polar interactions.

scholarly journals Exceptional stability of a perilipin on lipid droplets depends on its polar residues, suggesting multimeric assembly

eLife ◽  
2021 ◽  
Vol 10 ◽  
Author(s):  
Manuel Giménez-Andrés ◽  
Tadej Emeršič ◽  
Sandra Antoine-Bally ◽  
Juan Martin D'Ambrosio ◽  
Bruno Antonny ◽  
...  
Keyword(s):  
Electrostatic Interactions ◽  
Lipid Droplets ◽  
General Mechanism ◽  
Protein Layer ◽  
Hydrophobic Residues ◽  
Amphipathic Helices ◽  
Polar Residues ◽  
Packing Defects ◽  
Exceptional Stability

Numerous proteins target lipid droplets (LDs) through amphipathic helices (AHs). It is generally assumed that AHs insert bulky hydrophobic residues in packing defects at the LD surface. However, this model does not explain the targeting of perilipins, the most abundant and specific amphipathic proteins of LDs, which are weakly hydrophobic. A striking example is Plin4, whose gigantic and repetitive AH lacks bulky hydrophobic residues. Using a range of complementary approaches, we show that Plin4 forms a remarkably immobile and stable protein layer at the surface of cellular or in vitro generated oil droplets, and decreases LD size. Plin4 AH stability on LDs is exquisitely sensitive to the nature and distribution of its polar residues. These results suggest that Plin4 forms stable arrangements of adjacent AHs via polar/electrostatic interactions, reminiscent of the organization of apolipoproteins in lipoprotein particles, thus pointing to a general mechanism of AH stabilization via lateral interactions.

Spotting Differences in Molecular Dynamic Simulations of Influenza A M2 Protein-Ligand Complexes by Varying M2 construct, Lipid Bilayer and Force Field

2019 ◽  
Author(s):  
Dimitrios Kolokouris ◽  
Iris Kalenderoglou ◽  
Panagiotis Lagarias ◽  
Antonios Kolocouris
Keyword(s):  
Molecular Dynamic ◽  
Lipid Bilayer ◽  
Influenza A ◽  
Md Simulations ◽  
Membrane Curvature ◽  
Buffer Size ◽  
M2 Protein ◽  
Dynamic Simulations ◽  
Amphipathic Helices ◽  
Drug Protein Binding

<p>We studied by molecular dynamic (MD) simulations systems including the inward<sub>closed</sub> state of influenza A M2 protein in complex with aminoadamantane drugs in membrane bilayers. We varied the M2 construct and performed MD simulations in M2TM or M2TM with amphipathic helices (M2AH). We also varied the lipid bilayer by changing either the lipid, DMPC or POPC, POPE or POPC/cholesterol (chol), or the lipids buffer size, 10x10 Å<sup>2 </sup>or 20x20 Å<sup>2</sup>. We aimed to suggest optimal system conditions for the computational description of this ion channel and related systems. Measures performed include quantities that are available experimentally and include: (a) the position of ligand, waters and chlorine anion inside the M2 pore, (b) the passage of waters from the outward Val27 gate of M2 S31N in complex with an aminoadamantane-aryl head blocker, (c) M2 orientation, (d) the AHs conformation and structure which is affected from interactions with lipids and chol and is important for membrane curvature and virus budding. In several cases we tested OPLS2005, which is routinely applied to describe drug-protein binding, and CHARMM36 which describes reliably protein conformation. We found that for the description of the ligands position inside the M2 pore, a 10x10 Å<sup>2</sup> lipids buffer in DMPC is needed when M2TM is used but 20x20 Å<sup>2</sup> lipids buffer of the softer POPC; when M2AH is used all 10x10 Å<sup>2</sup> lipid buffers with any of the tested lipids can be used. For the passage of waters at least M2AH with a 10x10 Å<sup>2</sup> lipid buffer is needed. The folding conformation of AHs which is defined from hydrogen bonding interactions with the bilayer and the complex with chol is described well with a 10x10 Å<sup>2</sup> lipids buffer and CHARMM36. </p>

scholarly journals Cardiolipin-Containing Lipid Membranes Attract the Bacterial Cell Division Protein DivIVA

2021 ◽  
Vol 22 (15) ◽  
pp. 8350
Author(s):  
Naďa Labajová ◽  
Natalia Baranova ◽  
Miroslav Jurásek ◽  
Robert Vácha ◽  
Martin Loose ◽  
...  
Keyword(s):  
Cell Division ◽  
Lipid Bilayers ◽  
Bacterial Cell ◽  
Lipid Membranes ◽  
Model Organism ◽  
Active Role ◽  
Membrane Curvature ◽  
Bacterial Cell Division ◽  
Division Site ◽  
Clostridioides Difficile

DivIVA is a protein initially identified as a spatial regulator of cell division in the model organism Bacillus subtilis, but its homologues are present in many other Gram-positive bacteria, including Clostridia species. Besides its role as topological regulator of the Min system during bacterial cell division, DivIVA is involved in chromosome segregation during sporulation, genetic competence, and cell wall synthesis. DivIVA localizes to regions of high membrane curvature, such as the cell poles and cell division site, where it recruits distinct binding partners. Previously, it was suggested that negative curvature sensing is the main mechanism by which DivIVA binds to these specific regions. Here, we show that Clostridioides difficile DivIVA binds preferably to membranes containing negatively charged phospholipids, especially cardiolipin. Strikingly, we observed that upon binding, DivIVA modifies the lipid distribution and induces changes to lipid bilayers containing cardiolipin. Our observations indicate that DivIVA might play a more complex and so far unknown active role during the formation of the cell division septal membrane.

scholarly journals The Amazing Acrobat: Yeast’s Histone H3K56 Juggles Several Important Roles While Maintaining Perfect Balance

Genes ◽  
2021 ◽  
Vol 12 (3) ◽  
pp. 342
Author(s):  
Lihi Gershon ◽  
Martin Kupiec
Keyword(s):  
Dna Replication ◽  
Genome Stability ◽  
Entry And Exit ◽  
Yeast Saccharomyces Cerevisiae ◽  
Cellular Processes ◽  
M Phase ◽  
Dna Replication And Repair ◽  
H3k56 Acetylation ◽  
Timely Fashion ◽  
The Many

Acetylation on lysine 56 of histone H3 of the yeast Saccharomyces cerevisiae has been implicated in many cellular processes that affect genome stability. Despite being the object of much research, the complete scope of the roles played by K56 acetylation is not fully understood even today. The acetylation is put in place at the S-phase of the cell cycle, in order to flag newly synthesized histones that are incorporated during DNA replication. The signal is removed by two redundant deacetylases, Hst3 and Hst4, at the entry to G2/M phase. Its crucial location, at the entry and exit points of the DNA into and out of the nucleosome, makes this a central modification, and dictates that if acetylation and deacetylation are not well concerted and executed in a timely fashion, severe genomic instability arises. In this review, we explore the wealth of information available on the many roles played by H3K56 acetylation and the deacetylases Hst3 and Hst4 in DNA replication and repair.

scholarly journals Interphotoreceptor coupling: an evolutionary perspective

2021 ◽  
Author(s):  
Lorenzo Cangiano ◽  
Sabrina Asteriti
Keyword(s):  
Visual Information ◽  
Signal To Noise Ratio ◽  
Electrical Coupling ◽  
Physiological Role ◽  
Cellular Processes ◽  
Contact Points ◽  
Highly Sensitive ◽  
The Many ◽  
The Impact

AbstractIn the vertebrate retina, signals generated by cones of different spectral preference and by highly sensitive rod photoreceptors interact at various levels to extract salient visual information. The first opportunity for such interaction is offered by electrical coupling of the photoreceptors themselves, which is mediated by gap junctions located at the contact points of specialised cellular processes: synaptic terminals, telodendria and radial fins. Here, we examine the evolutionary pressures for and against interphotoreceptor coupling, which are likely to have shaped how coupling is deployed in different species. The impact of coupling on signal to noise ratio, spatial acuity, contrast sensitivity, absolute and increment threshold, retinal signal flow and colour discrimination is discussed while emphasising available data from a variety of vertebrate models spanning from lampreys to primates. We highlight the many gaps in our knowledge, persisting discrepancies in the literature, as well as some major unanswered questions on the actual extent and physiological role of cone-cone, rod-cone and rod-rod communication. Lastly, we point toward limited but intriguing evidence suggestive of the ancestral form of coupling among ciliary photoreceptors.

scholarly journals Membrane Curvature Sensing by Amphipathic Helices

2011 ◽  
Vol 286 (49) ◽  
pp. 42603-42614 ◽  
Author(s):  
Martin Borch Jensen ◽  
Vikram Kjøller Bhatia ◽  
Christine C. Jao ◽  
Jakob Ewald Rasmussen ◽  
Søren L. Pedersen ◽  
...  
Keyword(s):  
Membrane Curvature ◽  
Curvature Sensing ◽  
Amphipathic Helices

scholarly journals Roles of Amphipathic Helices and the Bin/Amphiphysin/Rvs (BAR) Domain of Endophilin in Membrane Curvature Generation

2010 ◽  
Vol 285 (26) ◽  
pp. 20164-20170 ◽  
Author(s):  
Christine C. Jao ◽  
Balachandra G. Hegde ◽  
Jennifer L. Gallop ◽  
Prabhavati B. Hegde ◽  
Harvey T. McMahon ◽  
...  
Keyword(s):  
Membrane Curvature ◽  
Bar Domain ◽  
Amphipathic Helices
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