Université de Fribourg

Accurate estimation of membrane capacitance from atomistic molecular dynamics simulations of zwitterionic lipid bilayers

Ardham, Vikram Reddy ; Zoni, Valeria ; Adamowicz, Sylvain ; Campomanes, Pablo ; Vanni, Stefano

In: The Journal of Physical Chemistry B, 2020, vol. 124, no. 38, p. 8278–8286

Lipid membranes are indispensable to life, and they regulate countless cellular processes. To investigate the properties of membranes under controlled conditions, numerous reconstitution methods have been developed over the last few decades. Several of these methods result in the formation of lipid bilayers containing residual hydrophobic molecules between the two monolayers. These...

Université de Fribourg

An atomistic look into bio-inspired nanoparticles and their molecular interactions with cells

Petretto, Emanuele ; Campomanes, Pablo ; Stellacci, Francesco ; Rothen-Rutishauser, Barbara ; Petri-Fink, Alke ; Vanni, Stefano

In: CHIMIA International Journal for Chemistry, 2019, vol. 73, no. 1, p. 78–80

Nanoparticles (NPs) have sizes that approach those of pathogens and they can interact with the membranes of eukaryotic cells in an analogous fashion. Typically, NPs are taken up by the cell via the plasma membrane by receptor-mediated processes and subsequently interact with various endomembranes. Unlike pathogens, however, NPs lack the remarkable specificity gained during the evolutionary...

Université de Fribourg

Conserved functions of ether lipids and sphingolipids in the early secretory pathway

Jiménez-Rojo, Noemi ; Leonetti, Manuel D. ; Zoni, Valeria ; Colom, Adai ; Feng, Suihan ; Iyengar, Namrata R. ; Matile, Stefan ; Roux, Aurélien ; Vanni, Stefano ; Weissman, Jonathan S. ; Riezman, Howard

In: Current Biology, 2020, vol. 30, no. 19, p. 3775-3787.e7

Sphingolipids play important roles in physiology and cell biology, but a systematic examination of their functions is lacking. We performed a genome-wide CRISPRi screen in sphingolipid-depleted human cells and identified hypersensitive mutants in genes of membrane trafficking and lipid biosynthesis, including ether lipid synthesis. Systematic lipidomic analysis showed a coordinate regulation...

Université de Fribourg

ER membrane phospholipids and surface tension control cellular lipid droplet formation

M'barek, Kalthoum Ben ; Ajjaji, Dalila ; Chorlay, Aymeric ; Vanni, Stefano ; Forêt, Lionel ; Thiam, Abdou Rachid

In: Developmental Cell, 2017, vol. 41, no. 6, p. 591–604.e7

Cells convert excess energy into neutral lipids that are made in the endoplasmic reticulum (ER) bilayer. The lipids are then packaged into spherical or budded lipid droplets (LDs) covered by a phospholipid monolayer containing proteins. LDs play a key role in cellular energy metabolism and homeostasis. A key unanswered question in the life of LDs is how they bud off from the ER. Here, we...

Université de Fribourg

Estimating the accuracy of the MARTINI model towards the investigation of Peripheral Protein-Membrane Interactions

Srinivasan, Sriraksha ; Zoni, Valeria ; Vanni, Stefano

In: Faraday Discussions, 2020, p. -

Peripheral membrane proteins play a major role in numerous biological processes by transiently associating with cellular membranes, often with extreme membrane specificity. Because of the short-lived nature of these interactions, molecular dynamics (MD) simulations have emerged as an appealing tool to characterize at the structural level the molecular details of the protein-membrane...

Université de Fribourg

From zero to six double bonds: phospholipid unsaturation and organelle function

Antonny, Bruno ; Vanni, Stefano ; Shindou, Hideo ; Thierry, Ferreira

In: Trends in Cell Biology, 2015, vol. 25, no. 7, p. 427–436

Cellular phospholipids (PLs) differ by the nature of their polar heads as well as by the length and unsaturation level of their fatty acyl chains. We discuss how the ratio between saturated, monounsaturated, and polyunsaturated PLs impacts on the functions of such organelles as the endoplasmic reticulum, synaptic vesicles, and photoreceptor discs. Recent experiments and simulations suggest...

Université de Fribourg

How do ethanolamine plasmalogens contribute to order and structure of neurological membranes?

West, Ana ; Zoni, Valeria ; Teague, Walter E. ; Leonard, Alison N. ; Vanni, Stefano ; Gawrisch, Klaus ; Tristram-Nagle, Stephanie ; Sachs, Jonathan N. ; Klauda, Jeffery B.

In: The Journal of Physical Chemistry B, 2020, vol. 124, no. 5, p. 828–839

Ethanolamine plasmalogen (EtnPLA) is a conical-shaped ether lipid and an essential component of neurological membranes. Low stability against oxidation limits its study in experiments. The concentration of EtnPLA in the bilayer varies depending on cell type and disease progression. Here we report on mixed bilayers of 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine (POPC) and 1-(1Z-...

Université de Fribourg

Local accumulation of diacylglycerol alters membrane properties nonlinearly due to its transbilayer activity

Campomanes, Pablo ; Zoni, Valeria ; Vanni, Stefano

In: Communications Chemistry, 2019, vol. 2, no. 1, p. 72

Diacylglycerols (DAGs) are bioactive lipids that are ubiquitously present at low concentrations in cellular membranes. Upon the activation of lipid remodeling enzymes such as phospholipase C and phosphatidic acid phosphatase, DAG concentration increases, leading to a disruption of the lamellar phase of lipid membranes. To investigate the structural origin of these phenomena, here we develop ...

Université de Fribourg

Methyl-branched lipids promote the membrane adsorption of α-synuclein by enhancing shallow lipid-packing defects

Garten, Matthias ; Prévost, Coline ; Cadart, Clotilde ; Gautier, Romain ; Bousset, Luc ; Melki, Ronald ; Bassereau, Patricia ; Vanni, Stefano

In: Physical Chemistry Chemical Physics, 2015, vol. 17, no. 24, p. 15589–15597

Alpha-synuclein (AS) is a synaptic protein that is directly involved in Parkinson's disease due to its tendency to form protein aggregates. Since AS aggregation can be dependent on the interactions between the protein and the cell plasma membrane, elucidating the membrane binding properties of AS is of crucial importance to establish the molecular basis of AS aggregation into toxic fibrils....

Université de Fribourg

Packmem: a versatile tool to compute and visualize interfacial packing defects in lipid bilayers

Gautier, Romain ; Bacle, Amélie ; Tiberti, Marion L. ; Fuchs, Patrick F. ; Vanni, Stefano ; Antonny, Bruno

In: Biophysical Journal, 2018, vol. 115, no. 3, p. 436–444

The analysis of the structural organization of lipid bilayers is generally performed across the direction normal to the bilayer/water interface, whereas the surface properties of the bilayer at the interface with water are often neglected. Here, we present PackMem, a bioinformatic tool that performs a topographic analysis of the bilayer surface from various molecular dynamics simulations....