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Université de Fribourg

Accumulation of long-chain bases in yeast promotes their conversion to a long-chain base vinyl ether

Martínez-Montañés, Fernando ; Lone, Museer A. ; Hsu, Fong-Fu ; Schneiter, Roger

In: Journal of Lipid Research, 2016, vol. 57, no. 11, p. 2040–2050

Long-chain bases (LCBs) are the precursors to ceramide and sphingolipids in eukaryotic cells. They are formed by the action of serine palmitoyl-CoA transferase (SPT), a complex of integral membrane proteins located in the endoplasmic reticulum. SPT activity is negatively regulated by Orm proteins to prevent the toxic overaccumulation of LCBs. Here we show that overaccumulation of LCBs in...

Université de Fribourg

An acetylation/deacetylation cycle controls the export of sterols and steroids from S. cerevisiae

Tiwari, Rashi ; Köffel, René ; Schneiter, Roger

In: The EMBO Journal, 2007, vol. 26, no. 24, p. 5109–5119

Sterol homeostasis in eukaryotic cells relies on the reciprocal interconversion of free sterols and steryl esters. Here we report the identification of a novel reversible sterol modification in yeast, the sterol acetylation/deacetylation cycle. Sterol acetylation requires the acetyltransferase ATF2, whereas deacetylation requires SAY1, a membrane-anchored deacetylase with a putative active site...

Université de Fribourg

Acyl-CoA-binding protein, Acb1p, is required for normal vacuole function and ceramide synthesis in Saccharomyces cerevisiae

Faergeman, Nils J. ; Feddersen, Søren ; Christiansen, Janne K. ; Larsen, Morten K. ; Schneiter, Roger ; Ungermann, Christian ; Mutenda, Kudzai ; Roepstroff, Peter ; Knudsen, Jens

In: Biochemical Journal, 2004, vol. 380, p. 907-918

In the present study, we show that depletion of acyl-CoA-binding protein, Acb1p, in yeast affects ceramide levels, protein trafficking, vacuole fusion and structure. Vacuoles in Acb1p-depleted cells are multi-lobed, contain significantly less of the SNAREs (soluble N-ethylmaleimide-sensitive fusion protein attachment protein receptors) Nyv1p, Vam3p and Vti1p, and are unable to fuse in vitro. Mass...

Université de Fribourg

Architecture of lipid droplets in endoplasmic reticulum is determined by phospholipid intrinsic curvature

Choudhary, Vineet ; Golani, Gonen ; Joshi, Amit S. ; Cottier, Stéphanie ; Schneiter, Roger ; Prinz, William A. ; Kozlov, Michael M.

In: Current Biology, 2018, vol. 28, no. 6, p. 915-926.e9

Lipid droplets (LDs) store fats and play critical roles in lipid and energy homeostasis. They form between the leaflets of the endoplasmic reticulum (ER) membrane and consist of a neutral lipid core wrapped in a phospholipid monolayer with proteins. Two types of ER-LD architecture are thought to exist and be essential for LD functioning. Maturing LDs either emerge from the ER into the...

Université de Fribourg

The CAP protein superfamily: function in sterol export and fungal virulence

Schneiter, Roger ; Pietro, Antonio Di

In: BioMolecular Concepts, 2013, vol. 4, no. 5, p. 519-525

CAP superfamily proteins, also known as sperm-coating proteins, are found in all kingdoms of life and have been implicated in a variety of physiological contexts, including immune defense in plants and mammals, sperm maturation and fertilization, fungal virulence, and toxicity of insect and reptile venoms as well as prostate and brain cancer. CAP family members are mostly secreted...

Université de Fribourg

The caveolin-binding motif of the pathogen-related yeast protein Pry1, a member of the CAP protein superfamily, is required for in vivo export of cholesteryl acetate

Choudhary, Vineet ; Darwiche, Rabih ; Gfeller, David ; Zoete, Vincent ; Michielin, Olivier ; Schneiter, Roger

In: Journal of Lipid Research, 2014, vol. 55, no. 5, p. 883-894

Proteins belonging to the CAP superfamily are present in all kingdoms of life and have been implicated in different physiological processes. Their molecular mode of action, however, is poorly understood. Saccharomyces cerevisiae expresses three members of this superfamily, pathogen-related yeast (Pry)1, -2, and -3. We have recently shown that Pry function is required for the secretion of...

Université de Fribourg

The Cdc42 effectors ste20, Cla4, and Skm1 down-regulate the expression of genes involved in sterol uptake by a mitogen-activated protein kinase-independent pathway

Lin, Meng ; Unden, Heike ; Jacquier, Nicolas ; Schneiter, Roger ; Just, Ursula ; Höfken, Thomas

In: Molecular Biology of the Cell, 2009, vol. 20, no. 22, p. 4826-4837

In Saccharomyces cerevisiae, the Rho-type GTPase Cdc42 regulates polarized growth through its effectors, including the p21-activated kinases (PAKs) Ste20, Cla4, and Skm1. Previously, we demonstrated that Ste20 interacts with several proteins involved in sterol synthesis that are crucial for cell polarization. Under anaerobic conditions, sterols cannot be synthesized and need to be imported into...

Université de Fribourg

Chemical crosslinking and mass spectrometry to elucidate the topology of integral membrane proteins

Debelyy, Mykhaylo O. ; Waridel, Patrice ; Quadroni, Manfredo ; Schneiter, Roger ; Conzelmann, Andreas

In: PLOS ONE, 2017, vol. 12, no. 10, p. e0186840

Here we made an attempt to obtain partial structural information on the topology of multispan integral membrane proteins of yeast by isolating organellar membranes, removing peripheral membrane proteins at pH 11.5 and introducing chemical crosslinks between vicinal amino acids either using homo- or hetero-bifunctional crosslinkers. Proteins were digested with specific proteases and the...

Université de Fribourg

Chemogenetic E-MAP in Saccharomyces cerevisiae for identification of membrane transporters operating lipid flip flop

Vazquez, Hector M. ; Vionnet, Christine ; Roubaty, Carole ; Mallela, Shamroop k. ; Schneiter, Roger ; Conzelmann, Andreas

In: PLOS Genet, 2016, vol. 12, no. 7, p. e1006160

While most yeast enzymes for the biosynthesis of glycerophospholipids, sphingolipids and ergosterol are known, genes for several postulated transporters allowing the flopping of biosynthetic intermediates and newly made lipids from the cytosolic to the lumenal side of the membrane are still not identified. An E-MAP measuring the growth of 142'108 double mutants generated by systematically...