Yeast perilipin Pet10p/Pln1p interacts with Erg6p in ergosterol metabolism.

Lipid droplets (LD) are highly dynamic organelles specialized for the regulation of energy storage and cellular homeostasis. LD consist of a neutral lipid core surrounded by a phospholipid monolayer membrane with embedded proteins, most of which are involved in lipid homeostasis. In this study, we focused on one of the major LD proteins, sterol C24-methyltransferase, encoded by ERG6.

Metabolism of Storage Lipids and the Role of Lipid Droplets in the Yeast Schizosaccharomyces pombe.

Storage lipids, triacylglycerols (TAG), and steryl esters (SE), are predominant constituents of lipid droplets (LD) in fungi. In several yeast species, metabolism of TAG and SE is linked to various cellular processes, including cell division, sporulation, apoptosis, response to stress, and lipotoxicity. In addition, TAG are an important source for the generation of value-added lipids for industrial and biomedical applications.

Mutations in the nucleotide-binding domain of putative sterol importers Aus1 and Pdr11 selectively affect utilization of exogenous sterol species in yeast.

Sterol uptake in the yeast Saccharomyces cerevisiae is mediated by two plasma membrane ATP-binding cassette transporters, Aus1 and Pdr11. Their expression is regulated by oxygen and is triggered by anaerobic growth conditions. Under these conditions, internal ergosterol synthesis is arrested and utilization of exogenous sterol is vital for yeast cells.

Squalene lipotoxicity in a lipid droplet-less yeast mutant is linked to plasma membrane dysfunction.

Squalene is a naturally occurring triterpene with wide industrial applications. Due to limited natural resources, production of this valuable lipid in yeast is of high commercial relevance. Typically low levels of squalene in yeast can be significantly increased by specific cultivation conditions or genetic modifications.

The complete mitochondrial DNA sequence from Kazachstania sinensis reveals a general +1C frameshift mechanism in CTGY codons.

The complete mitochondrial DNA (mtDNA) sequence from Kazachstania sinensis was analysed and compared to mtDNA from related yeasts. It contained the same set of genes; however, it only contained 23 tRNAs, as the trnR2 gene was absent. Most of the 12 introns within cox1, cob and rnl genes were inserted in the same sites as in other yeasts; however, two introns in rnl were in unusual positions.

Biosynthetic Approaches to Squalene Production: The Case of Yeast.

Squalene is a precursor in the eukaryotic sterol biosynthesis. It is a valuable compound with several human health-related applications. Since the traditional natural resources of squalene are limited, alternatives for the production of squalene on industrial scale have been intensively explored during past years.

Squalene is lipotoxic to yeast cells defective in lipid droplet biogenesis.

The toxic effect of overloaded lipids on cell physiology and viability was described in various organisms. In this study we focused on the potential lipotoxicity of squalene, a linear triterpene synthesized in eukaryotic cells as an intermediate in sterol biosynthesis. Squalene toxicity was studied in the yeast Saccharomyces cerevisiae, a model unicellular eukaryote established in lipotoxicity studies.

Baker's Yeast Deficient in Storage Lipid Synthesis Uses cis-Vaccenic Acid to Reduce Unsaturated Fatty Acid Toxicity.

The role of cis-vaccenic acid (18:1n-7) in the reduction of unsaturated fatty acids toxicity was investigated in baker's yeast Saccharomyces cerevisiae. The quadruple mutant (QM, dga1Δ lro1Δ are1Δ are2Δ) deficient in enzymes responsible for triacylglycerol and steryl ester synthesis has been previously shown to be highly sensitive to exogenous unsaturated fatty acids. We have found that cis-vaccenic acid accumulated during cultivation in the QM cells but not in the corresponding wild type strain.

Production of squalene by lactose-fermenting yeast Kluyveromyces lactis with reduced squalene epoxidase activity.

Unlabelled: Utilization of yeast as squalene source for commercial use is limited by relatively high production costs. The ability of Kluyveromyces lactis to grow on cheap lactose-containing diary industry wastes could improve the economy of the production process. We therefore tested the potential of this yeast for squalene production.

Squalene epoxidase as a target for manipulation of squalene levels in the yeast Saccharomyces cerevisiae.

Squalene is a valuable natural substance with several biotechnological applications. In the yeast Saccharomyces cerevisiae, it is produced in the isoprenoid pathway as the first precursor dedicated to ergosterol biosynthesis. The aim of this study was to explore the potential of squalene epoxidase encoded by the ERG1 gene as the target for manipulating squalene levels in yeast.

The yeast Saccharomyces cerevisiae Pdr16p restricts changes in ergosterol biosynthesis caused by the presence of azole antifungals.

Pdr16p belongs to the family of phosphatidylinositol transfer proteins in yeast. The absence of Pdr16p results in enhanced susceptibility to azole antifungals in Saccharomyces cerevisiae. In the major fungal human pathogen Candida albicans, CaPDR16 is a contributing factor to clinical azole resistance.

Effect of cellular cholesterol changes on insulin secretion by tumor cell lines.

Unlabelled: Glucose and cell swelling induce insulin secretion by alternative signaling pathways. Swelling-induced secretion is in most systems independent of calcium and various mediators of glucose stimulation. Comparison of two insulinoma tumor cell lines revealed surprising difference; INS-1E cells in contrast to INS-1 cells and isolated rat pancreatic islets do not respond to hypotonicity in the presence of calcium.

Is fat so bad? Modulation of endoplasmic reticulum stress by lipid droplet formation.

LDs (lipid droplets) have long been considered as inert particles used by the cells to store fatty acids and sterols as esterified non-toxic lipid species (i.e. triacylglycerols and steryl esters).

Effects of 3-hydroxy-3-methylglutaryl-coenzyme a reductase inhibitor pravastatin on membrane lipids and membrane associated functions of Methanothermobacter thermautotrophicus.

The role of archaeal membrane and its lipid constituents was investigated in bioenergetic functions of Methanothermobacter thermautotrophicus. The effects were determined of the 3-hydroxy-3-methylglutaryl-coenzyme A reductase inhibitor, pravastatin, on lipid composition, and its impact on some bioenergetic functions of treated cells. Pravastatin remarkably inhibited the growth of M.

Chemogenomic and transcriptome analysis identifies mode of action of the chemosensitizing agent CTBT (7-chlorotetrazolo[5,1-c]benzo[1,2,4]triazine).

Background: CTBT (7-chlorotetrazolo [5,1-c]benzo[1,2,4]triazine) increases efficacy of commonly used antifungal agents by an unknown mechanism. It increases the susceptibility of Saccharomyces cerevisiae, Candida albicans and Candida glabrata cells to cycloheximide, 5-fluorocytosine and azole antimycotic drugs. Here we elucidate CTBT mode of action with a combination of systematic genetic and transcriptome analysis.

Effect of lipid particle biogenesis on the subcellular distribution of squalene in the yeast Saccharomyces cerevisiae.

Squalene belongs to the group of isoprenoids and is a precursor for the synthesis of sterols, steroids, and ubiquinones. In the yeast Saccharomyces cerevisiae, the amount of squalene can be increased by variation of growth conditions or by genetic manipulation. In this report, we show that a hem1Delta mutant accumulated a large amount of squalene, which was stored almost exclusively in cytoplasmic lipid particles/droplets.

Tributyltin-resistant Methanothermobacter thermautotrophicus mutant with mutational substitutions in the A1A0-ATP synthase operon.

A spontaneous mutant of Methanothermobacter thermautotrophicus resistant to tributyltin chloride (TBT) was isolated. TBT, the inhibitor of the A(0) domain of A(1)A(0)-ATP synthase, inhibits methanogenesis in the wild-type cells; however, the TBT-resistant mutant exhibited methanogenesis even in the presence of 800 microM TBT. ATP synthesis driven by methanogenic electron transport was markedly diminished in the mutant strain.

Hypergravity-induced increase in plasma catecholamine and corticosterone levels in telemetrically collected blood of rats during centrifugation.

Rats subjected to various accelerations (+G) exhibited increased levels of plasma epinephrine (EPI), norepinephrine (NE), and corticosterone. However, the collection of blood was performed after a centrifugation finished, and therefore the levels could be affected by the process of deceleration. The aim of this study was to evaluate plasma EPI, NE, and corticosterone levels in blood collected directly during centrifugation after reaching different G (2-6), using newly developed remote-controlled equipment.

Control of lipid accumulation in the yeast Yarrowia lipolytica.

A genomic comparison of Yarrowia lipolytica and Saccharomyces cerevisiae indicates that the metabolism of Y. lipolytica is oriented toward the glycerol pathway. To redirect carbon flux toward lipid synthesis, the GUT2 gene, which codes for the glycerol-3-phosphate dehydrogenase isomer, was deleted in Y.

Chemosensitisation of drug-resistant and drug-sensitive yeast cells to antifungals.

Multidrug resistance in yeast results from overexpression of genes encoding drug efflux transporters owing to gain-of-function mutations in transcription factors regulating their expression. We have screened a library of synthetic compounds for modulators of drug resistance using the multidrug-resistant Saccharomyces cerevisiae pdr3-9 mutant strain. One of the compounds, 7-chlorotetrazolo[5,1-c]benzo[1,2,4]triazine (CTBT), displayed weak antifungal activity and strongly inhibited the growth of yeast cells in combination with subinhibitory concentrations of other antifungals with a different mode of action.

Characterization of squalene epoxidase of Saccharomyces cerevisiae by applying terbinafine-sensitive variants.

Squalene epoxidase (SE) is the target of terbinafine, which specifically inhibits the fungal enzyme in a noncompetitive manner. On the basis of functional homologies to p-hydroxybenzoate hydroxylase (PHBH) from Pseudomonas fluorescens, the Erg1 protein contains two flavin adenine dinucleotide (FAD) domains and one nucleotide binding (NB) site. By in vitro mutagenesis of the ERG1 gene, which codes for the Saccharomyces cerevisiae SE, we isolated erg1 alleles that conferred increased terbinafine sensitivity or that showed a lethal phenotype when they were expressed in erg1-knockout strain KLN1.

Two mutants selectively resistant to polyenes reveal distinct mechanisms of antifungal activity by nystatin and amphotericin B.

Polyene macrolides nystatin and amphotericin B are widely used in the treatment of fungal infections. In order to characterize factors affecting polyene activity, we have isolated Saccharomyces cerevisiae mutants showing selective resistance to nystatin and amphotericin B. Characterization of two of these mutants (nystatin-resistant mutant X1/16 and amphotericin B-resistant mutant X3/33) is presented.