Showing papers on "Lanosterol published in 2007"
TL;DR: Why ergosterol is the most efficient of the three sterols at promoting the liquid-ordered phase and lipid domain formation is explained and may also furnish part of the explanation as to why cholesterol is evolutionarily preferred over lanosterol in higher-vertebrate plasma membranes.
Abstract: Lipid raft/domain formation may arise as a result of the effects of specific sterols on the physical properties of membranes. Here, using molecular dynamics simulation, we examine the effects of three closely-related sterols, ergosterol, cholesterol, and lanosterol, at a biologically relevant concentration (40 mol %) on the structural properties of a model dipalmitoyl phosphatidylcholine (DPPC) membrane at 309 and 323 K. All three sterols are found to order the DPPC acyl tails and condense the membrane relative to the DPPC liquid-phase membrane, but each one does this to a significantly different degree. The smooth alpha-face of ergosterol, together with the presence of tail unsaturation in this sterol, leads to closer interaction of ergosterol with the lipids and closer packing of the lipids with each other, so ergosterol has a higher condensing effect on the membrane, as reflected by the area per lipid. Moreover, ergosterol induces a higher proportion of trans lipid conformers, a thicker membrane, and higher lipid order parameters and is aligned more closely with the membrane normal. Ergosterol also positions itself closer to the bilayer/water interface. In contrast, the rough alpha-face of lanosterol leads to a less close interaction of the steroid ring system with the phospholipid acyl chains, and so lanosterol orders, straightens, and packs the lipid acyl chains less well and is less closely aligned with the membrane normal. Furthermore, lanosterol lies closer to the relatively disordered membrane center than do the other sterols. The behavior of cholesterol in all the above respects is intermediate between that of lanosterol and ergosterol. The findings here may explain why ergosterol is the most efficient of the three sterols at promoting the liquid-ordered phase and lipid domain formation and may also furnish part of the explanation as to why cholesterol is evolutionarily preferred over lanosterol in higher-vertebrate plasma membranes.
130 citations
TL;DR: It is reported that oxygen deprivation (hypoxia) slows demethylation of lanosterol and its metabolite 24,25-dihydrolanosterol, causing both sterols to accumulate in cells and defines a novel oxygen-sensing mechanism mediated by the combined actions of methylated intermediates in cholesterol synthesis and the hypoxia-activated transcription factor HIF-1α.
114 citations
TL;DR: In vivo findings indicate a consistent and progressive reduction in the activity of the cholesterol biosynthesis pathway in HD brain, which occurs early in these mice and generates lower levels of newly synthesized cholesterol and its intermediates, which may affect different aspects of the disease.
109 citations
TL;DR: The use of molecular genetics, molecular biology, and bioorganic chemical approaches on these mutants, as well as inhibitors of the MVA pathway, should help to understand plant sterol biosynthesis comprehensively.
Abstract: Sterols, which are biosynthesized via the cytoplasmic mevalonate (MVA) pathway, are important structural components of the plasma membrane and precursors of steroid hormones in both vertebrates and plants. Ergosterol and cholesterol are the major sterols in yeast and vertebrates, respectively. In contrast, plants produce a wide variety of phytosterols, which have various functions in plant development. Although the general biosynthetic pathway to plant sterols has been defined, the details of the biochemical, physiological, and developmental functions of genes involved in the biosynthetic network and their regulation are not well understood. Molecular genetic analyses are an effective approach to use when studying these fascinating problems. Since three enzymes, 3-hydroxy-3-methylglutaryl CoA reductase, farnesyl diphosphate synthase, and lanosterol synthase, have been functionally characterized in planta, we reviewed recent progress on these enzymes. Arabidopsis T-DNA and transposon insertion mutants are now widely available. The use of molecular genetics, molecular biology, and bioorganic chemical approaches on these mutants, as well as inhibitors of the MVA pathway, should help us to understand plant sterol biosynthesis comprehensively.
86 citations
TL;DR: It is concluded that AtSAT1 mediates phytosterol ester biosynthesis, alternative to the route previously described for phospholipid:sterol acyltransferase, and provides the molecular basis for modification of phytosterone ester level in seeds.
Abstract: Fatty acyl esters of phytosterols are a major form of sterol conjugates distributed in many parts of plants. In this study we report an Arabidopsis (Arabidopsis thaliana) gene, AtSAT1 (At3g51970), which encodes for a novel sterol O-acyltransferase. When expressed in yeast (Saccharomyces cerevisiae), AtSAT1 mediated production of sterol esters enriched with lanosterol. Enzyme property assessment using cell-free lysate of yeast expressing AtSAT1 suggested the enzyme preferred cycloartenol as acyl acceptor and saturated fatty acyl-Coenyzme A as acyl donor. Taking a transgenic approach, we showed that Arabidopsis seeds overexpressing AtSAT1 accumulated fatty acyl esters of cycloartenol, accompanied by substantial decreases in ester content of campesterol and β-sitosterol. Furthermore, fatty acid components of sterol esters from the transgenic lines were enriched with saturated and long-chain fatty acids. The enhanced AtSAT1 expression resulted in decreased level of free sterols, but the total sterol content in the transgenic seeds increased by up to 60% compared to that in wild type. We conclude that AtSAT1 mediates phytosterol ester biosynthesis, alternative to the route previously described for phospholipid:sterol acyltransferase, and provides the molecular basis for modification of phytosterol ester level in seeds.
66 citations
TL;DR: A putative operon containing homologues of essential eukaryotic sterol biosynthetic enzymes, squalene monooxygenase and oxidosqualene cyclase, has been identified in the genome of the prokaryote Methylococcus capsulatus.
Abstract: A putative operon containing homologues of essential eukaryotic sterol biosynthetic enzymes, squalene monooxygenase and oxidosqualene cyclase, has been identified in the genome of the prokaryote Methylococcus capsulatus. Expression of the squalene monooxygenase yielded a protein associated with the membrane fraction, while expression of oxidosqualene cyclase yielded a soluble protein, contrasting with the eukaryotic enzyme forms. Activity studies with purified squalene monooxygenase revealed a catalytic activity in epoxidation of 0.35 nmol oxidosqualene produced/min/nmol squalene monooxygenase, while oxidosqualene cyclase catalytic activity revealed cyclization of oxidosqualene to lanosterol with 0.6 nmol lanosterol produced/min/nmol oxidosqualene cyclase and no other products observed. The presence of prokaryotic sterol biosynthesis is still regarded as rare, and these are the first representatives of such prokaryotic enzymes to be studied, providing new insight into the evolution of sterol biosynthesis in general.
53 citations
TL;DR: Findings indicate that unlike Scap, fission yeast Scp1 responds to 4- methyl sterols and thus shares properties with mammalian HMG-CoA reductase, a sterol-sensing domain protein whose degradation is regulated by the 4-methyl sterol lanosterol.
49 citations
TL;DR: It is demonstrated that histone deacetylase 3 (HDAC3) represses the synthesis of a key regulatory enzyme and reveals a novel mechanism by which the cholesterol biosynthesis pathway can be regulated.
33 citations
TL;DR: The findings indicate that androgens may promote cholesterol biosynthesis in the meibomian gland, and this research demonstrates that testosterone stimulates a significant increase in the mRNA levels of mevalonate kinase, phosphomeValonate Kinase, and phosphomevalonates kinase.
Abstract: Purpose: We tested our hypothesis that testosterone increases the meibomian gland gene expression of numerous enzymes in the cholesterol biosynthetic pathway. Methods: Meibomian glands were obtained from castrated mice treated with vehicle or testosterone for 2 weeks. Tissues were processed for the analysis of selected mRNAs by real-time PCR. Results: Our research demonstrates that testosterone stimulates a significant increase in the mRNA levels of mevalonate kinase, phosphomevalonate kinase, mevalonate pyrophosphate decarboxylase, isopentenyl pyrophosphate isomerase, geranylgeranyl pyrophosphate synthase, squalene epoxidase, lanosterol synthase, lanosterol demethylase, and Δ 7-sterol reductase. Conclusions: Our findings indicate that androgens may promote cholesterol biosynthesis in the meibomian gland.
32 citations
TL;DR: This is the first report demonstrating the existence of the genes encoding squalene epoxidase and lanosterol synthase in prokaryotes by establishing the enzyme activities.
Abstract: Sterol biosynthesis by prokaryotic organisms is very rare. Squalene epoxidase and lanosterol synthase are prerequisite to cyclic sterol biosynthesis. These two enzymes, from the methanotrophic bacterium Methylococcus capsulatus, were functionally expressed in Escherichia coli. Structural analyses of the enzymatic products indicated that the reactions proceeded in a complete regio- and stereospecific fashion to afford (3S)-2,3-oxidosqualene from squalene and lanosterol from (3S)-2,3-oxidosqualene, in full accordance with those of eukaryotes. However, our result obtained with the putative lanosterol synthase was inconsistent with a previous report that the prokaryote accepts both (3R)- and (3S)-2,3-oxidosqualenes to afford 3-epi-lanosterol and lanosterol, respectively. This is the first report demonstrating the existence of the genes encoding squalene epoxidase and lanosterol synthase in prokaryotes by establishing the enzyme activities. The evolutionary aspect of prokaryotic squalene epoxidase and lanosterol synthase is discussed.
30 citations
Journal Article•
TL;DR: It is suggested that the sterol composition in mycelia of the fungus can be diversified by supplementing substances inhibiting enzymatic process towards the synthesis of ergosterol.
Abstract: Sterols are one of the active classes of compounds in Inonotus obliquus for their effective therapy of many diseases. In field environment, this fungus accumulates large amount of sterols. In cultured mycelia, however, this class of compounds is less accumulated. For analyzing the factors responsible for differing sterol composition, the field-grown and cultured mycelia were extracted with 80% ethanol at room temperature and total sterols were prepared using silicon gel column chromatography followed by identification using either GC-MS or spectroscopic methods. For culturing Inonotus obliquus, the seed culture was grown either in basic medium consisting of glucose (2%), yeast extract (0.5%), KH2PO4 (0.01%), MgSO4.7H20 (0.05%) and distilled water at pH 6.5, or the basic medium supplemented with serial concentrations of AgNO3. The results indicated that field-grown mycelia contained lanosterol and inotodiol (comprised 45. 47% and 25. 36% of the total sterols, respectively) and other 10 sterols (comprising the remaining 30.17%) including ergosterol biosynthetic intermediates such as 24-methylene dihydrolanosterol, 4,4-dimethylfecosterol, 4-methyl fecosterol, fecosterol and episterol. Column chromatography also led to the isolation of lanosterol, Inotodiol, trametenolic acid, foscoparianol B and a new triterpenoid foscoparianol D in field-grown mycelia. In comparison, the cultured mycelia only contained three sterols with ergosterol as the predominant one (82.20%). Lanosterol only accounted for 3.68%. Supplementing Ag+ into the culture at 0.28 micromol x L(-1) greatly enhanced content of lanosterol (accounting for 56.81%) and decreased the content of ergosterol (18.5%) together with the presence of intermediates for ergosterol biosynthesis. These results suggested that the sterol composition in mycelia of the fungus can be diversified by supplementing substances inhibiting enzymatic process towards the synthesis of ergosterol. Harsh growth conditions in field environment (i.e. temperature variation, UV irradiation etc.) can delay the synthesis of ergosterol and hereby diversify the sterol composition in the mycelia of Inonotus obliquus.
TL;DR: In vitro antifungal activities showed that some of the title compounds had higher antIFungal activity and broader antifundal spectrum than fluconazole.
TL;DR: In this article, the electrochemical reduction of the heme protein sterol-14alpha-demethylase from Mycobacterium tuberculosis (CYP51b1), or further CYP51, was investigated.
Abstract: The electrochemical reduction of the heme protein sterol-14alpha-demethylase from Mycobacterium tuberculosis (CYP51b1, or further CYP51) was investigated. Direct electron transfer was demonstrated between CYP51 and graphite screen-printed electrodes modified with gold nanoparticles and with the membrane-like synthetic surfactant didodecyl dimethylammonium bromide. The formal potential of the Fe3+/Fe2+ pair, E(1/2), is equal to -273 mV (vs. Ag/AgCl). The cathodic current corresponding to the reduction of oxygen by immobilized heme protein was registered in the presence of oxygen. Addition of lanosterol, one of the substrates of the CYP51 family, to the oxygenated solution caused a concentration-dependent increase in the reduction current in voltammetric and amperometric experiments. Ketoconazole, an inhibitor of CYP51, inhibited the catalytic cathodic current in the presence of lanosterol. Electrochemical reduction of CYP51 may serve as an adequate alternative to the reconstituted system, which requires additional redox partners for the exhibition of catalytic activity of heme proteins of the cytochrome P450 superfamily.
TL;DR: The observed affinities of the lead molecules towards CYP51 indicate that a cyclopropyl residue enhances binding to the target enzyme, which may provide some guidance for the development of novel triazole‐based antifungal lead structures.
Abstract: A series of fluconazole (1) analogues, compounds 3a-k, were prepared as potential antifungal agents. They were designed by computational docking experiments to the active site of the cytochrome P450 14alpha-sterol demethylase (CYP51), whose crystal structure is known. Preliminary biological tests showed that most of the target compounds exhibit significant activities against the eight most-common pathogenic fungi. Thereby, the most potent congener, 1-[(4-tert-butylbenzyl)(cyclopropyl)amino]-2-(2,4-difluorophenyl)-3-(1H-1,2,4-triazol-1-yl)propan-2-ol (3j), was found to exhibit a broad antifungal spectrum, being more active against Candida albicans, Candida tropicalis, Cryptococcus neoformans, Microsporum canis, and Trichophyton rubrum (MIC80 < 0.125 microg/ml) than the standard clinical drug itraconazole (2). The observed affinities of the lead molecules towards CYP51 indicate that a cyclopropyl residue enhances binding to the target enzyme. Our results may provide some guidance for the development of novel triazole-based antifungal lead structures.
TL;DR: This work has revealed a second microsomal reductase for squalene monooxygenase that is active in whole cells and leads to the accumulation of 24-dihydrolanosterol, indicating that cholesterol synthesis is blocked at lanosterol demethylase, a cytochrome P450.
TL;DR: In vitro antifungal activities showed that novel triazole compounds 10, 11, 16 and 20 exhibited strong activities against fluconazole-resistant fungi.
01 Jan 2007
TL;DR: In this paper, the active site of lanosterol 14α-demethylase was used to design and synthesize 23 propanols on the basis of the active sites of the 14α de-methylase.
Abstract: Twenty-three 1 -(1H-1,2,4-triazole-1 -y1)-2-(2,4-difluorophenyl)-3-(iV-cycloproyl-N-substituted-amino)-2-propanols were designed and synthesized on the basis of the active site of lanosterol 14α-demethylase In vitro antifungal activities showed that some of the title compounds had higher antifungal activity and broader antifungal spectrum than fluconazole
TL;DR: The chemical syntheses of ring C oxysterols for evaluation as inhibitors of sterol biosynthesis were developed, and a key intermediate in the chemical synthesis was 3β-benzoyloxy-9α, 1α-epoxy-5α-cholest-7-ene, whose structure was confirmed by X-ray crystallographic analysis and is presented herein.
Abstract: Oxygenated derivates of cholesterol and lanosterol, known as oxysterols, have consistently displayed significant activity as inhibitors of 3-hydroxy-3-methylglutaryl (HMG) CoA reductase, a key regulatory enzyme in sterol biosynthesis. We have developed the chemical syntheses of ring C oxysterols for evaluation as inhibitors of sterol biosynthesis. A key intermediate in the chemical synthesis was 3β-benzoyloxy-9α, 1α-epoxy-5α-cholest-7-ene (1), whose structure was confirmed by X-ray crystallographic analysis and is presented herein.
Patent•
22 Feb 2007
TL;DR: In this paper, the authors proposed a method for using a lanosterol synthesis enzyme originated from a plant, and provided a method to use the enzyme using a gene encoding a protein comprising one of the following amino acid sequences.
Abstract: PROBLEM TO BE SOLVED: To provide a lanosterol synthesis enzyme originated from a plant, and to provide a method for using the enzyme. SOLUTION: A gene encoding a protein comprising one of the following amino acid sequences. (1) A specific amino acid sequence; (2) an amino acid sequence comprising the specific amino acid sequence in which one to several amino acids are deleted, replaced and/or added, and having a lanosterol synthesis enzyme activity; or (3) an amino acid sequence comprising an amino acid sequence having homology of ≥70% based on the specific amino acid sequence and having a lanosterol synthesis enzyme activity. COPYRIGHT: (C)2007,JPO&INPIT
Patent•
18 Jul 2007
TL;DR: In this article, an in vitro method for screening candidate compounds for the preventive or curative treatment of acne, comprising determining the ability of a compound to modulate the expression or activity of lanosterol synthetase (LSS) and the use of modulators of this enzyme for the treatment of skin disorders associated with seborrhoea.
Abstract: The invention relates to an in vitro method for screening candidate compounds for the preventive or curative treatment of acne, comprising determining the ability of a compound to modulate the expression or activity of lanosterol synthetase (LSS) and the use of modulators of the expression or activity of this enzyme for the treatment of acne or skin disorders associated with seborrhoea. The invention also relates to methods for diagnostic or in vitro prognosis of these diseases.