Página 1 a partir de 27 resultados
Whereas vertebrates and fungi synthesize sterols from epoxysqualene through the intermediate lanosterol, plants cyclize epoxysqualene to cycloartenol as the initial sterol. We report the cloning and characterization of CAS1, an Arabidopsis thaliana gene encoding cycloartenol synthase
Plants and certain protists use cycloeucalenol cycloisomerase (EC ) to convert pentacyclic cyclopropyl sterols to conventional tetracyclic sterols. We used a novel complementation strategy to clone a cycloeucalenol cycloisomerase cDNA. Expressing an Arabidopsis thaliana cycloartenol synthase cDNA in
The plant sterol pathway exhibits a major biosynthetic difference as compared with that of metazoans. The committed sterol precursor is the pentacyclic cycloartenol (9β,19-cyclolanost-24-en-3β-ol) and not lanosterol (lanosta-8,24-dien-3β-ol), as it was shown in the late sixties. However, plant
A random mutagenesis/in vivo selection approach was applied to generate and identify mutations that alter the product specificity of oxidosqualene-cycloartenol synthase (CAS) from Arabidopsis thaliana. This work complements previous studies of triterpene cyclase enzymes and was undertaken to provide
A cDNA clone (GgCAS1) encoding cycloartenol synthase (CAS) has been isolated from Glycyrrhiza glabra (licorice) by cross-hybridization with that of Pisum sativum CAS as a probe. The deduced amino acid sequence of GgCAS1 exhibits 89%, 83% and 81% identity to those of Pisum sativum, Panax ginseng and
The cDNA encoding cycloartenol synthase [EC 5.4.99.8] has been isolated from pea seedling by an efficient PCR using sets of degenerate primers based on the highly conserved sequences of the known 2,3-oxidosqualene cyclase cDNAs. The obtained cDNA contains a 2271-bp open reading frame and is encoding
Cycloartenol synthase converts oxidosqualene to the pentacyclic sterol precursor cycloartenol. An Arabidopsis thaliana cycloartenol synthase Ile481Val mutant was previously shown to produce lanosterol and parkeol in addition to its native product cycloartenol. Experiments are described here to
A vast array of triterpenes are found in living organisms in addition to lanosterol and cycloartenol, which are involved in sterol biosynthesis in non-photosynthetic and photosynthetic eukaryotes respectively. The chemical structure of these triterpenes is determined by a single step catalysed by
Phenotypes of Arabidopsis thaliana that carry mutations in CYCLOARTENOL SYNTHASE 1 (CAS1) which is required in sterol biosynthesis have been described. Knockout mutant alleles are responsible of a male-specific transmission defect. Plants carrying a weak mutant allele cas1-1 accumulate
A 2274 bp Arabidopsis thaliana cDNA was isolated that encodes a protein 57% identical to cycloartenol synthase from the same organism. The expressed recombinant protein encodes lupeol synthase, which converts oxidosqualene to the triterpene lupeol as the major product. Lupeol synthase is a
Cycloartenol is biosynthetically the first sterol skeleton, which is metabolized to phytosterols such as β-sitosterol and stigmasterol. β-Amyrin is the most commonly occurring aglycone skeleton for oleanane-type saponins such as glycyrrhizin and saikosaponins. It has been regarded that these cyclic
Sterols have multiple functions in all eukaryotes. In plants, sterol biosynthesis is initiated by the enzymatic conversion of 2,3-oxidosqualene to cycloartenol. This reaction is catalyzed by cycloartenol synthase 1 (CAS1), which belongs to a family of 13 2,3-oxidosqualene cyclases in Arabidopsis
Cycloartenol synthase from Arabidopsis thaliana and lanosterol synthase from Trypanosoma cruzi and Pneumocystis carinii were expressed in yeast, and their subcellular distribution in the expressing cells was compared. Determination of enzymatic (oxidosqualene cyclase, OSC) activity and SDS-PAGE
Protein degradation by the ubiquitin-26S proteasome pathway is important for the regulation of cellular processes, but the function of most F-box proteins relevant to substrate recognition is unknown. We describe the analysis of the gene Cytokinin-induced F-box encoding (CFB, AT3G44326), identified
Two methyl transfers are involved in the course of plant sterol biosynthesis and responsible for the formation of 24-alkyl sterols (mainly 24-ethyl sterols) which play major roles in plant growth and development. The first methyl transfer applies to cycloartenol, the second one to 24-methylene