cycloartenol/arabidopsis

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

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

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

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

The differences between the biosynthesis of sterols in higher plants and yeast/mammals are believed to originate at the cyclization step of oxidosqualene, which is cyclized to cycloartenol in higher plants and lanosterol in yeast/mammals. Recently, lanosterol synthase genes were identified from

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

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

Different combinations of three rate-limiting enzymes in phytosterol biosynthesis, the Arabidopsis thaliana hydroxyl methylglutaryl CoA1 (HMGR1) catalytic subunit linked to either constitutive or seed-specific β-conglycinin promoter, and the Glycine max sterol methyltransferase1 (SMT1) and sterol

In plants, the conversion of cycloartenol into functional phytosterols requires the removal of the two methyl groups at C-4 by an enzymic complex including a sterol 4alpha-methyl oxidase (SMO). We report the cloning of candidate genes for SMOs in Arabidopsis thaliana, belonging to two distinct

Higher plant cells contain a mixture of 24-desmethyl, 24-methyl(ene), and 24-ethyl(idene) sterols in given proportions according to species but also to cell type. As a first step to investigate the function of such sterol compositions in the physiology of a plant, we have illustrated in the present