Transformation of Saccharomyces cerevisiae with a cDNA encoding a sterol C‐methyltransferase from Arabidopsis thaliana results in the synthesis of 24‐ethyl sterols

[摘要]

Using an EST-cDNA probe, a full-length cDNA (411) sequence of 1411 bp was isolated from A. thaliana. This sequence contained features typical of methyltransferases in general and in particular showed 38% identity with ERG6, a S. cerevisiae gene which encodes the zymosterol-C-24-methyltransferase. A yeast vector containing this ORF (4118-pYeDP60) was used to transform a wild type S. cerevisiae which accumulates predominantly ergosterol, a 24-methyl sterol as well as a mutant erg6 null mutant accumulating principally zymosterol, a sterol non-alkylated at C-24. In both cases, several 24-ethyl- and 24-ethylidene sterols were synthetized indicating that the 4118 cDNA encodes a plant sterol C-methyltransferase able to perform two sequential methylations of the sterol side chain.

[学科分类] 生物化学/生物物理

[关键词] Arabidopsis;S-Adenosylmethionine-sterol-C-methyltransferase;erg6;Complementation;I = campesterol = (24ζ)-24-methyl-cholest-5-en-3β-ol;II = sitosterol = (24R)-24-ethyl-cholest-5-en-3β-ol;III = zymosterol = 5α-cholesta-8;24-dien-3β-ol;IV = fecosterol = 5α-ergosta-8;24(241)-dien-3β-ol;V = cycloartenol =14α-trimethyl-9β;9-cyclo-5α-cholest-24-en-3β-ol;VI = 24-methylene cycloartanol = 4;4;14α-trimethyl-9β;19-cyclo-5α-ergost-24(241)-en-3β-ol;VII = 24-methylene lophenol = 4α-methyl-5α-ergosta-7;24(241)-dien-3β-ol;VII = 24-ethyliden lophenol = 4α-methyl-5α-stigmasta-7-Z-24(241)-dien-3β-ol;IX = ergosterol = ergosta-5;7;E-22-trien-3β-ol;X = Δ 7-avenasterol = 5α-stigmasta-7;Z-24(241)-dien-3β-ol;XII = stigmasta-5;7;E-22-trien-3β-ol;XIV = 5α-cholesta-7;24-dien-3β-ol;XV = cholesta-5;7;8;-tetraten-3β-ol;XVI = lanosterol = 4;4;14α-trimethyl-5α-cholesta-8;24-dien-4β-ol;XVIII = ergosta;5;7;9;E-22-tetraen-3β-ol;XVIII = eburicol =α-trimethyl-5α-egosta-8;24(241)-dien-3β-ol