Improvement of S-adenosylmethionine production by integration of the ethionine-resistance gene into chromosomes of the yeast Saccharomyces cerevisiae.

An ethionine-resistance gene cloned from Saccharomyces cerevisiae DKD-5D-H was able to enhance S-adenosyl-L-methionine (AdoMet) accumulation when it was introduced into the yeast cells on multi-copy plasmid YEp13. In order to increase the AdoMet accumulation, the gene was integrated into the yeast chromosome by using a yeast transposon Ty element. When the YEp plasmid was used for the integration, the ethionine-resistance gene was efficiently inserted into the yeast chromosomes with a substantial increase in AdoMet productivity (about twofold) in comparison with that by the yeast cells carrying the gene on an extrachromosomal multi-copy plasmid.