Novel saccharomyces cerevisiae expression system and construction method thereof

A Saccharomyces cerevisiae expression system consisting of a host transfected by an expression vector, wherein the expression vector is circular and is a shuttle plasmid vector constructed between Saccharomyces cerevisiae and Escherichia coli, and the expession vector comprises a plurality of operable elements, the plurality of operable elements comprising sequentially from 5′ to 3′ a YEplac195 plasmid backbone, an exogenous or endogenous gene expression cassette, and a selective marker gene expression cassette;

• wherein the YEplac195 plasmid is a yeast episomal plasmid including an ori of a yeast 2μ plasmid;
• wherein the exogenous or endogenous gene expression cassette comprises sequentially from upstream to downstream:
• an rDNA promoter, an internal ribosome entry site sequence, an exogenous or endogenous gene expression cassette, a poly(T) sequence, and an rDNA terminator;
• and
• wherein the selective marker gene expression cassette comprises a promoter, a selective marker gene, and a transcription terminator.