[The effects of upstream region of SUC2 gene on its expression]

A series of deletions were made at upstream region of SUC2 gene with the direction from about -900 bp to the initiation codon. The DNA fragments, which contain SUC22 gene and its deleted upstream region, were inserted into multicopy plasmid. After transforming resulted plasmid into SUC strain, the invertase activities produced by the transformants were determined. Under glucose repressing condition, the glycosylated invertase produced by transformants with deletion from -636 bp to -179 bp of SUC2 gene were gradually increased. The transformants with deletion down to -223 bp and -179 bp could produce about 100 times higher glycosylated invertase activity as compared to wild type. Under glucose derepressing condition, the glycosylated invertase produced by transformants with deletion from -395 bp to -179 bp of SUC2 gene were only slightly more than that produced under glucose repressing condition. Under either glucose repressing or derepressing condition, the transformants with deletion at -89 bp and -41 bp produced only a little of glycosylated invertase, while they produced remarkably higher nonglycosylated invertase activity.