Cloning and expression of xylitol dehydrogenase gene from Candida shehatae in Saccharomyces cerevisiae

摘要

The inability of Saccharomyces cerevisiae to utilize xylose is attributed to its inability to convertxylose to xylulose. Low xylose reductase and xylitol dehydrogenase activities in S. cerevisiae are regarded as thereason of blocking the pathway from xylose to xylulose. In previous study, we cloned and expressed the xylosereductase gene from Candida shehatae in S. cerevisiae which enables it to grow in xylose-containing medium. Inthis study, we investigated the activity of xylitol dehydrogenase gene of C. shehatae in S. cerevisiae. The xylitoldehydrogenase gene (XYL2) from C. shehatae was amplified by polymerase chain reaction (PCR). It was placedinto plasmid pSFAU to produce the recombinant expression vector pSFAU-XDH. Subsequently, the pSFAU-XDHvector was transformed into S. cerevisiae TISTR5339 to produce a recombinant S. cerevisiae TISTR5339-XDH.The recombinant S. cerevisiae showed higher growth rate than the untransformed strain in media containing xylitolas a carbon source. The specific enzyme activity of xylitol dehydrogenase in the recombinant S. cerevisiae wasdetermined. The highest specific activity was 0.805 mU mg-1 protein or 0.013 nkat mg-1. This work demonstratesthe functionality of the gene xylitol dehydrogenase from C. shehatae in S. cerevisiae.