Role of saccharomyces cerevisiae oxidoreductases Bdhlp and Aralp in the metabolism of acetoin and 2,3-butanediol

NAD-dependent butanediol dehydrogenase (Bdh1p) from Saccharomyces cerevisiae reversibly transforms acetoin to 2,3-butanediol in a stereospecific manner. Deletion of BDH1 resulted in an accumulation of acetoin and a diminution of 2,3-butanediol in two 5. cerevisiae strains under two different growth conditions. The concentrations of (2R,3R)-2,3- butanediol are mostly dependent on Bdhlp activity, while those of (meso)-2,3butanediol are also influenced by the activity of NADP(H)-dependent oxidoreductases. One of them has been purified and shown to be D-arabinose dehydrogenase (Aralp), which converts (R/S)-acetoin to meso-2,3butanediol and (2S,3S)-2,3-butanediol. Deletion of BDH2, a gene adjacent to BDH1, whose encoded protein is 51% identical to Bdh1p, does not significantly alter the levels of acetoin or 2,3-butanediol in comparison to the wild-type strain. Furthermore, we have expressed Bdh2p with a histidine tag and have shown it to be inactive toward 2,3-butanediol. A whole-genome expression analysis with microarrays demonstrates that BDHl and BDH2 are reciprocally regulated. © 2010, American Society for Microbiology. All Rights Reserved.