Characterization and functional role of Saccharomyces cerevisiae 2,3-butanediol dehydrogenase

Using a conserved sequence motif, a new gene (YAL060W) of the MDR family ha s been identified in Saccharomyces cerevisiae. The expressed protein was a stereoespecific (2R,3R)-2,3-butanediol dehydrogenase (BDH). The best substr ates were (2R,3R)-2,3-butanediol for the oxidation and (3R/3S)-acetoin and 1-hydroxy-2-propanbne for the reduction reactions. The enzyme is extremely specific for NAD(H) as cofactor, probably because the presence of Glu223 in the cofactor binding site, instead of the highly conserved Asp223. BDH is inhibited competitively by 4-methylpyrazole with a K-i of 34 muM. Yeast cou ld grow on 2,3-butanediol or acetoin as a sore energy and carbon sources, a nd a 3.6-fold increase in BDH activity was observed when cells were grown i n 2,3-butanediol, suggesting a role of the enzyme in 2,3-butanediol metabol ism. However, the disruption of the YAL060W gene was not lethal for the yea st under laboratory conditions, and the disrupted strain could also grow in 2,3-butanediol and acetoin. This suggests that other enzymes, in addition to BDH, can also metabolize 2,3-butanediol in yeast. (C) 2001 Elsevier Scie nce Ireland Ltd. All rights reserved.