Costenoble R, Valadi H, Gustafsson L, Niklasson C, Franzén C J
Department of Chemical Reaction Engineering, Chalmers University of Technology, SE-412 96 Goteborg, Sweden.
Yeast. 2000 Dec;16(16):1483-95. doi: 10.1002/1097-0061(200012)16:16<1483::AID-YEA642>3.0.CO;2-K.
The yeast Saccharomyces cerevisiae produces large amounts of glycerol as an osmoregulator during hyperosmotic stress and as a redox sink at low oxygen availability. NAD(+)-dependent glycerol-3-phosphate dehydrogenase in S. cerevisiae is present in two isoforms, coded for by two different genes, GPD1 and GPD2. Mutants for either one or both of these genes were investigated under carefully controlled static and dynamic conditions in continuous cultures at low oxygen transfer rates. Our results show that S. cerevisiae controls the production of glycerol in response to hypoxic conditions by regulating the expression of several genes. At high demand for NADH reoxidation, a strong induction was seen not only of the GPD2 gene, but also of GPP1, encoding one of the molecular forms of glycerol-3-phosphatase. Induction of the GPP1 gene appears to play a decisive role at elevated growth rates. At low demand for NADH reoxidation via glycerol formation, the GPD1, GPD2, GPP1, and GPP2 genes were all expressed at basal levels. The dynamics of the gene induction and the glycerol formation at low demand for NADH reoxidation point to an important role of the Gpd1p; deletion of the GPD1 gene strongly altered the expression patterns of the GPD2 and GPP1 genes under such conditions. Furthermore, our results indicate that GCY1 and DAK1, tentatively encoding glycerol dehydrogenase and dihydroxyacetone kinase, respectively, may be involved in the redox regulation of S. cerevisiae.
酿酒酵母在高渗胁迫期间会产生大量甘油作为渗透调节剂，在低氧条件下作为氧化还原汇。酿酒酵母中依赖NAD⁺的甘油-3-磷酸脱氢酶存在两种同工型，由两个不同的基因GPD1和GPD2编码。在低氧传递速率的连续培养中，在精心控制的静态和动态条件下研究了这两个基因中一个或两个基因的突变体。我们的结果表明，酿酒酵母通过调节几个基因的表达来响应缺氧条件下甘油的产生。在对NADH再氧化的高需求下，不仅GPD2基因有强烈诱导，而且编码甘油-3-磷酸酶分子形式之一的GPP1基因也有强烈诱导。GPP1基因的诱导在生长速率升高时似乎起决定性作用。在通过甘油形成对NADH再氧化的低需求下，GPD1、GPD2、GPP1和GPP2基因均以基础水平表达。在对NADH再氧化低需求下基因诱导和甘油形成的动态变化表明Gpd1p起重要作用；在这种条件下，GPD1基因的缺失强烈改变了GPD2和GPP1基因的表达模式。此外，我们的结果表明，分别暂定为编码甘油脱氢酶和二羟基丙酮激酶的GCY1和DAK1可能参与酿酒酵母的氧化还原调节。
