Dickinson J R, Roy D J, Dawes I W
Mol Gen Genet. 1986 Jul;204(1):103-7. doi: 10.1007/BF00330195.
In Saccharomyces cerevisiae a nuclear recessive mutation, lpd1, which simultaneously abolishes the activities of lipoamide dehydrogenase, 2-oxoglutarate dehydrogenase and pyruvate dehydrogenase has been identified. Strains carrying this mutation can grow on glucose or poorly on ethanol, but are unable to grow on media with glycerol or acetate as carbon source. The mutation does not prevent the formation of other tricarboxylic acid cycle enzymes such as fumarase, NAD+-linked isocitrate dehydrogenase or succinate-cytochrome c oxidoreductase, but these are produced at about 50%-70% of the wild-type levels. The mutation probably affects the structural gene for lipoamide dehydrogenase since the amount of this enzyme in the cell is subject to a gene dosage effect; heterozygous lpd1 diploids produce half the amount of a homozygous wild-type strain. Moreover, a yeast sequence complementing this mutation when present in the cell on a multicopy plasmid leads to marked overproduction of lipoamide dehydrogenase. Homozygous lpd1 diploids were unable to sporulate indicating that some lipoamide dehydrogenase activity is essential for sporulation to occur on acetate.
在酿酒酵母中，已鉴定出一种核隐性突变lpd1，该突变同时消除了硫辛酰胺脱氢酶、2-氧代戊二酸脱氢酶和丙酮酸脱氢酶的活性。携带这种突变的菌株能够在葡萄糖上生长，在乙醇上生长较差，但不能在以甘油或乙酸盐作为碳源的培养基上生长。该突变并不妨碍其他三羧酸循环酶的形成，如延胡索酸酶、NAD⁺连接的异柠檬酸脱氢酶或琥珀酸-细胞色素c氧化还原酶，但这些酶的产生量约为野生型水平的50%-70%。该突变可能影响硫辛酰胺脱氢酶的结构基因，因为细胞中这种酶的量受到基因剂量效应的影响；杂合lpd1二倍体产生的酶量是纯合野生型菌株的一半。此外，当多拷贝质粒上的酵母序列存在于细胞中时，对该突变具有互补作用，会导致硫辛酰胺脱氢酶显著过量产生。纯合lpd1二倍体无法形成孢子，这表明某些硫辛酰胺脱氢酶活性对于在乙酸盐上形成孢子至关重要。
