Laboratório de Biologia de Fungos, Centro de Biotecnologia e Genética, Universidade Estadual de Santa Cruz, Rod. Ilhéus Itabuna km 16, Salobrinho, Ilhéus, Bahia, Brazil.
Yeast. 2011 May;28(5):363-73. doi: 10.1002/yea.1844. Epub 2011 Mar 1.
Alcohol dehydrogenases catalyse the reversible oxidation of alcohols to aldehydes or ketones, with concomitant reduction of NAD(+) or NADP(+) . Adh1p is responsible for the reduction of acetaldehyde to ethanol, while Adh2p catalyses the reverse reaction, the oxidation of ethanol to acetaldehyde. Lack of Adh1p shifts the cellular redox balance towards excess NADH/NADPH and acetaldehyde, while absence of Adh2p does the opposite. Yeast mutant adh1Δ had a slow growth rate, whereas adh2Δ grew like the isogenic wild-type (WT) during prediauxic shift fermentative metabolism. After 48 h WT and mutants reached the same number of viable cells. When exponentially growing (LOG) cells were exposed to calcofluor white, only mutant adh1Δ displayed an irregular deposition of chitin. Quantitative analyses of both LOG and stationary-phase cells showed that adh1Δ mutant contained significantly less ergosterol than cells of WT and adh2Δ mutant, whereas the erg3Δ mutant contained extremely low ergosterol pools. Both adh1Δ and adh2Δ mutants showed higher-than-WT resistance to heat shock and to H(2) O(2) but had WT resistance when exposed to ultraviolet (UV) light and the DNA cross-linking agent diepoxyoctane, indicating normal DNA repair capacity. Mutant adh1Δ was specifically sensitive to acetaldehyde and to membrane peroxidizing paraquat. Our results link the pleiotropic phenotype of adh1Δ mutants to low pools of ergosterol and to reductive stress, and introduce the two new phenotypes, resistance to heat shock and to H(2) O(2) , for the adh2Δ mutant, most probably related to increased ROS production in mitochondria, which leads to the induction of oxidative stress protection.
醇脱氢酶催化醇的可逆氧化为醛或酮，同时伴随着 NAD(+)或 NADP(+)的还原。Adh1p 负责将乙醛还原为乙醇，而 Adh2p 则催化相反的反应，将乙醇氧化为乙醛。Adh1p 的缺失会使细胞氧化还原平衡向过量的 NADH/NADPH 和乙醛倾斜，而 Adh2p 的缺失则相反。酵母突变体 adh1Δ 的生长速度较慢，而 adh2Δ 在预发酵代谢的需氧转移过程中生长得像同基因野生型 (WT)一样快。48 小时后，WT 和突变体达到相同数量的存活细胞。当指数生长期 (LOG) 细胞暴露于Calcofluor White 时，只有突变体 adh1Δ 显示出几丁质的不规则沉积。对 LOG 和静止期细胞的定量分析表明，adh1Δ 突变体中的麦角固醇含量明显低于 WT 和 adh2Δ 突变体，而 erg3Δ 突变体中的麦角固醇含量极低。adh1Δ 和 adh2Δ 突变体对热休克和 H(2)O(2)的抗性均高于 WT，但在暴露于紫外线 (UV) 光和 DNA 交联剂二环氧辛烷时，WT 的抗性与 WT 相同，表明其具有正常的 DNA 修复能力。adh1Δ 突变体对乙醛和膜过氧化剂百草枯特别敏感。我们的结果将 adh1Δ 突变体的多效表型与低麦角固醇水平和还原性应激联系起来，并为 adh2Δ 突变体引入了两种新的表型，即对热休克和 H(2)O(2)的抗性，这很可能与线粒体中活性氧 (ROS) 产生增加有关，这导致了氧化应激保护的诱导。
