Saliola M, Falcone C
Pasteur Institute-Cenci Bolognetti Foundation, Department of Cell and Developmental Biology, University of Rome, La Sapienza, Italy.
Mol Gen Genet. 1995 Dec 20;249(6):665-72. doi: 10.1007/BF00418036.
The lactose-utilizing yeast Kluyveromyces lactis is an essentially aerobic organism in which both respiration and fermentation can coexist depending on the sugar concentration. Despite a low fermentative capacity as compared to Saccharomyces cerevisiae, four structural genes encoding alcohol dehydrogenase (ADH) activities are present in this yeast. Two of these activities, namely K1ADH III and K1ADH IV, are located within mitochondria and their presence is dependent on the carbon sources in the medium. In this paper we demonstrate by transcription and activity analysis that KlADH3 is expressed in the presence of low glucose concentrations and in the presence of respiratory carbon sources other than ethanol. Indeed ethanol acts as a strong repressor of this gene. On the other hand, KlADH4 is induced by the presence of ethanol and not by other respiratory carbon sources. We also demonstrate that the presence of KLADH III and KLADH IV in K. lactis cells is dependent on glucose concentration, glucose uptake and the amount of ethanol produced. As a consequence, these activities can be used as markers for the onset of respiratory and fermentative metabolism in this yeast.
利用乳糖的酵母乳酸克鲁维酵母本质上是一种需氧生物，在其中呼吸作用和发酵作用可以根据糖浓度共存。尽管与酿酒酵母相比其发酵能力较低，但这种酵母中存在四个编码乙醇脱氢酶（ADH）活性的结构基因。其中两种活性，即K1ADH III和K1ADH IV，位于线粒体内，它们的存在取决于培养基中的碳源。在本文中，我们通过转录和活性分析证明，KlADH3在低葡萄糖浓度以及除乙醇以外的呼吸碳源存在时表达。实际上，乙醇是该基因的强抑制剂。另一方面，KlADH4由乙醇的存在诱导，而非其他呼吸碳源。我们还证明，乳酸克鲁维酵母细胞中KLADH III和KLADH IV的存在取决于葡萄糖浓度、葡萄糖摄取量以及产生的乙醇量。因此，这些活性可作为该酵母中呼吸和发酵代谢开始的标志物。
