Nogi Y
J Bacteriol. 1986 Jan;165(1):101-6. doi: 10.1128/jb.165.1.101-106.1986.
The activities of the first three enzymes for galactose catabolism normally become detectable within 15 min after the addition of galactose into a culture of the yeast Saccharomyces cerevisiae. In S. cerevisiae with a recessive mutation termed gal3, a longer-than-normal lag is observed before the appearance of the enzyme activities (O. Winge and C. Roberts, C. R. Trav. Lab. Carlsberg Ser. Physiol. 24:263-315, 1948). I isolated two S. cerevisiae mutants with temperature-sensitive defects in the GAL3 gene. Temperature shift experiments with one of those mutants led to the conclusion that the GAL3 function is required not only for the initiation of enzyme induction but also for the maintenance of the induced state in galactose-nonfermenting S. cerevisiae because of a defect in any of the genes for the galactose-catabolizing enzymes, such as gal1 or gal10. In contrast, the GAL3 function is phenotypically dispensable in galactose-metabolizing S. cerevisiae. Thus, the normal catabolism of galactose can substitute for the GAL3 function.
在将半乳糖添加到酿酒酵母培养物中后的15分钟内，通常可检测到参与半乳糖分解代谢的前三种酶的活性。在具有隐性突变gal3的酿酒酵母中，在酶活性出现之前会观察到比正常情况更长的延迟期（O. Winge和C. Roberts，《嘉士伯实验室生理学学报》第24卷：263 - 315页，1948年）。我分离出了两个在GAL3基因中存在温度敏感缺陷的酿酒酵母突变体。对其中一个突变体进行温度转换实验得出的结论是，由于半乳糖分解代谢酶（如gal1或gal10）的任何一个基因存在缺陷，GAL3功能不仅对半乳糖非发酵型酿酒酵母中酶诱导的起始是必需的，而且对维持诱导状态也是必需的。相比之下，GAL3功能在半乳糖代谢型酿酒酵母中在表型上是可有可无的。因此，半乳糖的正常分解代谢可以替代GAL3功能。
