多个决定酿酒酵母中亮氨酸生物合成第一步活性的新基因。
Multiple new genes that determine activity for the first step of leucine biosynthesis in Saccharomyces cerevisiae.
作者信息
Drain P, Schimmel P
机构信息
Department of Biology, Massachusetts Institute of Technology, Cambridge 02139.
出版信息
Genetics. 1988 May;119(1):13-20. doi: 10.1093/genetics/119.1.13.
The first step in the biosynthesis of leucine is catalyzed by alpha-isopropylmalate (alpha-IPM) synthase. In the yeast Saccharomyces cerevisiae, LEU4 encodes the isozyme responsible for the majority of alpha-IPM synthase activity. Yeast strains that bear disruption alleles of LEU4, however, are Leu+ and exhibit a level of synthase activity that is 20% of the wild type. To identify the gene or genes that encode this remaining activity, a leu4 disruption strain was mutagenized. The mutations identified define three new complementation groups, designated leu6, leu7 and leu8. Each of these new mutations effect leucine auxotrophy only if a leu4 mutation is present and each results in loss of alpha-IPM synthase activity. Further analysis suggests that LEU7 and LEU8 are candidates for the gene or genes that encode an alpha-IPM synthase activity. The results demonstrate that multiple components determine the residual alpha-IPM synthase activity in leu4 gene disruption strains of S. cerevisiae.
亮氨酸生物合成的第一步由α-异丙基苹果酸（α-IPM）合酶催化。在酿酒酵母中，LEU4编码负责大部分α-IPM合酶活性的同工酶。然而，携带LEU4破坏等位基因的酵母菌株是亮氨酸原养型（Leu+），并且表现出的合酶活性水平是野生型的20%。为了鉴定编码这种剩余活性的一个或多个基因，对一个leu4破坏菌株进行了诱变。鉴定出的突变定义了三个新的互补群，命名为leu6、leu7和leu8。只有当存在leu4突变时，这些新突变中的每一个才会导致亮氨酸营养缺陷，并且每一个都会导致α-IPM合酶活性丧失。进一步分析表明，LEU7和LEU8是编码α-IPM合酶活性的一个或多个基因的候选基因。结果表明，多个组分决定了酿酒酵母leu4基因破坏菌株中残余的α-IPM合酶活性。
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