Duntze W, Manney T R
J Bacteriol. 1968 Dec;96(6):2085-93. doi: 10.1128/jb.96.6.2085-2093.1968.
Two different types of allelic complementation were observed in tryptophan synthetase mutants of the yeast Saccharomyces cerevisiae. Each type is associated with a different mechanism for the enzymatic conversion of indole-3-glycerol phosphate (InGP) to tryptophan. Mechanism I is utilized by a hybrid tryptophan synthetase that resembles, but is not identical with, the wild-type enzyme. Mechanism II is due to a sequential conversion of InGP to free indole, and indole to tryptophan. Two partially active mutant enzymes rather than a single hybrid enzyme catalyze the sequential reaction steps. This is an example of intracellular cross-feeding. The quantitative evaluation of mechanism II leads to the conclusion that tryptophan synthetase in yeast is most likely a dimer of two identical subunits.
在酿酒酵母色氨酸合成酶突变体中观察到两种不同类型的等位基因互补。每种类型都与吲哚 - 3 - 甘油磷酸(InGP)酶促转化为色氨酸的不同机制相关。机制I由一种杂合色氨酸合成酶利用,该酶与野生型酶相似但不相同。机制II是由于InGP顺序转化为游离吲哚,然后吲哚再转化为色氨酸。两个部分活性的突变酶而非单个杂合酶催化这一系列反应步骤。这是细胞内交叉喂养的一个例子。对机制II的定量评估得出结论,酵母中的色氨酸合成酶很可能是由两个相同亚基组成的二聚体。