大肠杆菌苏氨酸操纵子中的操纵子-启动子功能。
Operator-promoter functions in the threonine operon of Escherichia coli.
作者信息
Gardner J F, Smith O H
出版信息
J Bacteriol. 1975 Oct;124(1):161-6. doi: 10.1128/jb.124.1.161-166.1975.
The prophage curing properties of secondary-site lysogens of coliphage lambda have been studied. The site of integration in the original lysogen (L79) is within the ooerator-promoter region of the thr operon. As a result, expression of the thr enzymes is reduced, and the strain is a leaky threonine auxotroph. Heat pulse curing of strain L79 and a thr+ lysogenic revertant (L79-20) showed that heat pulse curing of both lysogens was int and xis dependent and occurred by correct excisions of the prophage. The heat pulse curing restored strain L79 to prototrophy whereas strain L79-20 synthesized the thr enzymes constitutively and at high levels. This indicates that the reversion mutation in strain L79-20 occurred outside of the prophage and within the operator-promoter region of the thr operon. In contrast, spontaneous curing of both lysogens occurred by both correct and incorrect excisions. Spontaneously cured derivatives of strain L79-20 gave rise to three classes of regulatory mutants affecting operator and promoter functions to the thr operon.
对大肠杆菌噬菌体λ的二次位点溶原菌的原噬菌体消除特性进行了研究。原始溶原菌（L79）中的整合位点位于苏氨酸操纵子的操纵子 - 启动子区域内。因此，苏氨酸酶的表达降低，该菌株是渗漏型苏氨酸营养缺陷型。对菌株L79和苏氨酸原养型溶原回复突变体（L79 - 20）进行热脉冲消除实验表明，两种溶原菌的热脉冲消除都依赖于int和xis，并且是通过原噬菌体的正确切除发生的。热脉冲消除使菌株L79恢复为原养型，而菌株L79 - 20组成型且高水平地合成苏氨酸酶。这表明菌株L79 - 20中的回复突变发生在原噬菌体之外且在苏氨酸操纵子的操纵子 - 启动子区域内。相比之下，两种溶原菌的自发消除是通过正确和不正确的切除发生的。菌株L79 - 20的自发消除衍生物产生了三类影响苏氨酸操纵子操纵子和启动子功能的调节突变体。
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