Cysteine-102 is positioned in the metal binding activation site of the Corynebacterium diphtheriae regulatory element DtxR.
Cysteine-102 is positioned in the metal binding activation site of the Corynebacterium diphtheriae regulatory element DtxR.
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Cysteine-102 位于白喉棒杆菌调节元件 DtxR 的金属结合激活位点。
DOI：
10.1073/pnas.90.18.8524
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发表时间：
1993
影响因子：
11.1
通讯作者：
Murphy,JR
中科院分区：
文献类型：
--
作者：
Tao,X;Murphy,JR
DtxR的DNA序列分析表明，M(R)25,316调节蛋白在第102位含有一个半胱氨酸残基。DtxR很容易形成不活跃的二硫键连接的二聚体。为了确定该残基在金属离子结合中的作用，我们对第102位的半胱氨酸密码子(TGC)进行了饱和定点突变。我们发现，在体外和重组大肠杆菌DH5α：Lambda RS45toxPO/LacZ中，将半胱氨酸或天冬氨酸以外的氨基酸插入到这个位置都会取消DtxR的功能。只有Cys-102的TGC密码子被TGT(Cys)或GCA(Asp)取代的突变等位基因才能指导DtxR的活性形式的表达，这些DtxR活性形式调控ToxPO/LacZ转录融合中的β-半乳糖苷酶的表达。
DNA sequence analysis of dtxR has shown that the M(r) 25,316 regulatory protein contains a single cysteine residue at position 102. DtxR readily forms inactive disulfide-linked dimers. We have used saturation site-directed mutagenesis of the cysteine codon (TGC) at position 102 in order to determine the role of this residue in metal ion binding. We show that the insertion of amino acids other than cysteine or aspartic acid into this position abolishes DtxR function both in vitro and in recombinant Escherichia coli DH5 alpha:lambda RS45toxPO/lacZ. Only those mutant alleles in which the TGC codon for Cys-102 was replaced by either TGT (Cys) or GCA (Asp) were found to direct the expression of active forms of DtxR that regulate the expression of beta-galactosidase from the toxPO/lacZ transcriptional fusion.