Binding of the metalloregulatory protein DtxR to the diphtheria tox operator requires a divalent heavy metal ion and protects the palindromic sequence from DNase I digestion.
Binding of the metalloregulatory protein DtxR to the diphtheria tox operator requires a divalent heavy metal ion and protects the palindromic sequence from DNase I digestion.
复制标题
DOI：
10.1016/s0021-9258(19)36677-3
复制
发表时间：
1992-10
期刊：
影响因子：
--
通讯作者：
X. Tao;J. Murphy
中科院分区：
文献类型：
--
作者：
X. Tao;J. Murphy
白喉棒状杆菌噬菌体tox操纵子的转录已被证明是通过棒状杆菌决定因子DtxR调节的。dtxR基因最近已被克隆并在大肠杆菌中表达，并显示出从白喉毒素启动子/操纵子-lacZ转录融合物调节β-半乳糖苷酶表达的表达。Tao等人（Tao，X.，博伊德，J.，和Murphy，J.R.等人（1992）Proc. Acad. Sci. U.S.A.89，5897-5901）最近通过凝胶迁移率变动测定显示，DtxR与tox操纵子的结合需要二价重金属离子以及27个碱基对中断的回文序列。我们现在表明，在Co2+、Fe 2+或Mn 2+存在下，DtxR的激活分别导致编码链和非编码链上的33个和27个核苷酸区域免受DNA酶I消化的保护。DtxR也被激活的存在下，Ni 2+，然而，这种金属调节因子只有微弱的激活Zn 2+。白喉毒素调节区在活化的DtxR存在下保护免于DNA酶I消化，包括27个碱基对的中断回文序列。
Transcription of the corynebacteriophage diphtheria tox operon has been shown to be regulated through a corynebacterial determined factor DtxR. The dtxR gene has been recently cloned and expressed in Escherichia coli, and shown to regulate the expression of beta-galactosidase expression from a diphtheria tox promoter/operator-lacZ transcriptional fusion. Tao et al. (Tao, X., Boyd, J., and Murphy, J. R. (1992) Proc. Natl. Acad. Sci. U.S.A. 89, 5897-5901) have recently shown by gel mobility shift assay that the binding of DtxR to the tox operator requires a divalent heavy metal ion, as well as the 27-base pair interrupted palindromic sequence. We now show the activation of DtxR in the presence of Co2+, Fe2+, or Mn2+ results in the protection of a 33- and 27-nucleotide region on the coding and non-coding strand from DNase I digestion, respectively. DtxR is also activated in the presence of Ni2+; however, this metalloregulatory factor is only weakly activated by Zn2+. The diphtheria tox regulatory region protected from DNase I digestion in the presence of activated DtxR encompasses the 27-base pair interrupted palindromic sequence.