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首页> 外文期刊>Journal of Molecular Biology >Crystal structure of a cobalt-activated diphtheria toxin repressor-DNA complex reveals a metal-binding SH3-like domain.
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Crystal structure of a cobalt-activated diphtheria toxin repressor-DNA complex reveals a metal-binding SH3-like domain.

机译：钴激活的白喉毒素阻遏物-DNA复合物的晶体结构揭示了一个金属结合SH3样域。

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摘要

The diphtheria toxin repressor (DtxR) is the prototype of a family of iron-dependent regulator (IdeR) proteins, which are activated by divalent iron and bind DNA to prevent the transcription of downstream genes. In Corynebacterium diphtheriae, DtxR regulates not only the expression of diphtheria toxin encoded by a corynebacteriophage, but also of components of the siderophore-mediated iron-transport system. Here we report the crystal structure of wild-type DtxR, a 226 residue three-domain dimeric protein, activated by cobalt and bound to a 21 bp DNA duplex based on the consensus operator sequence. Two DtxR dimers surround the DNA duplex which is distorted compared to canonical B -DNA. The SH3-like third domain interacts with the metal at site 1 via the side-chains of Glu170 and Gln173, revealing for the first time a metal-binding function for this class of domains. The SH3-like domain is also in contact with the DNA-binding first domain and with the second, or dimerization, domain. The DNA-binding helices in the first domain are shifted by 3 to 5 A when compared to the apo-repressor, and fit into the major groove of the duplex bound. These shifts are due to a hinge-binding motion of the DNA-binding domain with respect to the dimerization domains of DtxR. The third domain might play a role in regulating this hinge motion. Copyright 1999 Academic Press.
机译：白喉毒素阻遏物（DtxR）是铁依赖性调节剂（IdeR）蛋白家族的原型，该蛋白被二价铁激活并结合DNA以阻止下游基因的转录。在白喉棒状杆菌中，DtxR不仅调节由棒状噬菌体编码的白喉毒素的表达，而且还调节铁载体介导的铁转运系统的成分。在这里，我们报告野生型DtxR的晶体结构，这是一个226个残基的三结构域二聚体蛋白，被钴激活并基于共有操纵子序列与21 bp DNA双链体结合。与标准的B -DNA相比，两个DtxR二聚体围绕着DNA双链体变形。类似于SH3的第三结构域通过Glu170和Gln173的侧链与位点1的金属相互作用，首次揭示了此类结构域的金属结合功能。 SH3样结构域也与结合DNA的第一结构域和第二或二聚结构域接触。与载脂蛋白阻遏物相比，第一个结构域中的DNA结合螺旋移位了3至5 A，并适合双链体结合的主沟。这些移位是由于DNA结合结构域相对于DtxR的二聚化结构域的铰链结合运动。第三域可能在调节该铰链运动中起作用。版权所有1999，学术出版社。

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