The C-terminal domain of DNA gyrase A adopts a DNA-bending β-pinwheel fold
The C-terminal domain of DNA gyrase A adopts a DNA-bending β-pinwheel fold
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DOI：
10.1073/pnas.0401595101
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发表时间：
2004-05-11
影响因子：
11.1
通讯作者：
Berger, JM
中科院分区：
文献类型：
--
作者：
Corbett, KD;Shultzaberger, RK;Berger, JM
DNA促旋酶是一种独特的酶，能够主动将负超螺旋引入DNA。该功能部分由其A亚基的C末端结构域（GyrA CTD）介导。在这里，我们报告的晶体结构，这个近似35 kDa的结构域确定为1.75埃的分辨率。GyrA CTD出人意料地采用了一种不寻常的折叠，我们称之为β-风车，这在全球范围内让人联想到β-螺旋桨，但它是由具有以前未观察到的拓扑结构的叶片组成的。在这个结构域的外边缘上有一个大的保守的基本补丁，这表明这可能是一个结合和弯曲DNA的位点;基于荧光共振能量转移的分析表明，GyrA CTD能够在40 bp的区域内将DNA弯曲大于或等于180度。令人惊讶的是，我们发现，CTD的拓扑异构酶IV A亚基，其中股份有限的序列同源性与GyrA CTD，也弯曲DNA。总之，这些数据提供了一个物理解释的能力，DNA促旋酶约束一个积极的超螺旋DNA包装，也表明，特定的底物偏好的拓扑异构酶IV可能是部分由这个域的功能。
DNA gyrase is unique among enzymes for its ability to actively introduce negative supercoils into DNA. This function is mediated in part by the C-terminal domain of its A subunit (GyrA CTD). Here, we report the crystal structure of this approximate to35-kDa domain determined to 1.75-Angstrom resolution. The GyrA CTD unexpectedly adopts an unusual fold, which we term a beta-pinwheel, that is globally reminiscent of a beta-propeller but is built of blades with a previously unobserved topology. A large, conserved basic patch on the outer edge of this domain suggests a likely site for binding and bending DNA; fluorescence resonance energy transfer-based assays show that the GyrA CTD is capable of bending DNA by greater than or equal to180degrees over a 40-bp region. Surprisingly, we find that the CTD of the topoisomerase IV A subunit, which shares limited sequence homology with the GyrA CTD, also bends DNA. Together, these data provide a physical explanation for the ability of DNA gyrase to constrain a positive superhelical DNA wrap, and also suggest that the particular substrate preferences of topoisomerase IV might be dictated in part by the function of this domain.