...
  • 主题
高级搜索  >
历史搜索 清空历史
首页> 外文期刊>Biochemistry >Differential incision of bulky carcinogen-DNA adducts by the UVrABC nuclease: Comparison of incision rates and the interactions of Uvr subunits with lesions of different structures
【24h】

Differential incision of bulky carcinogen-DNA adducts by the UVrABC nuclease: Comparison of incision rates and the interactions of Uvr subunits with lesions of different structures

机译：UVrABC核酸酶区分大块致癌物-DNA加合物的切口：切口速率和Uvr亚基与不同结构病变的相互作用的比较

获取原文
获取原文并翻译 | 示例
           
页面导航
  • 摘要
  • 著录项
  • 相似文献
  • 相关主题

摘要

The UvrABC nuclease system from Escherichia coli removes DNA damages induced by a wide range of chemical carcinogens with variable efficiencies. The interactions with UvrABC proteins of the following three lesions site-specifically positioned in DNA, and of known conformations, were investigated: (i) adducts derived from the binding of the (-)-(7S,8R,9R,10S) enantiomer of 7,8-dihydroxy-9,10-epoxy-7,8,9,10-tetrahydrobenzo[a]pyrene [(-)-anti-BPDE] by cis-covalent addition to N-2-2'-deoxyguanosine [(-)-cis-anti-BP-N-2-dG], (ii) an adduct derived from the binding of the (+)-(1R,2S,3S,4R) enantiomer of 1,2-dihydroxy-3,4-epoxy- 1,2,3,4-tetrahydro-5-methylchrysene [(+)-anti-5-MeCDE] by trans addition to N-2-2'-deoxyguanosine [(+)-trans-anti-MC-N-2-dG], and (iii) a C8-2'-deoxyguanosine adduct (C8-AP-dG) formed by reductively activated I-nitropyrene (1-NP). The influence of these three different adducts on UvrA binding affinities, formation of UvrB-DNA complexes by quantitative gel mobility shift analyses, and the rates of UvrABC incision were investigated. The binding affinities of UvrA varied among the three adducts, UvrA bound to the DNA adduct (+)-trans-anti-MC-N-2-dG with the highest affinity (K-d = 17 +/- 2 nM) and to the DNA containing C8-AP-dG with the least affinity (K-d = 28 +/- 1 nM). The extent of complex formation with UvrB was also the lowest with the C8-AP-dG adduct. 5' Incisions occurred at the eighth phosphate from the modified guanine, The major 3' incision site corresponded to the fifth phosphodiester bond for all three adducts. However, additional 3' incisions were observed at the fourth and sixth phosphates in the case of the C8-AP-dG adduct, whereas in the case of the (-)-cis-anti-BP-N-2-dG and (+)-trans-anti-MC-N-2-dG lesions additional 3' cleavage occurred at the sixth and seventh phosphodiester bonds. Both the initial rate and the extent of 5' and 3' incisions revealed that C8-AP-dG was repaired less efficiently in comparison to the (-)-cis-anti-BP-N-2-dG and (+)-trans-anti-MC-N-2-dG containing DNA adducts. Our study showed that UvrA recognizes conformational changes induced by structurally different lesions and that in certain cases the binding affinities of UvrA and UvrB can be correlated with the incision rates. The size of the bubble formed around the damaged site with mismatched bases also appears to influence the incision rates. A particularly noteworthy finding in this study is that UvrABC repair of a substrate with no base opposite C8-AP-dG was quite inefficient as compared to the same adduct with a C opposite it. These findings are discussed in terms of the available NMR solution structures. [References: 52]
机译：大肠杆菌的UvrABC核酸酶系统可消除各种化学致癌物以不同的效率诱导的DNA损伤。研究了以下三个在DNA中特异性定位的损伤以及已知构象与UvrABC蛋白的相互作用：（i）源自（-）-（7S，8R，9R，10S）对映体结合的加合物通过顺式共价添加到N-2-2'-脱氧鸟嘌呤[[，（7,8-dihydroxy-9,10-epoxy-7,8,9,10-四氢苯并[a] -re-BPDE]] -）-顺-抗-BP-N-2-dG]，（ii）由1，2-二羟基-3的（+）-（1R，2S，3S，4R）对映体的结合衍生的加合物，通过将反式加成至N-2-2'-脱氧鸟苷[（+）-反式-MC]中，将4-环氧-1,2,3,4-四氢-5-甲基丙烯[（+）-反-5-MeCDE] -N-2-dG]，和（iii）通过还原活化的I-硝基py（1-NP）形成的C8-2'-脱氧鸟苷加合物（C8-AP-dG）。研究了这三种不同的加合物对UvrA结合亲和力，通过定量凝胶迁移率移动分析形成UvrB-DNA复合物的影响以及UvrABC切口的速率。 UvrA的结合亲和力在三个加合物之间有所不同，UvrA以最高亲和力（Kd = 17 +/- 2 nM）结合到DNA加合物（+）-trans-anti-MC-N-2-dG和DNA上含有亲和力最低的C8-AP-dG（Kd = 28 +/- 1 nM）。 UvrB与C8-AP-dG加合物形成复合物的程度也最低。 5'切口发生在修饰的鸟嘌呤的第8个磷酸盐处，主要的3'切口位点对应于所有三个加合物的第5个磷酸二酯键。但是，在C8-AP-dG加合物的情况下，在第四和第六磷酸盐处观察到了另外的3'切口，而在（-）-顺-抗-BP-N-2-dG和（+ ）-反-抗-MC-N-2-dG损伤在第六和第七磷酸二酯键处发生了另外的3'裂解。初始比率和5'和3'切口的范围均表明，与（-）-顺-抗-BP-N-2-dG和（+）-反式相比，C8-AP-dG的修复效率较低-包含DNA加合物的抗MC-N-2-dG。我们的研究表明，UvrA识别由结构不同的病变引起的构象变化，并且在某些情况下，UvrA和UvrB的结合亲和力可以与切开率相关。底部不匹配的受损部位周围形成的气泡大小似乎也会影响切开率。在这项研究中特别值得注意的发现是，与C8-AP-dG对立的相同加合物相比，UvrABC对没有碱基与C8-AP-dG对立的底物的修复效率很低。将根据可用的NMR溶液结构讨论这些发现。 [参考：52]

著录项

相似文献

  • 外文文献
  • 中文文献
获取原文

客服邮箱：kefu@zhangqiaokeyan.com

京公网安备：11010802029741号 ICP备案号：京ICP备15016152号-6 六维联合信息科技 (北京) 有限公司©版权所有

  • 客服微信

  • 服务号