On the recognition and cleavage mechanism of Escherichia coli endodeoxyribonuclease V, a possible DNA repair enzyme.
On the recognition and cleavage mechanism of Escherichia coli endodeoxyribonuclease V, a possible DNA repair enzyme.
复制标题
DOI：
--
复制
发表时间：
1982-03
期刊：
影响因子：
--
通讯作者：
B. Demple;S. Linn
中科院分区：
文献类型：
--
作者：
B. Demple;S. Linn
大肠杆菌内脱氧核糖核酸酶 V 作用于双链 DNA 中的许多损伤位点，包括无嘌呤/无嘧啶位点、非嘧啶二聚体的紫外线诱导的损伤、7-溴甲基苯并[a]蒽的加合物，以及如先前所证明的（Gates, F. T. 和 Linn, S. (1977a) J. Biol. Chem. 252）。 1647-1653)，它能最有效地降解含尿嘧啶的双链 DNA。切割率随着T5 DNA 中尿嘧啶对胸腺嘧啶的取代的增加而增加，用八分之一的胸腺嘧啶取代产生明显的最大切割率。然而，含有 3.8% 胸腺嘧啶被尿嘧啶取代的 DNA 的表观反应极限对应于仅 6% 的 dUMP 残基的切割。显然，这种酶可以识别异常 DNA 结构的一些特征，但不仅仅是扭曲，因为一些损伤，包括嘧啶二聚体，不是底物。无论底物如何，核酸内切酶 V 都会以与单链切口的恒定比率产生双链断裂。它逐步降解 DNA，完成一个底物分子的消化，然后再进行下一个底物分子。这种酶似乎也协同作用。甲基苯并[a]蒽加合物的裂解通常或总是位于损伤的 5' 端。核酸内切酶 V 似乎非常适合充当 DNA 修复酶，用于检查基因组中可能不存在特定修复系统的损伤所产生的结构扭曲。
Escherichia coli endodeoxyribonuclease V acts at many sites of damage in duplex DNA, including apurinic/apyrimidinic sites, lesions induced by ultraviolet light which are not pyrimidine dimers, adducts of 7-bromomethylbenz[a]anthracene, and, as demonstrated earlier (Gates, F. T., and Linn, S. (1977a) J. Biol. Chem. 252. 1647-1653), it degrades uracil-containing duplex DNA most efficiently. The cleavage rate increases with increasing substitution of uracil for thymine in T5 DNA, with a replacement of one-eight of thymine generating the apparent maximum cleavage rate. However, the apparent reaction limit with DNA containing 3.8% of thymine replaced by uracil corresponds to cleavage at only 6% of the dUMP residues. Evidently, the enzyme recognizes some peculiarities of abnormal DNA structure, but not simply distortions, since some lesions, including pyrimidine dimers, are not substrates. Endonuclease V generates double strand breaks in a constant ratio to single strand nicks, regardless of the substrate. It degrades DNA processively, completing the digestion of one substrate molecule before proceeding to the next. The enzyme also appears to act cooperatively. Cleavage at methylbenz[a]anthracene adducts is usually or always 5' to the lesion. Endonuclease V seems well suited to act as a DNA repair enzyme, surveying the genome for structural distortions generated by lesions for which specific repair systems might not exist.