Sancar A, Rupp W D
Cell. 1983 May;33(1):249-60. doi: 10.1016/0092-8674(83)90354-9.
The uvrA, uvrB, and uvrC proteins of Escherichia coli were purified from strains that greatly overproduce these proteins. Using the purified proteins, the UVRABC nuclease was reconstituted in vitro. The reconstituted enzyme acted specifically on DNA damaged with UV, cis-platinum, and psoralen plus near UV. When UV-irradiated DNA was used as substrate, the enzyme made two cuts on the damaged DNA strand, one on each side of the damaged region. The enzyme hydrolyzed the eighth phosphodiester bond on the 5' side of pyrimidine dimers. On the 3' side of pyrimidine dimers, the UVRABC nuclease cut the fourth or the fifth phosphodiester bond 3' to pyrimidine dimers. The oligonucleotide with the damaged bases that is generated by these two cuts was released during treatment with the enzyme. We have also obtained evidence suggesting that the enzyme acts by the same mechanism on PydC photoproducts which are thought to be of primary importance in UV-induced mutagenesis.
大肠杆菌的uvrA、uvrB和uvrC蛋白是从大量过量产生这些蛋白的菌株中纯化得到的。利用纯化的蛋白，在体外重构了UVRABC核酸酶。重构后的酶特异性作用于经紫外线、顺铂和补骨脂素加近紫外线损伤的DNA。当用紫外线照射的DNA作为底物时，该酶在受损的DNA链上产生两处切口，分别位于受损区域的两侧。该酶水解嘧啶二聚体5'侧的第八个磷酸二酯键。在嘧啶二聚体的3'侧，UVRABC核酸酶在嘧啶二聚体3'端切割第四个或第五个磷酸二酯键。由这两处切割产生的带有受损碱基的寡核苷酸在酶处理过程中被释放出来。我们还获得了证据，表明该酶对PydC光产物的作用机制相同，而PydC光产物被认为在紫外线诱导的诱变中起主要作用。
