Comparative analysis of binding of human damaged DNA-binding protein (XPE) and Escherichia coli damage recognition protein (UvrA) to the major ultraviolet photoproducts: T[c,s]T, T[t,s]T, T[6-4]T, and T[Dewar]T.
Comparative analysis of binding of human damaged DNA-binding protein (XPE) and Escherichia coli damage recognition protein (UvrA) to the major ultraviolet photoproducts: T[c,s]T, T[t,s]T, T[6-4]T, and T[Dewar]T.
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DOI：
10.1016/s0021-9258(19)36924-8
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发表时间：
1993-10
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影响因子：
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通讯作者：
J. Reardon;A. Nichols;Scott Keeney;Colin A. Smith;John-Stephen Taylor;S. Linn;Aziz Sancar
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文献类型：
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作者：
J. Reardon;A. Nichols;Scott Keeney;Colin A. Smith;John-Stephen Taylor;S. Linn;Aziz Sancar
人体细胞含有一种蛋白质，能够以高亲和力与紫外线照射的 DNA 结合。这种蛋白质，即受损的 DNA 结合蛋白 (DDB)，在某些色素性干皮病互补组 E 细胞株中不存在；因此，有人认为它可能是人类切除核酸酶复合物的损伤识别亚基。然而，DDB 结合的紫外光产物的身份以及该蛋白在核苷酸切除修复中的作用一直存在争议。在这项研究中，我们使用了几种合成 DNA 底物，每种底物都含有一种主要的 UV 光产物，以及纯化至表观同质性的 DDB，以量化 DDB 与各种光产物的特异性结合。为了进行比较，还测量了大肠杆菌损伤识别蛋白 UvrA（已知是大肠杆菌切除核酸酶的亚基）对相同光产物的结合。 UvrA 和 DDB 均以高亲和力与 T[t,s]T、T[6-4]T 和 T[Dewar]T 结合，但在未损坏的寡聚物和具有 T[c,s]T 的寡聚物之间仅略有区别。与 UV 光产物结合方面的相似性相反，UvrA 与另一种切除修复底物（补骨脂素-胸腺嘧啶单加合物）结合，具有高特异性，而 DDB 无法区分补骨脂素加合 DNA 和未损坏的 DNA。我们得出结论，DDB可能在紫外线损伤的修复中发挥特殊作用，但它不能是人类核酸切除酶唯一的损伤识别亚基。
Human cells contain a protein that binds to UV-irradiated DNA with high affinity. This protein, the damaged DNA-binding protein (DDB), is absent from some xeroderma pigmentosum complementation group E cell strains; therefore, it has been suggested that it may be the damage recognition subunit of a human excision nuclease complex. However, the identity of the UV photoproduct bound by DDB and the role of this protein in nucleotide excision repair have been controversial. In this study, we used several synthetic DNA substrates, each of which contains one of the major UV photoproducts, and DDB purified to apparent homogeneity to quantify the specific binding of DDB to various photoproducts. For comparison, the binding of the same photoproducts by the Escherichia coli damage recognition protein UvrA, which is known to be a subunit of the E. coli excision nuclease, was also measured. UvrA and DDB each bound with high affinity to T[t,s]T, T[6-4]T, and T[Dewar]T, but only marginally discriminated between an undamaged oligomer and an oligomer with a T[c,s]T. In contrast to these similarities with regard to the binding to UV photoproducts, UvrA bound to another excision repair substrate, the psoralen-thymine monoadduct, with high specificity, whereas DDB was unable to distinguish between psoralen-adducted DNA and undamaged DNA. We conclude that DDB may play a special role in the repair of UV damage, but it cannot be the sole damage recognition subunit of human excision nuclease.