Yasui A, Eker A P, Yasuhira S, Yajima H, Kobayashi T, Takao M, Oikawa A
Institute of Development, Aging and Cancer, Tohoku University, Sendai, Japan.
EMBO J. 1994 Dec 15;13(24):6143-51. doi: 10.1002/j.1460-2075.1994.tb06961.x.
DNA photolyase specifically repairs UV light-induced cyclobutane-type pyrimidine dimers in DNA through a light-dependent reaction mechanism. We have obtained photolyase genes from Drosophila melanogaster (fruit fly), Oryzias latipes (killifish) and the marsupial Potorous tridactylis (rat kangaroo), the first photolyase gene cloned from a mammalian species. The deduced amino acid sequences of these higher eukaryote genes show only limited homology with microbial photolyase genes. Together with the previously cloned Carassius auratus (goldfish) gene they form a separate group of photolyase genes. A new classification for photolyases comprising two distantly related groups is proposed. For functional analysis P.tridactylis photolyase was expressed and purified as glutathione S-transferase fusion protein from Escherichia coli cells. The biologically active protein contained FAD as light-absorbing cofactor, a property in common with the microbial class photolyases. Furthermore, we found in the archaebacterium Methanobacterium thermoautotrophicum a gene similar to the higher eukaryote photolyase genes, but we could not obtain evidence for the presence of a homologous gene in the human genome. Our results suggest a divergence of photolyase genes in early evolution.
DNA光解酶通过光依赖反应机制特异性修复DNA中紫外线诱导的环丁烷型嘧啶二聚体。我们从黑腹果蝇（果蝇）、青鳉（鳉鱼）和有袋动物三趾袋狸（鼠袋鼠）中获得了光解酶基因，这是首次从哺乳动物物种中克隆的光解酶基因。这些高等真核生物基因推导的氨基酸序列与微生物光解酶基因仅显示有限的同源性。它们与先前克隆的鲫鱼（金鱼）基因一起形成了一个单独的光解酶基因组。提出了一种包含两个远缘相关组的光解酶新分类。为了进行功能分析，将三趾袋狸光解酶作为谷胱甘肽S-转移酶融合蛋白从大肠杆菌细胞中表达并纯化。该生物活性蛋白含有FAD作为吸光辅因子，这是与微生物类光解酶共有的特性。此外，我们在嗜热自养甲烷杆菌古细菌中发现了一个与高等真核生物光解酶基因相似的基因，但我们无法获得人类基因组中存在同源基因的证据。我们的结果表明光解酶基因在早期进化中发生了分化。
