Bacterial cryptochrome and photolyase:: characterization of two photolyase-like genes of Synechocystis sp PCC6803
Bacterial cryptochrome and photolyase:: characterization of two photolyase-like genes of Synechocystis sp PCC6803
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DOI：
10.1093/nar/28.12.2353
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发表时间：
2000-06-15
影响因子：
14.9
通讯作者：
Todo, T
中科院分区：
文献类型：
--
作者：
Hitomi, K;Okamoto, K;Todo, T
光解酶是一种DNA修复酶，它以光依赖的方式逆转DNA中紫外线诱导的光产物。最近，在高等真核生物中发现了光解酶同源物。这些同系物被称为隐色素，其功能是蓝光感光受体或昼夜节律的调节器。相比之下，大多数细菌只有一个光解酶或类似光解酶的基因。与其他微生物不同的是，聚球藻PCC6803的染色体含有两个ORF(slr0854和sll1629)，与光解酶有很高的相似性。我们已经确定了这两个基因的特征。Slr0854基因产物对环丁烷嘧啶二聚体(CPD)具有特异的光依赖性修复活性，而sll1629基因产物在体外缺乏对DNA的亲和力。阻断slr0854或sll1629对蓝藻的生长速度影响很小或没有影响。缺乏slr0854基因的突变体表现出严重的紫外线敏感性，而缺乏sll1629的突变体的系统发育分析表明，sll1629与隐花色素的亲缘关系比与光解酶的关系更密切。我们得出结论，sll1629是一种细菌隐色素。据我们所知，这是对细菌隐色素的首次描述。
Photolyase is a DNA repair enzyme that reverses UV-induced photoproducts in DNA in a light-dependent manner. Recently, photolyase homologs were identified in higher eukaryotes. These homologs, termed crypto-chromes, function as blue light photoreceptors or regulators of circadian rhythm. In contrast, most bacteria have only a single photolyase or photolyase-like gene. Unlike other microbes, the chromosome of the cyanobacterium Synechocystis sp, PCC6803 contains two ORFs (slr0854 and sll1629) with-high similarities to photolyases. We have characterized both genes. The slr0854 gene product exhibited specific, light-dependent repair activity for a cyclobutane pyrimidine dimer (CPD), whereas the sll1629 gene product lacks measurable affinity for DNA in vitro. Disruption of either slr0854 or sll1629 had little or no effect on the growth rate of the cyanobacterium. A mutant lacking the slr0854 gene showed severe UV sensitivity, in contrast to a mutant lacking sll1629, Phylogenetic analysis showed that sll1629 is more closely related to the cryptochromes than photolyases. We conclude that sll1629 is a bacterial cryptochrome. To our knowledge, this is the first description of a bacterial cryptochrome.