紫外线C对聚球藻属PCC 7942光解酶结构和功能的影响

Influence of ultraviolet-C on structure and function of Synechococcus sp. PCC 7942 photolyase.

作者信息

Zhang L W, Li M, Wu Q Y

机构信息

Department of Biological Sciences and Biotechnology, Tsinghua University, Beijing, 100084, P. R. China.

出版信息

Biochemistry (Mosc). 2007 May;72(5):540-4. doi: 10.1134/s0006297907050100.

DOI:10.1134/s0006297907050100

PMID:17573708

Abstract

In this work, an over-expressed cyclobutane pyrimidine dimer (CPD) photolyase of Synechococcus sp. PCC 7942 was used to investigate UV-C (ultraviolet irradiation of C-region) influence on photoreactivation. In vivo photoreactivation experiments indicated that the survival rate decreased from 100 to 2.6% when the UV-C flux was increased from 1.1 to 68.5 muW/cm2. It seemed that the photolyase was easily inactivated at UV-C intensities >or=25.5 muW/cm2. Spectrometric analysis indicated that tertiary structure of the photolyase changed evidently when the UV-C fluxes were >or=25.5 muW/cm2, while the secondary structure was almost unchanged even at 170 muW/cm2. Band shift assay indicated that catalytic activity of the photolyase was impaired at fluxes >or=25.5 muW/cm2, but no significant influence on DNA-binding activity was observed. These results suggest that photoreactivation is efficient at UV-C fluxes <or=25.5 muW/cm2, but would be impaired by intense UV-C irradiation due to structure changes of the photolyase.

摘要

在本研究中，使用来自聚球藻属PCC 7942的过表达环丁烷嘧啶二聚体（CPD）光解酶来研究UV-C（C波段紫外线照射）对光复活作用的影响。体内光复活实验表明，当UV-C通量从1.1增加到68.5 μW/cm²时，存活率从100%降至2.6%。似乎在UV-C强度≥25.5 μW/cm²时，光解酶很容易失活。光谱分析表明，当UV-C通量≥25.5 μW/cm²时，光解酶的三级结构发生明显变化，而即使在170 μW/cm²时，其二级结构几乎没有变化。凝胶迁移实验表明，在通量≥25.5 μW/cm²时，光解酶的催化活性受到损害，但未观察到对DNA结合活性有显著影响。这些结果表明，在UV-C通量≤25.5 μW/cm²时光复活作用有效，但由于光解酶结构变化，强烈的UV-C照射会损害光复活作用。