期刊名称：Proceedings of the National Academy of Sciences
印刷版ISSN：0027-8424
电子版ISSN：1091-6490
出版年度：2001
卷号：98
期号：24
页码：13560-13565
DOI：10.1073/pnas.241371398
语种：English
出版社：The National Academy of Sciences of the United States of America
摘要：DNA photolyase is a pyrimidine-dimer repair enzyme that uses visible light. Photolyase generally contains two chromophore cofactors. One is a catalytic cofactor directly contributing to the repair of a pyrimidine-dimer. The other is a light-harvesting cofactor, which absorbs visible light and transfers energy to the catalytic cofactor. Photolyases are classified according to their second cofactor into either a folate- or deazaflavin-type. The native structures of both types of photolyases have already been determined, but the mechanism of substrate recognition remains largely unclear because of the lack of structural information regarding the photolyase-substrate complex. Photolyase from Thermus thermophilus, the first thermostable class I photolyase found, is favorable for function analysis, but even the type of the second cofactor has not been identified. Here, we report the crystal structures of T. thermophilus photolyase in both forms of the native enzyme and the complex along with a part of its substrate, thymine. A structural comparison with other photolyases suggests that T. thermophilus photolyase has structural features allowing for thermostability and that its light-harvesting cofactor binding site bears a close resemblance to a deazaflavin-type photolyase. One thymine base is found at the hole, a putative substrate-binding site near the catalytic cofactor in the complex form. This structural data for the photolyase-thymine complex allow us to propose a detailed model for the pyrimidine-dimer recognition mechanism.
