Yasui A, McCready S J
Institute of Development, Aging and Cancer, Sendai, Japan.
Bioessays. 1998 Apr;20(4):291-7. doi: 10.1002/(SICI)1521-1878(199804)20:4<291::AID-BIES5>3.0.CO;2-T.
Ultraviolet light (UV) is thought to have had a major impact on the early evolution of life. UV is absorbed by nucleic acids and produces several types of DNA damage, which interfere with DNA replication and transcription. This damage can result in mutagenesis and cell killing. Several mechanisms for repairing UV-induced DNA damage have been identified. Besides the widely distributed nucleotide excision repair, two alternative repair mechanisms for specific lesions in UV-damaged DNA are known, involving photolyases and DNA glycosylases. Recently, a novel endonuclease for UV-induced DNA damage was identified that initiates an excision repair pathway completely different from previously established repair mechanisms. The finding of this "alternative excision repair" suggests the presence of a new category of DNA repair, initiated by single-strand breaks in DNA. Homologues of the UVDE enzyme have been found in eukaryotic microorganisms, as well as in bacteria, indicating that the enzyme originated early in evolution, and suggesting the existence of multirepair systems for UV-induced DNA damage during early evolution.
紫外线（UV）被认为对生命的早期进化产生了重大影响。核酸会吸收紫外线并产生多种类型的DNA损伤，这些损伤会干扰DNA复制和转录。这种损伤可能导致诱变和细胞死亡。已经确定了几种修复紫外线诱导的DNA损伤的机制。除了广泛分布的核苷酸切除修复外，已知紫外线损伤的DNA中特定损伤的两种替代修复机制，涉及光解酶和DNA糖基化酶。最近，发现了一种用于紫外线诱导的DNA损伤的新型核酸内切酶，它启动了一种与先前建立的修复机制完全不同的切除修复途径。这种“替代切除修复”的发现表明存在一种新的DNA修复类别，由DNA中的单链断裂引发。在真核微生物以及细菌中都发现了UVDE酶的同源物，这表明该酶在进化早期就已出现，并暗示在早期进化过程中存在针对紫外线诱导的DNA损伤的多修复系统。
