Jaruga Pawel, Jabil Ritche, McCullough Amanda K, Rodriguez Henry, Dizdaroglu Miral, Lloyd R Stephen
Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA.
Photochem Photobiol. 2002 Feb;75(2):85-91. doi: 10.1562/0031-8655(2002)075<0085:cvpdge>2.0.co;2.
A DNA glycosylase specific for UV radiation-induced pyrimidine dimers has been identified from the Chlorella virus Paramecium Bursaria Chlorella virus-1. This enzyme (Chlorella virus pyrimidine dimer glycosylase [cv-pdg]) exhibits a 41% amino acid identity with endonuclease V from bacteriophage T4 (T4 pyrimidine dimer glycosylase [T4-pdg]), which is also specific for pyrimidine dimers. However, cv-pdg possesses a higher catalytic efficiency and broader substrate specificity than T4-pdg. The latter excises 4,6-diamino-5-formamidopyrimidine (FapyAde), a UV radiation- and hydroxyl radical-induced monomeric product of adenine in DNA. Using gas chromatography-isotope-dilution mass spectrometry and y-irradiated DNA, we show in this work that cv-pdg also displays a catalytic activity for excision of FapyAde and, in addition, it excises 2,6-diamino-4-hydroxy-5-formamidopyrimidine (FapyGua). Kinetic data show that FapyAde is a better substrate for cv-pdg than FapyGua. On the other hand, cv-pdg possesses a greater efficiency for the extension of FapyAde than T4-pdg. These two enzymes exhibit different substrate specificities despite substantial structural similarities.
从草履虫小球藻病毒1（Paramecium Bursaria Chlorella virus-1）中鉴定出一种对紫外线辐射诱导的嘧啶二聚体具有特异性的DNA糖基化酶。这种酶（小球藻病毒嘧啶二聚体糖基化酶[cv-pdg]）与噬菌体T4的内切核酸酶V（T4嘧啶二聚体糖基化酶[T4-pdg]）具有41%的氨基酸同一性，后者也对嘧啶二聚体具有特异性。然而，cv-pdg比T4-pdg具有更高的催化效率和更广泛的底物特异性。T4-pdg能切除4,6-二氨基-5-甲酰胺基嘧啶（FapyAde），这是DNA中腺嘌呤的紫外线辐射和羟基自由基诱导的单体产物。在这项工作中，我们使用气相色谱-同位素稀释质谱法和γ射线辐照的DNA表明，cv-pdg对FapyAde的切除也具有催化活性，此外，它还能切除2,6-二氨基-4-羟基-5-甲酰胺基嘧啶（FapyGua）。动力学数据表明，FapyAde是cv-pdg比FapyGua更好的底物。另一方面，cv-pdg对FapyAde的延伸效率比T4-pdg更高。尽管这两种酶在结构上有很大相似性，但它们表现出不同的底物特异性。
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