Chlorella virus pyrimidine dimer glycosylase excises ultraviolet radiation- and hydroxyl radical-induced products 4,6-diamino-5-formamidopyrimidine and 2,6-diamino-4-hydroxy-5-formamidopyrimidine from DNA.
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.
Jaruga
Pawel
P
Chemical Science and Technology Laboratory, National Institute of Standards and Technology, Gaithersburg, MD, USA.
Jabil
Ritche
R
McCullough
Amanda K
AK
Rodriguez
Henry
H
Dizdaroglu
Miral
M
Lloyd
R Stephen
RS
D002708:Chlorella / Q000201:enzymology; D004249:DNA Damage; D045647:DNA Glycosylases; D004260:DNA Repair; D017665:Hydroxyl Radical / Q000009:adverse effects; D009699:N-Glycosyl Hydrolases / Q000235:genetics / Q000378:metabolism*; D011740:Pyrimidine Dimers / Q000378:metabolism*; D011743:Pyrimidines / Q000378:metabolism; D013379:Substrate Specificity; D014466:Ultraviolet Rays / Q000009:adverse effects
D011740:Pyrimidine Dimers; D011743:Pyrimidines; C071023:2,6-diamino-4-hydroxy-5-formamidopyrimidine; D017665:Hydroxyl Radical; C039544:4,6-diamino-5-N-formamidopyrimidine; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C036401:deoxyribopyrimidine endonucleosidase