M. Sandigursky et Wa. Franklin, Thermostable uracil-DNA glycosylase from Thermotoga maritima, a member of a novel class of DNA repair enzymes, CURR BIOL, 9(10), 1999, pp. 531-534
Uracil-DNA glycosylase (UDG) is a ubiquitous enzyme found in eukaryotes and
prokaryotes [1-3]. This enzyme removes uracil bases that are present in DN
A as a result of either deamination of cytosine or misincorporation of dUMP
instead of dTMP [4,5], and it is the primary activity in the DNA base exci
sion repair pathway. Although UDG activities have been shown to be present
in several thermophiles [6-8], no sequences have been found that are comple
mentary to the Escherichia coli ung gene, which encodes UDG [9]. Here, we d
escribe a UDG from the thermophile Thermotoga maritima. The T.maritima UDG
gene has a low level of homology to the E.coli G-T/U mismatch-specific DNA
glycosylase gene (mug). The expressed protein is capable of removing uracil
from DNA containing either a U-A or a U-G base pair and is heat stable up
to 75 degrees C. The enzyme is also active on single-stranded DNA containin
g uracil. Analogous genes appear to be present in several prokaryotic organ
isms, including thermophilic and mesophilic eubacteria as well as archaebac
teria, the human-disease pathogens Treponema palladium and Rickettsia prowa
zekii, and the extremely radioresistant organism Deinococcus radiodurans. T
hese findings suggest that the T. maritima UDG is a member of a new class o
f DNA repair enzymes. (C) Elsevier Science Ltd ISSN 0960-9822.