Molecular cloning and functional expression of a human cDNA encoding the antimutator enzyme 8-hydroxyguanine-DNA glycosylase.
The major mutagenic base lesion in DNA caused by exposure to reactive oxygen species is 8-hydroxyguanine (8-oxo-7, 8-dihydroguanine). In bacteria and Saccharomyces cerevisiae, this damaged base is excised by a DNA glycosylase with an associated lyase activity for chain cleavage. We have cloned, sequenced, and expressed a human cDNA with partial sequence homology to the relevant yeast gene. The encoded 47-kDa human enzyme releases free 8-hydroxyguanine from oxidized DNA and introduces a chain break in a double-stranded oligonucleotide specifically at an 8-hydroxyguanine residue base paired with cytosine. Expression of the human protein in a DNA repair-deficient E. coli mutM mutY strain partly suppresses its spontaneous mutator phenotype. The gene encoding the human enzyme maps to chromosome 3p25. These results show that human cells have an enzyme that can initiate base excision repair at mutagenic DNA lesions caused by active oxygen.
Roldán-Arjona
T
T
Imperial Cancer Research Fund, Clare Hall Laboratories, South Mimms, Hertfordshire, EN6 3LD, United Kingdom.
Wei
Y F
YF
Carter
K C
KC
Klungland
A
A
Anselmino
C
C
Wang
R P
RP
Augustus
M
M
Lindahl
T
T
D000595:Amino Acid Sequence; D002874:Chromosome Mapping; D002893:Chromosomes, Human, Pair 3; D003001:Cloning, Molecular; D045647:DNA Glycosylases; D018076:DNA, Complementary; D043382:DNA-Formamidopyrimidine Glycosylase; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D006801:Humans; D008969:Molecular Sequence Data; D009699:N-Glycosyl Hydrolases / Q000235:genetics* / Q000302:isolation & purification / Q000378:metabolism; D010641:Phenotype; D017386:Sequence Homology, Amino Acid; D013379:Substrate Specificity
D018076:DNA, Complementary; D029968:Escherichia coli Proteins; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C061738:mutY adenine glycosylase; D043382:DNA-Formamidopyrimidine Glycosylase; C468610:DNA-formamidopyrimidine glycosylase, E coli