Characterization of 2-hydroxyadenine DNA glycosylase activity of Escherichia coli MutY protein.
OBJECTIVE
2-Hydroxyadenine (2-ohA) is an oxidation product of adenine generated in DNA by ionizing radiation and various chemical oxidants. 2-ohA has mutational potential comparable to that of 8-oxoguanine in bacteria and mammalian cells. Recent studies have shown that 2-ohA is removed from DNA by a human MutY homolog, MYH protein, in vitro. On the other hand, the repair mechanisms for 2-ohA in Escherichia coli are not yet understood.


METHODS
Gel shift assays were used to assess the binding activity of E. coli full-length MutY protein and its N-terminal (residues 1-226) domain (M25) to 2-ohA/G-, 2-ohA/A-, 2-ohA/C- and 2-ohA/T-containing 24-mer oligonucleotides. Furthermore, whether these proteins specifically cleave 2-ohA-containing duplex oligonucleotides was examined.


RESULTS
The purified MutY and M25 proteins had similar binding affinities to 2-ohA/G-, 2-ohA/A- and 2-ohA/C-containing oligonucleotides. MutY protein removed 2-ohA preferentially from 2-ohA/G mispairs. M25 protein showed the reduced catalytic activity for 2-ohA/G-containing oligonucleotides.


CONCLUSIONS
E. coli MutY protein has a DNA glycosylase activity that removes 2-ohA from 2-ohA/G mispairs in DNA. The C-terminal domain is required for the removal of 2-ohA from DNA, but is not crucial for binding to 2-ohA-containing oligonucleotides.
Hashiguchi
K
K
Laboratory for Radiation Biology, Graduate School of Science, Kyoto University, Kitashirakawa-Oiwakecho, Sakyoku, Kyoto 606-8502, Japan.
Zhang
Q M
QM
Sugiyama
H
H
Ikeda
S
S
Yonei
S
S
D004247:DNA / Q000528:radiation effects; D004249:DNA Damage; D045647:DNA Glycosylases; D004261:DNA Replication; D004926:Escherichia coli / Q000201:enzymology*; D009699:N-Glycosyl Hydrolases / Q000737:chemistry / Q000378:metabolism*; D009841:Oligonucleotides / Q000378:metabolism
D009841:Oligonucleotides; D004247:DNA; D045647:DNA Glycosylases; D009699:N-Glycosyl Hydrolases; C061738:mutY adenine glycosylase