Abstract
8-Oxoguanine (8-oxoG), induced by reactive oxygen species (ROS) and ionizing radiation, is arguably the most important mutagenic lesion in DNA. This oxidized base, because of its mispairing with A, induces GC→TA transversion mutations often observed spontaneously in tumor cells. The human cDNA encoding the repair enzyme 8-oxoG-DNA glycosylase (OGG-1) has recently been cloned, however, its activity was never detected in cells. Here we show that the apparent lack of this activity could be due to the presence of an 8-oxoG-specific DNA binding protein. Moreover, we demonstrate the presence of two antigenically distinct OGG activities with an identical reaction mechanism in human cell (HeLa) extracts. The 38 kDa OGG-1, identical to the cloned enzyme, cleaves 8-oxoG when paired with cytosine, thymine and guanine but not adenine in DNA. In contrast, the newly discovered 36 kDa OGG-2 prefers 8-oxoG paired with G and A. We propose that OGG-1 and OGG-2 have distinct antimutagenic functions in vivo. OGG-1 prevents mutation by removing 8-oxoG formed in DNA in situ and paired with C, while OGG-2 removes 8-oxoG that is incorporated opposite A in DNA from ROS-induced 8-oxodGTP. We predict that OGG-2 specifically removes such 8-oxoG residues only from the nascent strand, possibly by utilizing the same mechanism as the DNA mismatch repair pathway.
| Original language | English (US) |
|---|---|
| Pages (from-to) | 5116-5122 |
| Number of pages | 7 |
| Journal | Nucleic Acids Research |
| Volume | 26 |
| Issue number | 22 |
| State | Published - Nov 15 1998 |
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ASJC Scopus subject areas
- Genetics
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The presence of two distinct 8-oxoguanine repair enzymes in human cells : Their potential complementary roles in preventing mutation. / Hazra, Tapas; Izumi, Tadahide; Maidt, Lindsay; Floyd, Robert A.; Mitra, Sankar.
In: Nucleic Acids Research, Vol. 26, No. 22, 15.11.1998, p. 5116-5122.Research output: Contribution to journal › Article
}
TY - JOUR
T1 - The presence of two distinct 8-oxoguanine repair enzymes in human cells
T2 - Their potential complementary roles in preventing mutation
AU - Hazra, Tapas
AU - Izumi, Tadahide
AU - Maidt, Lindsay
AU - Floyd, Robert A.
AU - Mitra, Sankar
PY - 1998/11/15
Y1 - 1998/11/15
N2 - 8-Oxoguanine (8-oxoG), induced by reactive oxygen species (ROS) and ionizing radiation, is arguably the most important mutagenic lesion in DNA. This oxidized base, because of its mispairing with A, induces GC→TA transversion mutations often observed spontaneously in tumor cells. The human cDNA encoding the repair enzyme 8-oxoG-DNA glycosylase (OGG-1) has recently been cloned, however, its activity was never detected in cells. Here we show that the apparent lack of this activity could be due to the presence of an 8-oxoG-specific DNA binding protein. Moreover, we demonstrate the presence of two antigenically distinct OGG activities with an identical reaction mechanism in human cell (HeLa) extracts. The 38 kDa OGG-1, identical to the cloned enzyme, cleaves 8-oxoG when paired with cytosine, thymine and guanine but not adenine in DNA. In contrast, the newly discovered 36 kDa OGG-2 prefers 8-oxoG paired with G and A. We propose that OGG-1 and OGG-2 have distinct antimutagenic functions in vivo. OGG-1 prevents mutation by removing 8-oxoG formed in DNA in situ and paired with C, while OGG-2 removes 8-oxoG that is incorporated opposite A in DNA from ROS-induced 8-oxodGTP. We predict that OGG-2 specifically removes such 8-oxoG residues only from the nascent strand, possibly by utilizing the same mechanism as the DNA mismatch repair pathway.
AB - 8-Oxoguanine (8-oxoG), induced by reactive oxygen species (ROS) and ionizing radiation, is arguably the most important mutagenic lesion in DNA. This oxidized base, because of its mispairing with A, induces GC→TA transversion mutations often observed spontaneously in tumor cells. The human cDNA encoding the repair enzyme 8-oxoG-DNA glycosylase (OGG-1) has recently been cloned, however, its activity was never detected in cells. Here we show that the apparent lack of this activity could be due to the presence of an 8-oxoG-specific DNA binding protein. Moreover, we demonstrate the presence of two antigenically distinct OGG activities with an identical reaction mechanism in human cell (HeLa) extracts. The 38 kDa OGG-1, identical to the cloned enzyme, cleaves 8-oxoG when paired with cytosine, thymine and guanine but not adenine in DNA. In contrast, the newly discovered 36 kDa OGG-2 prefers 8-oxoG paired with G and A. We propose that OGG-1 and OGG-2 have distinct antimutagenic functions in vivo. OGG-1 prevents mutation by removing 8-oxoG formed in DNA in situ and paired with C, while OGG-2 removes 8-oxoG that is incorporated opposite A in DNA from ROS-induced 8-oxodGTP. We predict that OGG-2 specifically removes such 8-oxoG residues only from the nascent strand, possibly by utilizing the same mechanism as the DNA mismatch repair pathway.
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M3 - Article
C2 - 9801308
AN - SCOPUS:0032533794
VL - 26
SP - 5116
EP - 5122
JO - Nucleic Acids Research
JF - Nucleic Acids Research
SN - 0305-1048
IS - 22
ER -