Abstract
We utilized a custom-synthesized double-strand oligonucleotide containing a single O6-methylguanine (O6-MG) residue within a restriction endonuclease recognition site to determine O6-methylguanine-DNA-methyltransferase (O6-MGMT) activity in various tissue extracts prepared from Xiphophorus fish. The results suggest Xiphophorus fish O6-MGMT activity has many of the same characteristics as Escherichia coli and mammalian O6-MGMT's including rapid reaction kinetics consistent with stoichiometric removal of methyl groups, but exhibits a temperature optimum of 23°C. Results from protein extract activity assays indicate O6-MGMT activity patterns among four Xiphophorus tissues followed the order: brain ≥ testes > gill ≥ liver. In mammals, O6-MGMT activity is high in liver, while activity in brain is minimal (i.e. ≈9% of liver); however, we report that in the Xiphophorus fishes examined, brain tissue extracts exhibited much higher (≈six-fold) O6-MGMT activity levels than liver. Comparison of O6-MGMT activity between Xiphophorus species employed in tumor induction experiments did not indicate significant differences in ability to clear the pre-mutagenic O6-MG from the oligonucleotide substrate.
| Original language | English |
|---|---|
| Pages (from-to) | 11-22 |
| Number of pages | 12 |
| Journal | Mutation Research - Genetic Toxicology and Environmental Mutagenesis |
| Volume | 493 |
| Issue number | 1-2 |
| DOIs | |
| Publication status | Published - 2001 Jun 27 |
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All Science Journal Classification (ASJC) codes
- Genetics
- Health, Toxicology and Mutagenesis
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Characterization of O6-methylguanine-DNA-methyltransferase (O6-MGMT) activity in Xiphophorus fishes. / Walter, Ronald B.; Sung, Huang-Mo; Intano, Gabe W.; Walter, Christi A.
In: Mutation Research - Genetic Toxicology and Environmental Mutagenesis, Vol. 493, No. 1-2, 27.06.2001, p. 11-22.Research output: Contribution to journal › Article
TY - JOUR
T1 - Characterization of O6-methylguanine-DNA-methyltransferase (O6-MGMT) activity in Xiphophorus fishes
AU - Walter, Ronald B.
AU - Sung, Huang-Mo
AU - Intano, Gabe W.
AU - Walter, Christi A.
PY - 2001/6/27
Y1 - 2001/6/27
N2 - We utilized a custom-synthesized double-strand oligonucleotide containing a single O6-methylguanine (O6-MG) residue within a restriction endonuclease recognition site to determine O6-methylguanine-DNA-methyltransferase (O6-MGMT) activity in various tissue extracts prepared from Xiphophorus fish. The results suggest Xiphophorus fish O6-MGMT activity has many of the same characteristics as Escherichia coli and mammalian O6-MGMT's including rapid reaction kinetics consistent with stoichiometric removal of methyl groups, but exhibits a temperature optimum of 23°C. Results from protein extract activity assays indicate O6-MGMT activity patterns among four Xiphophorus tissues followed the order: brain ≥ testes > gill ≥ liver. In mammals, O6-MGMT activity is high in liver, while activity in brain is minimal (i.e. ≈9% of liver); however, we report that in the Xiphophorus fishes examined, brain tissue extracts exhibited much higher (≈six-fold) O6-MGMT activity levels than liver. Comparison of O6-MGMT activity between Xiphophorus species employed in tumor induction experiments did not indicate significant differences in ability to clear the pre-mutagenic O6-MG from the oligonucleotide substrate.
AB - We utilized a custom-synthesized double-strand oligonucleotide containing a single O6-methylguanine (O6-MG) residue within a restriction endonuclease recognition site to determine O6-methylguanine-DNA-methyltransferase (O6-MGMT) activity in various tissue extracts prepared from Xiphophorus fish. The results suggest Xiphophorus fish O6-MGMT activity has many of the same characteristics as Escherichia coli and mammalian O6-MGMT's including rapid reaction kinetics consistent with stoichiometric removal of methyl groups, but exhibits a temperature optimum of 23°C. Results from protein extract activity assays indicate O6-MGMT activity patterns among four Xiphophorus tissues followed the order: brain ≥ testes > gill ≥ liver. In mammals, O6-MGMT activity is high in liver, while activity in brain is minimal (i.e. ≈9% of liver); however, we report that in the Xiphophorus fishes examined, brain tissue extracts exhibited much higher (≈six-fold) O6-MGMT activity levels than liver. Comparison of O6-MGMT activity between Xiphophorus species employed in tumor induction experiments did not indicate significant differences in ability to clear the pre-mutagenic O6-MG from the oligonucleotide substrate.
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U2 - 10.1016/S1383-5718(01)00169-3
DO - 10.1016/S1383-5718(01)00169-3
M3 - Article
VL - 493
SP - 11
EP - 22
JO - Mutation Research - Genetic Toxicology and Environmental Mutagenesis
JF - Mutation Research - Genetic Toxicology and Environmental Mutagenesis
SN - 1383-5718
IS - 1-2
ER -