Mouse MTH1 protein with 8-oxo-7,8-dihydro-2'-deoxyguanosine 5'-triphosphatase activity that prevents transversion mutation. cDNA cloning and tissue distribution.
8-Oxo-7,8-dihydro-2'-deoxyguanosine 5'-triphosphate (8-oxo-dGTP) is formed in the nucleotide pool of a cell during normal cellular metabolism, and when it is incorporated into DNA causes mutation. Organisms possess 8-oxo-dGTPase, an enzyme that specifically degrades 8-oxo-dGTP to 8-oxo-dGMP. We isolated cDNA for mouse 8-oxo-dGTPase, using as a probe human MTH1 (Escherichia coli mutT homolog) cDNA. The nucleotide sequence of the cDNA revealed that the mouse MTH1 protein (molecular weight of 17,896) comprises 156 amino acid residues. When the cDNA for mouse 8-oxo-dGTPase was expressed in E. coli mutT- mutant cells devoid of their own 8-oxo-dGTPase activity, an 18-kDa protein, which is cross-reactive with an anti-human MTH1 antibody, was formed. In such cells, the level of spontaneous mutation frequency that was elevated reverted to normal. High levels of 8-oxo-dGTPase activity were found in liver, thymus, and large intestine, whereas all other organs examined contained smaller amounts of the enzyme. In embryonic stem cells, an exceedingly high level of the enzyme was present.
Kakuma
T
T
Department of Biochemistry, Kyushu University, Fukuoka, Japan.
Nishida
J
J
Tsuzuki
T
T
Sekiguchi
M
M
D000595:Amino Acid Sequence; D000818:Animals; D016587:Antimutagenic Agents; D001426:Bacterial Proteins / Q000235:genetics; D001483:Base Sequence; D015152:Blotting, Northern; D045643:DNA Repair Enzymes; D018076:DNA, Complementary / Q000235:genetics; D003848:Deoxyguanine Nucleotides / Q000378:metabolism*; D004926:Escherichia coli / Q000235:genetics; D029968:Escherichia coli Proteins; D015723:Gene Library; D005816:Genetic Complementation Test; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D016296:Mutagenesis; D010744:Phosphoric Monoester Hydrolases / Q000235:genetics* / Q000276:immunology / Q000302:isolation & purification; D011233:Precipitin Tests; D011755:Pyrophosphatases; D011994:Recombinant Proteins / Q000276:immunology / Q000302:isolation & purification; D017386:Sequence Homology, Amino Acid; D013045:Species Specificity; D013489:Suppression, Genetic; D014018:Tissue Distribution
D016587:Antimutagenic Agents; D001426:Bacterial Proteins; D018076:DNA, Complementary; D003848:Deoxyguanine Nucleotides; D029968:Escherichia coli Proteins; D011994:Recombinant Proteins; C078206:8-oxodeoxyguanosine triphosphate; D010744:Phosphoric Monoester Hydrolases; D011755:Pyrophosphatases; C052211:mutT protein, E coli; C078207:8-oxodGTPase; D045643:DNA Repair Enzymes