Mouse MTH1 Protein with 8-Oxo-7,8-dihydro-2′-deoxyguanosine 5′-Triphosphatase Activity That Prevents Transversion Mutation

doi:10.1074/jbc.270.43.25942

Mouse MTH1 Protein with 8-Oxo-7,8-dihydro-2′-deoxyguanosine 5′-Triphosphatase Activity That Prevents Transversion Mutation

cDNA CLONING AND TISSUE DISTRIBUTION (*)

From the Department of Biochemistry, Medical Institute of Bioregulation, Kyushu University, Fukuoka 812-82, Japan

^§ To whom correspondence should be addressed. Tel.: 81-92-641-1151 (ext. 3731); Fax: 81-92-633-6801.

Abstract

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.

Footnotes

↵* This work was supported by grants from the Ministry of Education, Science and Culture of Japan and funding from the Human Frontier Science Program and from the Fukuoka Cancer Association. The costs of publication of this article were defrayed in part by the payment of page charges. This article must therefore by hereby marked “advertisement” in accordance with 18 U.S.C. Section 1734 solely to indicate this fact.

The nucleotide sequence(s) reported in this paper has been submitted to the GenBank™/EMBL Data Bank with accession number(s) D49956 [GenBank]
↵¹ The abbreviations used are:

8-oxoguanine

8-oxo-7,8-dihydroguanine

8-oxo-dGTP

8-oxo-7,8-dihydro-2′-deoxyguanosine 5′-triphosphate

8-oxo-dGTPase

8-oxo-7,8-dihydro-2′-deoxyguanosine triphosphatase

IAP

intracisternal A particle

IPTG

isopropyl-β-D-thiogalactopyranoside

BSA

bovine serum albumin

bp

base pair(s).
- Received May 8, 1995.
- Revision received August 16, 1995.