Generation and elimination of 8-oxo-7,8-dihydro-2'-deoxyguanosine 5'-triphosphate, a mutagenic substrate for DNA synthesis, in human cells. 1995

H Hayakawa, and A Taketomi, and K Sakumi, and M Kuwano, and M Sekiguchi
Department of Biochemistry, Faculty of Medicine, Kyushu University, Fukuoka, Japan.

8-Oxo-7,8-dihydro-2'-deoxyguanosine 5'-triphosphate (8-oxo-dGTP) is a potent mutagenic substrate for DNA synthesis. The present study deals with generation and degradation of 8-oxo-dGTP in the nucleotide pool of human cells. (1) 8-Oxo-dGTP can be generated not only by direct oxidation of dGTP but also by phosphorylation of 8-oxo-dGDP by nucleoside diphosphate kinase. (2) 8-Oxo-dGTP is rapidly degraded to 8-oxo-dGMP by cellular 8-oxo-dGTPase activity. 8-Oxo-dGMP thus produced cannot be rephosphorylated; guanylate kinase, which phosphorylates both GMP and dGMP to the corresponding nucleoside diphosphates, is totally inactive for 8-oxo-dGMP. (3) 8-Oxo-dGMP is further degraded to 8-oxo-deoxyguanosine by a nucleotidase. The enzyme was partially purified from an extract of human Jurkat cells, and the mode of action was elucidated. 8-Oxo-dGMP is the most preferred substrate of the enzyme, and other nucleoside monophosphates are cleaved at significantly lower rates: Km for 8-oxo-dGMP is 10 times lower than that for dGMP, the second best substrate for the enzyme. The enzyme appears to convert 8-oxo-dGMP, which accumulates in the cellular nucleotide pool, to a form readily excretable to the cell exterior.

UI MeSH Term Description Entries
D009153 Mutagens Chemical agents that increase the rate of genetic mutation by interfering with the function of nucleic acids. A clastogen is a specific mutagen that causes breaks in chromosomes. Clastogen,Clastogens,Genotoxin,Genotoxins,Mutagen
D009701 Nucleoside-Diphosphate Kinase An enzyme that is found in mitochondria and in the soluble cytoplasm of cells. It catalyzes reversible reactions of a nucleoside triphosphate, e.g., ATP, with a nucleoside diphosphate, e.g., UDP, to form ADP and UTP. Many nucleoside diphosphates can act as acceptor, while many ribo- and deoxyribonucleoside triphosphates can act as donor. EC 2.7.4.6. Deoxynucleoside Diphosphate Kinases,GDP Kinase,Nucleoside Diphosphokinases,Nucleoside-Diphosphate Kinases,Diphosphate Kinases, Deoxynucleoside,Diphosphokinases, Nucleoside,Kinase, GDP,Kinase, Nucleoside-Diphosphate,Kinases, Deoxynucleoside Diphosphate,Kinases, Nucleoside-Diphosphate,Nucleoside Diphosphate Kinase,Nucleoside Diphosphate Kinases
D009703 Nucleoside-Phosphate Kinase An enzyme that catalyzes reversible reactions of a nucleoside triphosphate, e.g., ATP, with a nucleoside monophosphate, e.g., UMP, to form ADP and UDP. Many nucleoside monophosphates can act as acceptor while many ribo- and deoxyribonucleoside triphosphates can act as donor. EC 2.7.4.4. Nucleoside Monophosphate Kinases,Kinase, Nucleoside-Phosphate,Kinases, Nucleoside Monophosphate,Monophosphate Kinases, Nucleoside,Nucleoside Phosphate Kinase
D009708 Nucleotidases A class of enzymes that catalyze the conversion of a nucleotide and water to a nucleoside and orthophosphate. EC 3.1.3.-.
D010766 Phosphorylation The introduction of a phosphoryl group into a compound through the formation of an ester bond between the compound and a phosphorus moiety. Phosphorylations
D002474 Cell-Free System A fractionated cell extract that maintains a biological function. A subcellular fraction isolated by ultracentrifugation or other separation techniques must first be isolated so that a process can be studied free from all of the complex side reactions that occur in a cell. The cell-free system is therefore widely used in cell biology. (From Alberts et al., Molecular Biology of the Cell, 2d ed, p166) Cellfree System,Cell Free System,Cell-Free Systems,Cellfree Systems,System, Cell-Free,System, Cellfree,Systems, Cell-Free,Systems, Cellfree
D003848 Deoxyguanine Nucleotides Guanine nucleotides which contain deoxyribose as the sugar moiety. Deoxyguanosine Phosphates,Nucleotides, Deoxyguanine,Phosphates, Deoxyguanosine
D004247 DNA A deoxyribonucleotide polymer that is the primary genetic material of all cells. Eukaryotic and prokaryotic organisms normally contain DNA in a double-stranded state, yet several important biological processes transiently involve single-stranded regions. DNA, which consists of a polysugar-phosphate backbone possessing projections of purines (adenine and guanine) and pyrimidines (thymine and cytosine), forms a double helix that is held together by hydrogen bonds between these purines and pyrimidines (adenine to thymine and guanine to cytosine). DNA, Double-Stranded,Deoxyribonucleic Acid,ds-DNA,DNA, Double Stranded,Double-Stranded DNA,ds DNA
D006801 Humans Members of the species Homo sapiens. Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D013379 Substrate Specificity A characteristic feature of enzyme activity in relation to the kind of substrate on which the enzyme or catalytic molecule reacts. Specificities, Substrate,Specificity, Substrate,Substrate Specificities

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