title: Ribonucleotide reductase association with mammalian liver mitochondria.
abstract: Deoxyribonucleoside triphosphate pools in mammalian mitochondria are highly asymmetric, and this asymmetry probably contributes to the elevated mutation rate for the mitochondrial genome as compared with the nuclear genome. To understand this asymmetry, we must identify pathways for synthesis and accumulation of dNTPs within mitochondria. We have identified ribonucleotide reductase activity specifically associated with mammalian tissue mitochondria. Examination of immunoprecipitated proteins by mass spectrometry revealed R1, the large ribonucleotide reductase subunit, in purified mitochondria. Significant enzymatic and immunological activity was seen in rat liver mitochondrial nucleoids, isolated as described by Wang and Bogenhagen (Wang, Y., and Bogenhagen, D. F. (2006) J. Biol. Chem. 281, 25791-25802). Moreover, incubation of respiring rat liver mitochondria with [(14)C]cytidine diphosphate leads to accumulation of radiolabeled deoxycytidine and thymidine nucleotides within the mitochondria. Comparable results were seen with [(14)C]guanosine diphosphate. Ribonucleotide reduction within the mitochondrion, as well as outside the organelle, needs to be considered as a possibly significant contributor to mitochondrial dNTP pools.
authors.affiliation: Department of Biochemistry and Biophysics, Oregon State University, Corvallis, Oregon 97331-7305, USA.
authors.forename: Korakod
authors.initials: K
authors.lastname: Chimploy
authors.forename: Shiwei
authors.initials: S
authors.lastname: Song
authors.forename: Linda J
authors.initials: LJ
authors.lastname: Wheeler
authors.forename: Christopher K
authors.initials: CK
authors.lastname: Mathews
mesh_terms: D000818:Animals; D020134:Catalytic Domain / Q000502:physiology; D003854:Deoxyribonucleotides / Q000378:metabolism*; D008930:Mitochondria, Liver / Q000201:enzymology*; D024101:Mitochondrial Proteins / Q000378:metabolism*; D051381:Rats; D012264:Ribonucleotide Reductases / Q000378:metabolism*
chemical_list: D003854:Deoxyribonucleotides; D024101:Mitochondrial Proteins; D012264:Ribonucleotide Reductases
keywords: DNA Precursors; Mitochondria; Mitochondrial DNA; Nucleoside Nucleotide Metabolism; Nucleotide; Ribonucleotide Reductase; dNTP Synthesis