Biomaterial Database

Role of polynucleotide kinase/phosphatase in mitochondrial DNA repair. 2012

Nasser Tahbaz, and Sudip Subedi, and Michael Weinfeld

Department of Oncology, University of Alberta and Experimental Oncology, Cross Cancer Institute, 11560 University Avenue, Edmonton, Alberta, Canada, T6G 1Z2.

Mutations in mitochondrial DNA (mtDNA) are implicated in a broad range of human diseases and in aging. Compared to nuclear DNA, mtDNA is more highly exposed to oxidative damage due to its proximity to the respiratory chain and the lack of protection afforded by chromatin-associated proteins. While repair of oxidative damage to the bases in mtDNA through the base excision repair pathway has been well studied, the repair of oxidatively induced strand breaks in mtDNA has been less thoroughly examined. Polynucleotide kinase/phosphatase (PNKP) processes strand-break termini to render them chemically compatible for the subsequent action of DNA polymerases and ligases. Here, we demonstrate that functionally active full-length PNKP is present in mitochondria as well as nuclei. Downregulation of PNKP results in an accumulation of strand breaks in mtDNA of hydrogen peroxide-treated cells. Full restoration of repair of the H(2)O(2)-induced strand breaks in mitochondria requires both the kinase and phosphatase activities of PNKP. We also demonstrate that PNKP contains a mitochondrial-targeting signal close to the C-terminus of the protein. We further show that PNKP associates with the mitochondrial protein mitofilin. Interaction with mitofilin may serve to translocate PNKP into mitochondria.

UI	MeSH Term	Description	Entries
D008928	Mitochondria	Semiautonomous, self-reproducing organelles that occur in the cytoplasm of all cells of most, but not all, eukaryotes. Each mitochondrion is surrounded by a double limiting membrane. The inner membrane is highly invaginated, and its projections are called cristae. Mitochondria are the sites of the reactions of oxidative phosphorylation, which result in the formation of ATP. They contain distinctive RIBOSOMES, transfer RNAs (RNA, TRANSFER); AMINO ACYL T RNA SYNTHETASES; and elongation and termination factors. Mitochondria depend upon genes within the nucleus of the cells in which they reside for many essential messenger RNAs (RNA, MESSENGER). Mitochondria are believed to have arisen from aerobic bacteria that established a symbiotic relationship with primitive protoeukaryotes. (King & Stansfield, A Dictionary of Genetics, 4th ed)	Mitochondrial Contraction,Mitochondrion,Contraction, Mitochondrial,Contractions, Mitochondrial,Mitochondrial Contractions
D011116	Polynucleotide 5'-Hydroxyl-Kinase	An enzyme that catalyzes the transfer of a phosphate group to the 5'-terminal hydroxyl groups of DNA and RNA. EC 2.7.1.78.	Polynucleotide Hydroxylkinase,Polynucleotide Kinase,5'-Hydroxylpolynucleotide Kinase,DNA 5'-Hydroxylkinase,DNA Kinase,Polynucleotide 5'-Hydroxyl Kinase,Polynucleotide Hydroxykinase,5' Hydroxylpolynucleotide Kinase,5'-Hydroxyl Kinase, Polynucleotide,5'-Hydroxyl-Kinase, Polynucleotide,5'-Hydroxylkinase, DNA,DNA 5' Hydroxylkinase,Hydroxykinase, Polynucleotide,Hydroxylkinase, Polynucleotide,Kinase, 5'-Hydroxylpolynucleotide,Kinase, DNA,Kinase, Polynucleotide,Kinase, Polynucleotide 5'-Hydroxyl,Polynucleotide 5' Hydroxyl Kinase
D004260	DNA Repair	The removal of DNA LESIONS and/or restoration of intact DNA strands without BASE PAIR MISMATCHES, intrastrand or interstrand crosslinks, or discontinuities in the DNA sugar-phosphate backbones.	DNA Damage Response
D004272	DNA, Mitochondrial	Double-stranded DNA of MITOCHONDRIA. In eukaryotes, the mitochondrial GENOME is circular and codes for ribosomal RNAs, transfer RNAs, and about 10 proteins.	Mitochondrial DNA,mtDNA
D006801	Humans	Members of the species Homo sapiens.	Homo sapiens,Man (Taxonomy),Human,Man, Modern,Modern Man
D000818	Animals	Unicellular or multicellular, heterotrophic organisms, that have sensation and the power of voluntary movement. Under the older five kingdom paradigm, Animalia was one of the kingdoms. Under the modern three domain model, Animalia represents one of the many groups in the domain EUKARYOTA.	Animal,Metazoa,Animalia
D017208	Rats, Wistar	A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.	Wistar Rat,Rat, Wistar,Wistar Rats
D045744	Cell Line, Tumor	A cell line derived from cultured tumor cells.	Tumor Cell Line,Cell Lines, Tumor,Line, Tumor Cell,Lines, Tumor Cell,Tumor Cell Lines
D051381	Rats	The common name for the genus Rattus.	Rattus,Rats, Laboratory,Rats, Norway,Rattus norvegicus,Laboratory Rat,Laboratory Rats,Norway Rat,Norway Rats,Rat,Rat, Laboratory,Rat, Norway,norvegicus, Rattus
D021382	Protein Sorting Signals	Amino acid sequences found in transported proteins that selectively guide the distribution of the proteins to specific cellular compartments.	Leader Signal Peptides,Leader Peptide,Leader Sequences, Peptide,Peptide Leader Sequences,Peptide Signal Sequences,Signal Peptide,Signal Peptides,Signal Sequence, Peptide,Signal Sequences,Signal Sequences, Peptide,Leader Peptides,Leader Sequence, Peptide,Leader Signal Peptide,Peptide Leader Sequence,Peptide Signal Sequence,Peptide, Leader,Peptide, Leader Signal,Peptide, Signal,Peptides, Leader,Peptides, Leader Signal,Peptides, Signal,Protein Sorting Signal,Sequence, Peptide Leader,Sequence, Peptide Signal,Sequence, Signal,Sequences, Peptide Leader,Sequences, Peptide Signal,Sequences, Signal,Signal Peptide, Leader,Signal Peptides, Leader,Signal Sequence,Signal, Protein Sorting,Signals, Protein Sorting,Sorting Signal, Protein,Sorting Signals, Protein