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Báo cáo khoa học: Plant DNA polymerase k, a DNA repair enzyme that functions in plant meristematic and meiotic tissues

Little is known about the functions of DNA polymerasek (Pol k) recently identified in mammals. From the genomic sequence information of rice andArabidopsis, we found that Polkmay be the only member of the X-family in higher plants. We have succeeded in isolating the cDNA and recombinant protein of Polkin a higher plant, rice (Oryza sativaL. cv. Nipponbare) (OsPolk). OsPolkhad activities of DNA polymerase, terminal deoxyribonucleotidyl trans-ferase and deoxyribose phosphate lyase, a marker enzyme for base excision repair. . | Eur. J. Biochem. 271 2799-2807 2004 FEBS 2004 doi 10.1111 j.1432-1033.2004.04214.x Plant DNA polymerase k a DNA repair enzyme that functions in plant meristematic and meiotic tissues Yukinobu Uchiyama Seisuke Kimura Taichi Yamamoto Toyotaka Ishibashi and Kengo Sakaguchi Department of Applied Biological Science Faculty of Science and Technology Tokyo University of Science Japan Little is known about the functions of DNA polymerase k Pol k recently identified in mammals. From the genomic sequence information of rice and Arabidopsis we found that Pol k may be the only member of the X-family in higher plants. We have succeeded in isolating the cDNA and recombinant protein of Pol k in a higher plant rice Oryza sativa L. cv. Nipponbare OsPol k . OsPol k had activities of DNA polymerase terminal deoxyribonucleotidyl transferase and deoxyribose phosphate lyase a marker enzyme for base excision repair. It also interacted with rice proliferating cell nuclear antigen OsPCNA in a pull-down assay. OsPCNA increased the processivity of OsPol k. Northern blot analysis showed that the level of OsPol k expression correlated with cell proliferation in meristematic and meiotic tissues and was induced by DNA-damaging treatments. These properties suggest that plant Pol k is a DNA repair enzyme which functions in plant meristematic and meiotic tissues and that it can substitute for Pol b and terminal deoxyribonucleotidyl transferase. Keywords deoxyribose phosphate lyase DNA polymerase DNA repair enzyme terminal deoxyribonucleotidyl transferase. Ten years ago only five DNA polymerase species a to e were known and the in vivo roles of each enzyme were thought to have been mostly deciphered. Thanks to the progress of the genome project however the story has now greatly changed. To date at least 15 classes of DNA polymerase have been identified in animals i.e. Pol a b c Ỗ e f g ỡ í K k I V r and terminal deoxyribonucleotidyl transferase TdT and based on their properties the polymerases are .