Biochemical properties of a plastidial DNA polymerase of rice
- 223 Downloads
Plastids are organelles unique to plant cells and are responsible for photosynthesis and other metabolic functions. Despite their important cellular roles, relatively little is known about the mechanism of plastidial DNA replication and repair. Recently, we identified a novel DNA polymerase in Oryza Sativa L. (OsPOLP1, formerly termed OsPolI-like) that is homologous to prokaryotic DNA polymerase Is (PolIs), and suggested that this polymerase might be involved in plastidial DNA replication and repair. Here, we propose to rename the plant PolI homologs as DNA polymerase π (POLP), and investigate the biochemical properties of full-length OsPOLP1. The purified OsPOLP1 elongated both DNA and RNA primer hybridized to a DNA template, and possessed a 3′ exonuclease activity. Moreover, OsPOLP1 displayed high processivity and fidelity, indicating that this polymerase has the biochemical characteristics appropriate for DNA replication. We found that POLPs have two extra sequences in the polymerase domain that are absent in prokaryotic PolIs. Deletion of either insert from OsPOLP1 caused a decrease in DNA synthetic activity, processivity, and DNA binding activity. In addition, OsPOLP1 efficiently catalyzed strand displacement on nicked DNA with a 5′-deoxyribose phosphate, suggesting that this enzyme might be involved in a repair pathway similar to long-patch base excision repair. These results provide insights into the possible role of POLPs in plastidial DNA replication and repair.
KeywordsDNA polymerase π DNA repair DNA replication Oryza sativa L. Plastid Processivity
DNA polymerase π
- E. coli
Base excision repair
We thank Dr. Kei-ichi Takata (University of Pittsburgh Cancer Institute, Hillman Cancer Center, Research Pavilion, Pittsburgh, PA) for the helpful discussion of this work. R.T. and S.K. were supported by Research Fellowships of the Japan Society for the Promotion of Science.
- Bloom LB, Chen X, Fygenson DK, Turner J, O'Donnell M, Goodman MF (1997) Fidelity of Escherichia coli DNA polymerase III holoenzyme. The effects of β, γ complex processivity proteins and ε proofreading exonuclease on nucleotide misincorporation efficiencies. J Biol Chem 272:27919–27930PubMedCrossRefGoogle Scholar
- Burgers PM, Koonin EV, Bruford E, Blanco L, Burtis KC, Christman MF, Copeland WC, Friedberg EC, Hanaoka F, Hinkle DC, Lawrence CW, Nakanishi M, Ohmori H, Prakash L, Prakash S, Reynaud CA, Sugino A, Todo T, Wang Z, Weill JC, Woodgate R (2001) Eukaryotic DNA polymerases: proposal for a revised nomenclature. J Biol Chem 276:43487–43490PubMedCrossRefGoogle Scholar
- Kikuchi S, Satoh K, Nagata T, Kawagashira N, Doi K, Kishimoto N, Yazaki J, Ishikawa M, Yamada H, Ooka H, Hotta I, Kojima K, Namiki T, Ohneda E, Yahagi W, Suzuki K, Li CJ, Ohtsuki K, Shishiki T, Otomo Y, Murakami K, Iida Y, Sugano S, Fujimura T, Suzuki Y, Tsunoda Y, Kurosaki T, Kodama T, Masuda H, Kobayashi M, Xie Q, Lu M, Narikawa R, Sugiyama A, Mizuno K, Yokomizo S, Niikura J, Ikeda R, Ishibiki J, Kawamata M, Yoshimura A, Miura J, Kusumegi T, Oka M, Ryu R, Ueda M, Matsubara K, Kawai J, Carninci P, Adachi J, Aizawa K, Arakawa T, Fukuda S, Hara A, Hashizume W, Hayatsu N, Imotani K, Ishii Y, Itoh M, Kagawa I, Kondo S, Konno H, Miyazaki A, Osato N, Ota Y, Saito R, Sasaki D, Sato K, Shibata K, Shinagawa A, Shiraki T, Yoshino M, Hayashizaki Y, Yasunishi A (2003) Collection, mapping, and annotation of over 28,000 cDNA clones from japonica rice. Science 301:376–379PubMedCrossRefGoogle Scholar
- Kimura S, Uchiyama Y, Kasai N, Namekawa S, Saotome A, Ueda T, Ando T, Ishibashi T, Oshige M, Furukawa T, Yamamoto T, Hashimoto J, Sakaguchi K (2002) A novel DNA polymerase homologous to Escherichia coli DNA polymerase I from a higher plant, rice (Oryza sativa L.). Nucl Acids Res 30:1585–1592PubMedCrossRefGoogle Scholar
- Spelbrink JN, Li FY, Tiranti V, Nikali K, Yuan QP, Tariq M, Wanrooij S, Garrido N, Comi G, Morandi L, Santoro L, Toscano A, Fabrizi GM, Somer H, Croxen R, Beeson D, Poulton J, Suomalainen A, Jacobs HT, Zeviani M, Larsson C (2001) Human mitochondrial DNA deletions associated with mutations in the gene encoding Twinkle, a phage T7 gene 4-like protein localized in mitochondria. Nat Genet 28:223–231PubMedCrossRefGoogle Scholar