| Autor: |
Vance JR; Department of Pathology, University of Michigan Medical School, Ann Arbor, Michigan 48109-0602, USA., Wilson TE |
| Jazyk: |
angličtina |
| Zdroj: |
The Journal of biological chemistry [J Biol Chem] 2001 May 04; Vol. 276 (18), pp. 15073-81. Date of Electronic Publication: 2001 Jan 30. |
| DOI: |
10.1074/jbc.M011075200 |
| Abstrakt: |
Polynucleotide kinase is a bifunctional enzyme containing both DNA 3'-phosphatase and 5'-kinase activities seemingly suited to the coupled repair of single-strand nicks in which the phosphate has remained with the 3'-base. We show that the yeast Saccharomyces cerevisiae is able to repair transformed dephosphorylated linear plasmids by non-homologous end joining with considerable efficiency independently of the end-processing polymerase Pol4p. Homology searches and biochemical assays did not reveal a 5'-kinase that would account for this repair, however. Instead, open reading frame YMR156C (here named TPP1) is shown to encode only a polynucleotide kinase-type 3'-phosphatase. Tpp1p bears extensive similarity to the ancient L-2-halo-acid dehalogenase and DDDD phosphohydrolase superfamilies, but is specific for double-stranded DNA. It is present at high levels in cell extracts in a functional form and so does not represent a pseudogene. Moreover, the phosphatase-only nature of this gene is shared by Saccharomyces mikatae YMR156C and Arabidopsis thaliana K15M2.3. Repair of 3'-phosphate and 5'-hydroxyl lesions is thus uncoupled in budding yeast as compared with metazoans. Repair of transformed dephosphorylated plasmids, and 5'-hydroxyl blocking lesions more generally, likely proceeds by a cycle of base removal and resynthesis. |
| Databáze: |
MEDLINE |
| Externí odkaz: |
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