Polynucleotide phosphorylase exonuclease and polymerase activities on single-stranded DNA ends are modulated by RecN, SsbA and RecA proteins
| Autor: | Federica Briani, Thomas Carzaniga, Esther Garcia-Tirado, Gianni Dehò, Juan C. Alonso, Paula P. Cárdenas, Sandro Zangrossi |
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| Rok vydání: | 2011 |
| Předmět: |
Exonuclease
DNA Single-Stranded Purine nucleoside phosphorylase DNA-Directed DNA Polymerase Bacillus subtilis Genome Integrity Repair and Replication chemistry.chemical_compound Deoxyadenine Nucleotides Bacterial Proteins Escherichia coli Genetics Nucleoid Polynucleotide phosphorylase Polymerase Polyribonucleotide Nucleotidyltransferase Manganese biology DNA Restriction Enzymes biology.organism_classification Rec A Recombinases Exodeoxyribonucleases chemistry Biochemistry biology.protein Homologous recombination DNA |
| Zdroj: | Nucleic Acids Research |
| ISSN: | 1362-4962 0305-1048 |
| DOI: | 10.1093/nar/gkr635 |
| Popis: | Bacillus subtilis pnpA gene product, polynucleotide phosphorylase (PNPase), is involved in double-strand break (DSB) repair via homologous recombination (HR) or non-homologous end-joining (NHEJ). RecN is among the first responders to localize at the DNA DSBs, with PNPase facilitating the formation of a discrete RecN focus per nucleoid. PNPase, which co-purifies with RecA and RecN, was able to degrade single-stranded (ss) DNA with a 3' → 5' polarity in the presence of Mn(2+) and low inorganic phosphate (Pi) concentration, or to extend a 3'-OH end in the presence dNDP · Mn(2+). Both PNPase activities were observed in evolutionarily distant bacteria (B. subtilis and Escherichia coli), suggesting conserved functions. The activity of PNPase was directed toward ssDNA degradation or polymerization by manipulating the Pi/dNDPs concentrations or the availability of RecA or RecN. In its dATP-bound form, RecN stimulates PNPase-mediated polymerization. ssDNA phosphorolysis catalyzed by PNPase is stimulated by RecA, but inhibited by SsbA. Our findings suggest that (i) the PNPase degradative and polymerizing activities might play a critical role in the transition from DSB sensing to end resection via HR and (ii) by blunting a 3'-tailed duplex DNA, in the absence of HR, B. subtilis PNPase might also contribute to repair via NHEJ. |
| Databáze: | OpenAIRE |
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