2009-07-30
Bacillus subtilis polynucleotide phosphorylase 3′-to-5′ DNase activity is involved in DNA repair
Publication
Publication
Nucleic Acids Research , Volume 37 - Issue 12 p. 4157- 4169
In the presence of Mn2+, an activity in a preparation of purified Bacillus subtilis RecN degrades single-stranded (ss) DNA with a 3′ → 5′ polarity. This activity is not associated with RecN itself, because RecN purified from cells lacking polynucleotide phosphorylase (PNPase) does not show the exonuclease activity. We show here that, in the presence of Mn2+and low-level inorganic phosphate (Pi), PNPase degrades ssDNA. The limited end-processing of DNA is regulated by ATP and is inactive in the presence of Mg2+or high-level Pi. In contrast, the RNase activity of PNPase requires Mg2+and Pi, suggesting that PNPase degradation of RNA and ssDNA occur by mutually exclusive mechanisms. A null pnpA mutation (Δ pnpA) is not epistatic with Δ recA, but is epistatic with Δ recN and Δ ku, which by themselves are non-epistatic. The addA 5, Δ recO, Δ recQ (Δ recJ), Δ recU and Δ recG mutations (representative of different epistatic groups), in the context of Δ pnpA, demonstrate gain- or loss-of-function by inactivation of repair-by-recombination, depending on acute or chronic exposure to the damaging agent and the nature of the DNA lesion. Our data suggest that PNPase is involved in various nucleic acid metabolic pathways, and its limited ssDNA exonuclease activity plays an important role in RecA-dependent and RecA-independent repair pathways.
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| doi.org/10.1093/nar/gkp314, hdl.handle.net/1765/24690 | |
| Nucleic Acids Research | |
| Organisation | Erasmus MC: University Medical Center Rotterdam |
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Cardenas, P., Carrasco, B., Sanchez, H., Deikus, G., Bechhofer, D., & Alonso, J. (2009). Bacillus subtilis polynucleotide phosphorylase 3′-to-5′ DNase activity is involved in DNA repair. Nucleic Acids Research, 37(12), 4157–4169. doi:10.1093/nar/gkp314 |
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