Deinococcus radiodurans HD-Pnk, a nucleic acid end-healing enzyme, abets resistance to killing by ionizing radiation and mitomycin C Journal Article
| Authors: | Schmier, B. J.; Shuman, S. |
| Article Title: | Deinococcus radiodurans HD-Pnk, a nucleic acid end-healing enzyme, abets resistance to killing by ionizing radiation and mitomycin C |
| Abstract: | 5- and 3 -end healing are key steps in nucleic acid break repair in which 5 -OH and 3 -PO4 or 2 ,3 -cyclic-PO4 ends are converted to 5 -PO4 and 3 -OH termini suitable for sealing by polynucleotide ligases. Here, we characterize Deinococcus radiodurans HD-Pnk as a bifunctional end-healing enzyme composed of N-terminal HD (histidine-aspartate) phosphoesterase and C-terminal P-loop polynucleotide kinase (Pnk) domains. HD-Pnk phosphorylates 5 -OH DNA in the presence of ATP and magnesium. HD-Pnk has 3 -phosphatase and 2 ,3 -cyclic-phosphodiesterase activity in the presence of transition metals, optimally cobalt or copper, and catalyzes copper-dependent hydrolysis of p-nitrophenylphosphate. HD-Pnk is encoded by the LIG-PARG-HD-Pnk three-gene operon, which includes polynucleotide ligase and poly(ADP-ribose) glycohydrolase genes. We show that whereas HD-Pnk is inessential for Deinococcus growth, its absence sensitizes by 80-fold bacteria to killing by 9 kGy of ionizing radiation (IR). HD-Pnk protein is depleted during early stages of post-IR recovery and then replenished at 15 h, after reassembly of the genome from shattered fragments. ΔHD-Pnk mutant cells are competent for genome reassembly, as gauged by pulsed-field gel electrophoresis. Our findings suggest a role for HDPnk in repairing residual single-strand gaps or nicks in the reassembled genome. HD-Pnk-Ala mutations that ablate kinase or phosphoesterase activity sensitize Deinococcus to killing by mitomycin C. © 2018 American Society for Microbiology. |
| Keywords: | dna repair; polynucleotide kinase; hd phosphoesterase |
| Journal Title: | Journal of Bacteriology |
| Volume: | 200 |
| Issue: | 17 |
| ISSN: | 0021-9193 |
| Publisher: | American Society for Microbiology |
| Date Published: | 2018-09-01 |
| Start Page: | e00151-18 |
| Language: | English |
| DOI: | 10.1128/jb.00151-18 |
| PROVIDER: | scopus |
| PMCID: | PMC6088165 |
| PUBMED: | 29891641 |
| DOI/URL: | |
| Notes: | Article -- Export Date: 4 September 2018 -- Source: Scopus |
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