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Redrejo-Rodríguez M, Ordóñez CD, Berjón-Otero M, Moreno-González J, Aparicio-Maldonado C, Forterre P, Salas M, Krupovic M. Primer-Independent DNA Synthesis by a Family B DNA Polymerase from Self-Replicating Mobile Genetic Elements. Cell Rep 2018; 21:1574-1587. [PMID: 29117562 PMCID: PMC5695915 DOI: 10.1016/j.celrep.2017.10.039] [Citation(s) in RCA: 21] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2017] [Revised: 09/19/2017] [Accepted: 10/11/2017] [Indexed: 01/06/2023] Open
Abstract
Family B DNA polymerases (PolBs) play a central role during replication of viral and cellular chromosomes. Here, we report the discovery of a third major group of PolBs, which we denote primer-independent PolB (piPolB), that might be a link between the previously known protein-primed and RNA/DNA-primed PolBs. PiPolBs are encoded by highly diverse mobile genetic elements, pipolins, integrated in the genomes of diverse bacteria and also present as circular plasmids in mitochondria. Biochemical characterization showed that piPolB displays efficient DNA polymerization activity that can use undamaged and damaged templates and is endowed with proofreading and strand displacement capacities. Remarkably, the protein is also capable of template-dependent de novo DNA synthesis, i.e., DNA-priming activity, thereby breaking the long-standing dogma that replicative DNA polymerases require a pre-existing primer for DNA synthesis. We suggest that piPolBs are involved in self-replication of pipolins and may also contribute to bacterial DNA damage tolerance.
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Affiliation(s)
- Modesto Redrejo-Rodríguez
- Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain.
| | - Carlos D Ordóñez
- Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
| | - Mónica Berjón-Otero
- Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
| | - Juan Moreno-González
- Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
| | - Cristian Aparicio-Maldonado
- Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain
| | - Patrick Forterre
- Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Paris, France
| | - Margarita Salas
- Centro de Biología Molecular "Severo Ochoa," Consejo Superior de Investigaciones Científicas and Universidad Autónoma de Madrid, Universidad Autónoma, Cantoblanco, 28049 Madrid, Spain.
| | - Mart Krupovic
- Institut Pasteur, Unité Biologie Moléculaire du Gène chez les Extrêmophiles, Paris, France.
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Vergara M, Capasso T, Gobbi E, Vannacci G. Plasmid distribution in European Diaporthe helianthi isolates. Mycopathologia 2005; 159:591-9. [PMID: 15983747 DOI: 10.1007/s11046-005-1327-0] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2004] [Accepted: 01/27/2005] [Indexed: 10/25/2022]
Abstract
Diaporthe helianthi is the causal agent of sunflower stem canker, a serious pathogen of sunflower in Europe, which has been sporadically recorded in Italy. A collection of 26 Diaporthe helianthi isolates deriving from different geographic origins was analysed in order to determine the presence of extra-chromosomal genetic determinants and their molecular diversity. Extra-chromosomal bands in total genomic DNAs were identified in every French and the Yugoslavian isolate and in only one Italian isolate, while no Romanian and Argentinean isolates resulted to host any plasmids. When tested for their chemicophysical nature, they were recognised as linear plasmids sized about 2.3 Kb. A more detailed analysis was performed on a plasmid purified from a French isolate (plasmid F). Its intracellular localisation resulted as mitochondrial. Plasmid F was also exploited as a probe in Southern hybridisation experiments, in which it recognised only plasmids present in the genomes of French and Yugoslavian isolates (countries were the disease has a heavy incidence) indicating a strong correlation to geographic origin. An RFLP hybridisation analysis performed on genomic DNAs revealed a homogeneous restriction pattern in all French and Yugoslavian isolates, suggesting molecular homology among plasmids present in those isolates.
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Affiliation(s)
- Mariarosaria Vergara
- Dipartimento di Coltivazione e Difesa delle Specie Legnose G. Scaramuzzi Sez. Patologia Vegetale, Via del Borghetto 80, 56124, Pisa, Italy.
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Bertrand H. Role of Mitochondrial DNA in the Senescence and Hypovirulence of Fungi and Potential for Plant Disease Control. ANNUAL REVIEW OF PHYTOPATHOLOGY 2000; 38:397-422. [PMID: 11701848 DOI: 10.1146/annurev.phyto.38.1.397] [Citation(s) in RCA: 45] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/23/2023]
Abstract
The unique coenocytic anatomy of the mycelia of the filamentous fungi and the formation of anastomoses between hyphae from different mycelia enable the intracellular accumulation and infectious transmission of plasmids and mutant mitochondrial DNAs (mtDNAs) that cause senescence. For reasons that are not fully apparent, mitochondria that are rendered dysfunctional by so-called "suppressive" mtDNA mutations proliferate rapidly in growing cells and gradually displace organelles that contain wild-type mtDNA molecules and are functional. The consequence of this process is senescence and death if the suppressive mtDNA contains a lethal mutation. Suppressive mtDNA mutations and mitochondrial plasmids can elicit cytoplasmically transmissible "mitochondrial hypovirulence" syndromes in at least some of the phytopathogenic fungi. In the chestnut-blight fungus Cryphonectria parasitica, the pattern of asexual transmission of mutant mtDNAs and mitochondrial plasmids resembles the pattern of "infectious" transmission displayed by the attenuating virus that is most commonly used for the biological control of this fungus. At least some of the attenuating mitochondrial hypovirulence factors are inherited maternally in crosses, whereas the viruses are not transmitted sexually. The natural control of blight in an isolated stand of chestnut trees has resulted from the invasion of the local population of C. parasitica by a senescence-inducing mutant mtDNA. Moreover, a mitochondrial plasmid, pCRY1, attenuates at least some virulent strains of C. parasitica, suggesting that such factors could be applied to control plant diseases caused by fungi.
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Affiliation(s)
- Helmut Bertrand
- Department of Microbiology, Michigan State University, East Lansing, Michigan 48824; e-mail:
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