TopoVIL

Robert, Thomas; Massy, Bernard de; Grelon, Mathilde

doi:10.1051/medsci/20173305015

“…In most eukaryotes, prophase of the first meiotic division is characterized by the programmed formation of DNA double-strand breaks (DSBs) catalyzed by the SPO11/TOPOVIBL complex and their repair through recombination with the homologous chromosome (Keeney et al, 2014;de Massy, 2013;Robert et al, 2016). Meiotic recombination plays essential roles in promoting the recognition, pairing, and accurate segregation of homologous chromosomes (Hunter, 2015).…”

Section: Introductionmentioning

confidence: 99%

PRDM9 Methyltransferase Activity Is Essential for Meiotic DNA Double-Strand Break Formation at Its Binding Sites

Diagouraga

¹

,

Clément

²

,

Duret

³

et al. 2018

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The programmed formation of hundreds of DNA double-strand breaks (DSBs) is essential for proper meiosis and fertility. In mice and humans, the location of these breaks is determined by the meiosis-specific protein PRDM9, through the DNA-binding specificity of its zinc-finger domain. PRDM9 also has methyltransferase activity. Here, we show that this activity is required for H3K4me3 and H3K36me3 deposition and for DSB formation at PRDM9-binding sites. By analyzing mice that express two PRDM9 variants with distinct DNA-binding specificities, we show that each variant generates its own set of H3K4me3 marks independently from the other variant. Altogether, we reveal several basic principles of PRDM9-dependent DSB site determination, in which an excess of sites are designated through PRDM9 binding and subsequent histone methylation, from which a subset is selected for DSB formation.

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“…A likely answer is that they relied on Topo IIB, since this enzyme is ubiquitous in Archaea, but also present in many eukaryotes. A Topo IIB-like protein with a very divergent V-B subunit is present in all eukaryotes and is part of the complex responsible for initiation of meiotic recombination (Vrielynck et al 2016;Robert et al 2017) whereas several eukaryotic lineages, e.g., Viridiplantae, contain a bona fide archaeal-like Topo IIB (Forterre et al 2007;Malik et al 2007;Forterre and Gadelle 2009).…”

Section: Pam Cluster Included Viruses Corresponding To the Recently P...mentioning

confidence: 99%

Viral origin of eukaryotic type IIA DNA topoisomerases

Guglielmini

¹

,

Gaïa

²

,

Cunha³

et al. 2022

Preprint

1

0

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Type II DNA topoisomerases of the family A (Topo IIA) are present in all bacteria (DNA gyrase) and eukaryotes. In eukaryotes, they play a major role in transcription, DNA replication, chromosome segregation and modulation of chromosome architecture. The origin of eukaryotic Topo IIA remains mysterious since they are very divergent from their bacterial homologues and have no orthologues in Archaea. Interestingly, eukaryotic Topo IIA have close homologues in viruses of the phylum Nucleocytoviricota, an expansive assemblage of large and giant viruses formerly known as the nucleocytoplasmic large DNA viruses (NCLDV). Topo IIA are also encoded by some bacterioviruses of the class Caudoviricetes (tailed bacteriophages). To elucidate the origin of the eukaryotic Topo IIA, we performed in-depth phylogenetic analyses combining viral and cellular Topo IIA homologs. Topo IIA encoded by bacteria and eukaryotes form two monophyletic groups nested within Topo IIA encoded by Caudoviricetes and Nucleocytoviricota, respectively. Importantly, Nucleocytoviricota remained well separated from eukaryotes after removing both bacteria and Caudoviricetes from the dataset, indicating that the separation of Nucleocytoviricota and eukaryotes is probably not due to long branch attraction artefact. The topology of our tree suggests that the eukaryotic Topo IIA was probably acquired from an ancestral member of the Nucleocytoviricota of the class Megaviricetes, before the emergence of the last eukaryotic common ancestor (LECA). This result further highlights a key role of these viruses in eukaryogenesis and suggests that early proto-eukaryotes used a Topo IIB instead of a Topo IIA for solving their DNA topological problems.

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Viral origin of eukaryotic type IIA DNA topoisomerases

Guglielmini

¹

,

Gaïa

²

,

Cunha

³

et al. 2022

View full text Add to dashboard Cite

Type II DNA topoisomerases of the family A (Topo IIA) are present in all bacteria (DNA gyrase) and eukaryotes. In eukaryotes, they play a major role in transcription, DNA replication, chromosome segregation and modulation of chromosome architecture. The origin of eukaryotic Topo IIA remains mysterious since they are very divergent from their bacterial homologues and have no orthologues in Archaea. Interestingly, eukaryotic Topo IIA have close homologues in viruses of the phylum Nucleocytoviricota, an expansive assemblage of large and giant viruses formerly known as the nucleocytoplasmic large DNA viruses (NCLDV). Topo IIA are also encoded by some bacterioviruses of the class Caudoviricetes (tailed bacteriophages). To elucidate the origin of the eukaryotic Topo IIA, we performed in-depth phylogenetic analyses combining viral and cellular Topo IIA homologs. Topo IIA encoded by bacteria and eukaryotes form two monophyletic groups nested within Topo IIA encoded by Caudoviricetes and Nucleocytoviricota, respectively. Importantly, Nucleocytoviricota remained well separated from eukaryotes after removing both bacteria and Caudoviricetes from the dataset, indicating that the separation of Nucleocytoviricota and eukaryotes is probably not due to long branch attraction artefact. The topology of our tree suggests that the eukaryotic Topo IIA was probably acquired from an ancestral member of the Nucleocytoviricota of the class Megaviricetes, before the emergence of the last eukaryotic common ancestor (LECA). This result further highlights a key role of these viruses in eukaryogenesis and suggests that early proto-eukaryotes used a Topo IIB instead of a Topo IIA for solving their DNA topological problems

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TopoVIL

Cited by 3 publications

References 24 publications

PRDM9 Methyltransferase Activity Is Essential for Meiotic DNA Double-Strand Break Formation at Its Binding Sites

PRDM9 Methyltransferase Activity Is Essential for Meiotic DNA Double-Strand Break Formation at Its Binding Sites

Viral origin of eukaryotic type IIA DNA topoisomerases

Viral origin of eukaryotic type IIA DNA topoisomerases

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