Journal
VIRUS EVOLUTION
Volume 8, Issue 2, Pages -Publisher
OXFORD UNIV PRESS
DOI: 10.1093/ve/veac097
Keywords
DNA topoisomerases; virus evolution; NCLDV; Nucleocytoviricoya; Duplodnavira; eukaryogenesis
Categories
Funding
- Emergence(s) grant from Ville de Paris
Ask authors/readers for more resources
Type II DNA topoisomerases of the family A (Topo IIAs) are present in all Bacteria and eukaryotes. The origin of eukaryotic Topo IIA remains mysterious, but they have close homologs in large viruses and may have been acquired from them. This highlights the important role of viruses in eukaryogenesis and suggests early proto-eukaryotes used a different type of topoisomerase to solve DNA topological problems.
Type II DNA topoisomerases of the family A (Topo IIAs) 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 homologs and have no orthologs in Archaea. Interestingly, eukaryotic Topo IIAs have close homologs in viruses of the phylum Nucleocytoviricota, an expansive assemblage of large and giant viruses formerly known as the nucleocytoplasmic large DNA viruses. Topo IIAs 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 on a dataset combining viral and cellular Topo IIA homologs. Topo IIAs 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 data set, indicating that the separation of Nucleocytoviricota and eukaryotes is probably not due to long-branch attraction artifact. The topologies of our trees suggest 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.
Authors
I am an author on this paper
Click your name to claim this paper and add it to your profile.
Reviews
Recommended
No Data Available