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. 2022 Feb 3;39(2):msac022.
doi: 10.1093/molbev/msac022.

Giant Viruses Encode Actin-Related Proteins

Violette Da Cunha  1 , Morgan Gaia  2 , Hiroyuki Ogata  3 , Olivier Jaillon  2   4 , Tom O Delmont  2 , Patrick Forterre  1   5
Affiliations

Giant Viruses Encode Actin-Related Proteins

Violette Da Cunha et al. Mol Biol Evol. .

Abstract

The emergence of the eukaryotic cytoskeleton is a critical yet puzzling step of eukaryogenesis. Actin and actin-related proteins (ARPs) are ubiquitous components of this cytoskeleton. The gene repertoire of the Last Eukaryotic Common Ancestor (LECA) would have therefore harbored both actin and various ARPs. Here, we report the presence and expression of actin-related genes in viral genomes (viractins) of some Imitervirales, a viral order encompassing the giant Mimiviridae. Phylogenetic analyses suggest an early recruitment of an actin-related gene by viruses from ancient protoeukaryotic hosts before the emergence of modern eukaryotes, possibly followed by a back transfer that gave rise to eukaryotic actins. This supports a coevolutionary scenario between pre-LECA lineages and their viruses, which could have contributed to the emergence of the modern eukaryotic cytoskeleton.

Keywords: NucleoCytoplasmic Large DNA virus; actin and actin-related proteins; viral eukaryogenesis.

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Figures

Fig. 1.
Fig. 1.
Viractins within the different ARPs and actin clades of our initial protein sequence data set. Maximum-likelihood phylogenetic tree of our initial protein data set (GD), which included eukaryotic actin (green) and ARP (yucky green), asgardactin (light blue-green), newly identified bathyactin (orange), viractin (purple), and crenactin (black) sequences. These latter were used as outgroup. The predicted structures obtained for representatives of different clades (supplementary table S2, Supplementary Material online) are shown, as well as the structures for actin and ARP-8. The positions of the conventional actin and of the closely related viractin 01, 02, and 03 sequences are indicated in red.
Fig. 2.
Fig. 2.
Evolutionary relationships between conventional actin and viractins, and putative scenarios. The left panel displays a phylogenetic tree of eukaryotic actin (green) and viractin 01–03 (purple) using eukaryotic ARP-01 (yucky green) sequences as the outgroup (377 positions). Values at nodes represent their support computed by transfer bootstrap estimation (detailed tree in supplementary fig. S4, Supplementary Material online; aLRT and UFBoot support for the same tree are provided in supplementary fig. S8, Supplementary Material online). The scale bar indicates the average number of substitutions per site. The right panel displays two hypothetical scenarios of evolution for the actin based on new insights provided by the viractins.
See this image and copyright information in PMC

References

    1. Akıl C, Kitaoku Y, Tran LT, Liebl D, Choe H, Muengsaen D, Suginta W, Schulte A, Robinson RC.. 2021. Mythical origins of the actin cytoskeleton. Curr Opin Cell Biol. 68:55–63. - PubMed
    1. Archer SK, Claudianos C, Campbell HD.. 2005. Evolution of the gelsolin family of actin-binding proteins as novel transcriptional coactivators. Bioessays 27(4):388–396. - PubMed
    1. Bajrai LH, Mougari S, Andreani J, Baptiste E, Delerce J, Raoult D, Azhar EI, La Scola B, Levasseur A.. 2019. Isolation of Yasminevirus, the first member of Klosneuvirinae isolated in coculture with Vermamoeba vermiformis, demonstrates an extended arsenal of translational apparatus components. J Virol. 94(1):e01534-19. - PMC - PubMed
    1. Bajusz C, Borkúti P, Kristó I, Kovács Z, Abonyi C, Vilmos P.. 2018. Nuclear actin: ancient clue to evolution in eukaryotes? Histochem Cell Biol. 150(3):235–244. - PubMed
    1. Bell PJL. 2020. Evidence supporting a viral origin of the eukaryotic nucleus. Virus Res. 289:198168. - PubMed

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