Our archaeal origins: Inference and reconstruction of the Asgard archaeal ancestors of eukaryotes

The origin of eukaryotes is one of the most mysterious major transitions in evolution. This process was essential to the gain in cellular complexity that allowed the diversification of multicellular organisms, such as animals, plants and fungi. This event was caused by the symbiosis of two or more bacteria and archaea, which fused into a cell that became the ancestor of all living eukaryotes. Recent advances in sequencing technologies and computational methods have allowed getting closer into identifying the partners involved and their characteristics. In order to investigate the identity of the closest archaeal relatives of eukaryotes, we analysed a large metagenomic dataset (including novel and published data) using genomic and phylogenomic methods, and were able to pinpoint with high precision the position of eukaryotes within the archaeal group called Asgard archaea. Based on these results, we reconstructed the genome of the last archaeal eukaryotic ancestor. These datasets and results also generated the necessary framework to characterise Asgard archaeal membrane remodeling through the study of homologs of the ESCRT-Ubiquitin system, as well as the identification of Asgard archaeal homologs of other eukaryotic proteins. Moreover, observations stemming from this dataset produced the first identification of viruses in Asgard archaea, thus starting to delineate the mobilome dynamics at the archaeal-eukaryotic interface. Altogether, this work provides key insights into the prokaryote-to-eukaryote transition and brings us closer than ever to understanding the emergence of cellular complexity in eukaryotic cells. 

There will be a 35-min presentation followed by a 15-min in-depth discussion.

Speaker overview

Dr. Daniel Tamarit is an evolutionary microbiologist who obtained his PhD from the laboratory of Siv Andersson at Uppsala University in Sweden. His PhD focused on the genomics of symbiotic bacteria that live inside ants and honeybees, and he was awarded the Linnaeus prize for the best thesis in biology in 2017 by the Swedish Royal Society of Sciences in Uppsala. After completing his PhD, Daniel moved to Wageningen University funded by a postdoc grant from the Swedish Research Council, where he joined the laboratory of Thijs Ettema to study deep evolutionary events such as the origin of eukaryotes and the evolution of recently discovered prokaryotic groups. In 2023, Daniel became assistant professor at the department of Theoretical Biology and Bioinformatics at Utrecht University. Here, he is forming the Archaeal and Bacterial Evolution team, which focuses on fundamental questions in genome evolution.

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