Antiviral systems
Immune systems are integral to survival against viral infections. To find a common ancestor of these defense mechanisms, researchers are examining antiviral systems shared by all life forms, from prokaryotes (such as bacteria and archaea) to eukaryotes (animals, plants, and humans). Recently, there has been a growing discussion about a potential bacterial origin of innate immune mechanisms. However, little is known about the role of these defense mechanisms in archaea.
Link between Prokaryotes and Eukaryotes
In this new study, led by dr. Pedro Leão, a new researcher at RIBES together with groups from UT Austin (University of Texas, Austin), the researchers examined defense systems in Asgard archaea, which is the closest relative between prokaryotes and eukaryotes. The study aims to shed light on the origins of proteins involved in the immune system. The researchers combined protein sequence phylogeny, a well-established technique for examining the evolutionary heritage of proteins, with AI-powered protein structure prediction. For this, they focused on two proteins shared by all forms of life: viperins and argonautes. Dr. Pedro Leão: “It was already well established that Asgard archaea contribute to the Eukaryotic cellular complexity we see today. We believe the same applies for their defense mechanisms.”
Common ancestor of antiviral mechanisms
The research demonstrated that Asgard viperins (asVip) are sister proteins to eukaryotic viperins, suggesting that eukaryotic and Asgard viperins evolved from a common ancestor. Moreover, they found that asVip proteins are functional and capable of protecting cells against viral infections.
Regarding argonautes, by positioning Asgard proteins in a sequence and structural context, they uncovered compelling evidence linking eukaryotic and prokaryotic argonautes to ancient Asgard versions of this protein, showing a remarkably high degree of conservation.
