Dominant contribution of Asgard archaea to eukaryogenesis
This article has been Reviewed by the following groups
Listed in
- Evaluated articles (Arcadia Science)
Abstract
Origin of eukaryotes is one of the key problems in evolutionary biology. The demonstration that the Last Eukaryotic Common Ancestor (LECA) already contained the mitochondrion, an endosymbiotic organelle derived from an alphaproteobacterium, and the discovery of Asgard archaea, the closest archaeal relatives of eukaryotes inform and constrain evolutionary scenarios of eukaryogenesis. We undertook a comprehensive analysis of the origins of the core eukaryotic genes tracing to the LECA within a rigorous statistical framework centered around evolutionary hypotheses testing using constrained phylogenetic trees. The results reveal dominant contributions of Asgard archaea to the origin of most of the conserved eukaryotic functional systems and pathways. A limited contribution from Alphaproteobacteria was identified, primarily relating to the energy transformation systems and Fe-S cluster biogenesis, whereas ancestry from other bacterial phyla was scattered across the eukaryotic functional landscape, without consistent trends. These findings suggest a model of eukaryogenesis in which key features of eukaryotic cell organization evolved in the Asgard ancestor, followed by the capture of the Alphaproteobacterial endosymbiont, and augmented by numerous but sporadic horizontal acquisition of genes from other bacteria both before and after endosymbiosis.
Article activity feed
-
Asgard
Have you considered doing a similar analysis centered on another archaeal kingdom, for instance, Methanobacteriati (which presumably also share some key associations, like isoprenoid biosynthesis pathways) that aren't a top candidate for the template for eukaryotes? This could be a test of the basic premise but possibly also reveal other connections to archaea.
-
For some biological functions, this diverse bacterial component accounted for the majority of the aELW, and roughly one third of the analyzed KOGs (918 of 3045), and EPOCs (2640 of 6990) were associated neither with known ancestors of endosymbionts, Alphaproteobacteria and Cyanobacteria, nor with Asgard. However, in a sharp contrast to Archaeal associations including information processing, protein glycosylation and trafficking, and others, or oxidative phosphorylation and sulfur metabolism for Alphaproteobacteria, EPOCs associated with diverse other bacteria showed few if any coherent functional trends.
Do you have a hypothesis for why certain bacterial clades were more closely associated than others?
-
These pangenomes include only those genes that are present in at least 67% of the families within each class of bacteria and archaea (see Methods) resulting in an initial database of 13 million sequences
Thanks for a very interesting paper! How did you decide on this cutoff threshold?
-
-