Proposal of the reverse flow model for the origin of the eukaryotic cell based on comparative analyses of Asgard archaeal metabolism

Autor: Nina Dombrowski, Eva F. Caceres, Thijs J. G. Ettema, Jonathan Lombard, Chris Greening, Courtney W. Stairs, Anja Spang, Brett J. Baker, Laura Eme
Přispěvatelé: Royal Netherlands Institute for Sea Research (NIOZ), Utrecht University [Utrecht], Ecologie Systématique et Evolution (ESE), AgroParisTech-Université Paris-Saclay-Centre National de la Recherche Scientifique (CNRS), Université Paris-Sud - Paris 11 (UP11)-AgroParisTech-Centre National de la Recherche Scientifique (CNRS), University of Otago [Dunedin, Nouvelle-Zélande], University of Texas at Austin [Austin], Uppsala University
Jazyk: angličtina
Rok vydání: 2019
Předmět:
Zdroj: Nature Microbiology, 4, 1138-1148
Nature Microbiology
Nature Microbiology, Nature Publishing Group, 2019, 4 (7), pp.1138-1148. ⟨10.1038/s41564-019-0406-9⟩
Nature Microbiology 4 (2019)
ISSN: 2058-5276
DOI: 10.1038/s41564-019-0406-9⟩
Popis: The origin of eukaryotes represents an unresolved puzzle in evolutionary biology. Current research suggests that eukaryotes evolved from a merger between a host of archaeal descent and an alphaproteobacterial endosymbiont. The discovery of the Asgard archaea, a proposed archaeal superphylum that includes Lokiarchaeota, Thorarchaeota, Odinarchaeota and Heimdallarchaeota suggested to comprise the closest archaeal relatives of eukaryotes, has helped to elucidate the identity of the putative archaeal host. Whereas Lokiarchaeota are assumed to employ a hydrogen-dependent metabolism, little is known about the metabolic potential of other members of the Asgard superphylum. We infer the central metabolic pathways of Asgard archaea using comparative genomics and phylogenetics to be able to refine current models for the origin of eukaryotes. Our analyses indicate that Thorarchaeota and Lokiarchaeota encode proteins necessary for carbon fixation via the Wood–Ljungdahl pathway and for obtaining reducing equivalents from organic substrates. By contrast, Heimdallarchaeum LC2 and LC3 genomes encode enzymes potentially enabling the oxidation of organic substrates using nitrate or oxygen as electron acceptors. The gene repertoire of Heimdallarchaeum AB125 and Odinarchaeum indicates that these organisms can ferment organic substrates and conserve energy by coupling ferredoxin reoxidation to respiratory proton reduction. Altogether, our genome analyses suggest that Asgard representatives are primarily organoheterotrophs with variable capacity for hydrogen consumption and production. On this basis, we propose the ‘reverse flow model’, an updated symbiogenetic model for the origin of eukaryotes that involves electron or hydrogen flow from an organoheterotrophic archaeal host to a bacterial symbiont. Comparative genome and phylogenetic analyses of Asgard archaea reveal their metabolic potential and lead to the proposal of a revised model for eukaryogenesis, termed the reverse flow model.
Databáze: OpenAIRE
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