Actin cytoskeleton and complex cell architecture in an Asgard archaeon

Autor(en)
Thiago Rodrigues de Oliveira, Florian Wollweber, Rafael I. Ponce-Toledo, Jingwei Xu, Simon K.M.R. Rittmann, Andreas Klingl, Martin Pilhofer, Christa Schleper
Abstrakt

Asgard archaea are considered to be the closest known relatives of eukaryotes. Their genomes contain hundreds of eukaryotic signature proteins (ESPs), which inspired hypotheses on the evolution of the eukaryotic cell1–3. A role of ESPs in the formation of an elaborate cytoskeleton and complex cellular structures has been postulated4–6, but never visualized. Here we describe a highly enriched culture of ‘Candidatus Lokiarchaeum ossiferum’, a member of the Asgard phylum, which thrives anaerobically at 20 °C on organic carbon sources. It divides every 7–14 days, reaches cell densities of up to 5 × 107 cells per ml and has a significantly larger genome compared with the single previously cultivated Asgard strain7. ESPs represent 5% of its protein-coding genes, including four actin homologues. We imaged the enrichment culture using cryo-electron tomography, identifying ‘Ca. L. ossiferum’ cells on the basis of characteristic expansion segments of their ribosomes. Cells exhibited coccoid cell bodies and a network of branched protrusions with frequent constrictions. The cell envelope consists of a single membrane and complex surface structures. A long-range cytoskeleton extends throughout the cell bodies, protrusions and constrictions. The twisted double-stranded architecture of the filaments is consistent with F-actin. Immunostaining indicates that the filaments comprise Lokiactin—one of the most highly conserved ESPs in Asgard archaea. We propose that a complex actin-based cytoskeleton predated the emergence of the first eukaryotes and was a crucial feature in the evolution of the Asgard phylum by scaffolding elaborate cellular structures.

Organisation(en)
Department für Funktionelle und Evolutionäre Ökologie
Externe Organisation(en)
Eidgenössische Technische Hochschule Zürich, Ludwig-Maximilians-Universität München
Journal
Nature
Band
613
Seiten
332-339
Anzahl der Seiten
8
ISSN
0028-0836
DOI
https://doi.org/10.1038/s41586-022-05550-y
Publikationsdatum
01-2023
Peer-reviewed
Ja
ÖFOS 2012
106022 Mikrobiologie
ASJC Scopus Sachgebiete
General
Link zum Portal
https://ucris.univie.ac.at/portal/de/publications/actin-cytoskeleton-and-complex-cell-architecture-in-an-asgard-archaeon(dde52240-fb95-4a59-873f-e926a37a428d).html