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 cell^1–3. A role of ESPs in the formation of an elaborate cytoskeleton and complex cellular structures has been postulated^4–6, 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://ucrisportal.univie.ac.at/de/publications/dde52240-fb95-4a59-873f-e926a37a428d