Meet the relatives of our cellular ancestor

Schleper, Christa; Sousa, Filipa L.

doi:10.1038/d41586-020-00039-y

Cited by 8 publications

(5 citation statements)

References 16 publications

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“…As ‘ Ca. P. syntrophicum’ cells show long branched protrusions, the authors proposed a hypothesis for eukaryogenesis, in which a primordial Asgard archaeon closely interacts with the predecessor of the bacterial endosymbiont and eventually endogenizes it 7 , 27 . These observations were consistent with the stepwise mechanism of eukaryogenesis that was first proposed as the ‘inside out’ model 28 .…”

Section: Mainmentioning

confidence: 99%

Actin cytoskeleton and complex cell architecture in an Asgard archaeon

Rodrigues-Oliveira

Wollweber

Ponce‐Toledo

et al. 2022

Nature

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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.

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Section: Mainmentioning

confidence: 99%

Actin cytoskeleton and complex cell architecture in an Asgard archaeon

Rodrigues-Oliveira

Wollweber

Ponce‐Toledo

et al. 2022

Nature

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“…Some of these archaea have been recently cultured and found to form extensive protrusions involved in heterotrophic feeding, such as amino-acid fermentations [19], but their internal morphology is archetypally prokaryotic in complexity and bears little resemblance to eukaryotes. Various bacteria and archaea are known that form processes including nanowires or cables for electron transfer, so Asgards are by no means unique in their morphological complexity [20]. Nor is their metabolism suggestive of great complexity: a metabolic reconstruction of the last Asgard common ancestor suggests that it may have been limited to hydrogen-dependent anaerobic metabolism using the acetyl CoA pathway [21] -not far up any ramp towards eukaryotic complexity.…”

Section: Magazinementioning

confidence: 99%

How energy flow shapes cell evolution

Lane

2020

Current Biology

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“…A key discovery was the identification of the Lokiarchaeota in deep-sea sediments in the Arctic that had episodic hydrothermal input, possibly from the nearby basalt-hosted hydrothermal vents at Loki's Castle 190 . Lokiarchaeota share many characteristics previously thought to be found only in Eukaryotes, thus promising a better understanding of the evolution of the Eukaryotes 14,190,191 and supporting evidence for placing the Eukaryotes as emerging from the archaeal branch of the tree of life 192,193 .…”

Section: Serpentinization Frontmentioning

confidence: 60%

Diversity of magmatism, hydrothermal processes and microbial interactions at mid-ocean ridges

Früh-Green

Kelley

Lilley

et al. 2022

Nat Rev Earth Environ

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Hydrothermal circulation and alteration at mid-ocean ridges and ridge flanks have a key role in regulating seawater chemistry and global chemical fluxes, and support diverse ecosystems in the absence of light. In this Review, we outline tectonic, magmatic and hydrothermal processes that govern crustal architecture, alteration and biogeochemical cycles along mid-ocean ridges with different spreading rates. In general, hydrothermal systems vary from those that are magmatic-dominated with low-pH fluids >300 °C to serpentinizing systems with alkaline fluids <120 °C. Typically, slow-spreading ridges (rates <40 mm yr −1 ) have greater variability in magmatism, lithology and vent chemistry, which are influenced by detachment faults that expose lower-crustal and serpentinized mantle rocks. Hydrothermal alteration is an important sink for magnesium, sodium, sulfate and bicarbonate, and a net source of volatiles, iron and other nutrients to the deep ocean and vent ecosystems. Magmatic hydrothermal systems sustain a vast, hot and diverse microbial biosphere that represents a deep organic carbon source to ocean carbon budgets. In contrast, high-pH serpentinizing hydrothermal systems harbour a more limited microbial community consisting primarily of methanemetabolizing archaea. Continued advances in monitoring and analytical capabilities coupled with developments in metagenomic technologies will guide future investigations and discoveries in hydrothermal systems. Sections• Basalt-hosted systems support a vast, hot and diverse microbial biosphere, in contrast to serpentinizing systems, which sustain more limited microbial communities primarily dominated by methane-metabolizing archaea. Advanced technologies allow better characterization of the genetic makeup and metabolism of microbes and the role of viruses in shaping diversity.Springer Nature or its licensor (e.g. a society or other partner) holds exclusive rights to this article under a publishing agreement with the author(s) or other rightsholder(s); author selfarchiving of the accepted manuscript version of this article is solely governed by the terms of such publishing agreement and applicable law.

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Meet the relatives of our cellular ancestor

Cited by 8 publications

References 16 publications

Actin cytoskeleton and complex cell architecture in an Asgard archaeon

Actin cytoskeleton and complex cell architecture in an Asgard archaeon

How energy flow shapes cell evolution

Diversity of magmatism, hydrothermal processes and microbial interactions at mid-ocean ridges

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