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-Structure paper
タイトル | Actin cytoskeleton and complex cell architecture in an Asgard archaeon. |
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ジャーナル・号・ページ | Nature, Vol. 613, Issue 7943, Page 332-339, Year 2023 |
掲載日 | 2022年12月21日 |
著者 | Thiago Rodrigues-Oliveira / Florian Wollweber / Rafael I Ponce-Toledo / Jingwei Xu / Simon K-M R Rittmann / Andreas Klingl / Martin Pilhofer / Christa Schleper / |
PubMed 要旨 | 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 ...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. A role of ESPs in the formation of an elaborate cytoskeleton and complex cellular structures has been postulated, 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 × 10 cells per ml and has a significantly larger genome compared with the single previously cultivated Asgard strain. 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. |
リンク | Nature / PubMed:36544020 / PubMed Central |
手法 | EM (サブトモグラム平均) / EM (トモグラフィー) |
解像度 | 11.7 - 24.5 Å |
構造データ | EMDB-15987: In situ sub-tomogram average of the Ca. L. ossiferum ribosome EMDB-15988: In situ sub-tomogram average of Ca. L. ossiferum actin filament EMDB-15989: cryo-tomogram of a Ca. L. ossiferum cell EMDB-15990: cryo-tomogram of Ca. L. ossiferum protrusions EMDB-15991: cryo-tomogram of a Ca.L. ossiferum cell EMDB-15992: cryo-tomogram of a Ca. L. ossiferum cell EMDB-15993: cryo-tomogram of a Ca. L. ossiferum cell |
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