An actin-based cytoskeleton in archaea

Thijs J.G. Ettema*, Ann Christin Lindås, Rolf Bernander

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

79 Citations (Scopus)


In eukaryotic and bacterial cells, spatial organization is dependent upon cytoskeletal filaments. Actin is a main eukaryotic cytoskeletal element, involved in key processes such as cell shape determination, mechanical force generation and cytokinesis. We describe an archaeal cytoskeleton which forms helical structures within Pyrobaculum calidifontis cells, as shown by in situ immunostaining. The core components include an archaeal actin homologue, Crenactin, closely related to the eukaryotic counterpart. The crenactin gene belongs to a conserved gene cluster denoted Arcade (actin-related cytoskeleton in Archaea involved in shape determination). The phylogenetic distribution of arcade genes is restricted to the crenarchaeal Thermoproteales lineage, and to Korarchaeota, and correlates with rod-shaped and filamentous cell morphologies. Whereas Arcadin-1, -3 and -4 form helical structures, suggesting cytoskeleton-associated functions, Arcadin-2 was found to be localized between segregated nucleoids in a cell subpopulation, in agreement with possible involvement in cytokinesis. The results support a crenarchaeal origin of the eukaryotic actin cytoskeleton and, as such, have implications for theories concerning the origin of the eukaryotic cell.

Original languageEnglish
Pages (from-to)1052-1061
Number of pages10
JournalMolecular Microbiology
Issue number4
Publication statusPublished - 1 May 2011
Externally publishedYes

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