T.J.G.E. and A.-C.L. contributed equally to this work.
An actin-based cytoskeleton in archaea
Article first published online: 6 APR 2011
© 2011 Blackwell Publishing Ltd
Volume 80, Issue 4, pages 1052–1061, May 2011
How to Cite
Ettema, T. J. G., Lindås, A.-C. and Bernander, R. (2011), An actin-based cytoskeleton in archaea. Molecular Microbiology, 80: 1052–1061. doi: 10.1111/j.1365-2958.2011.07635.x
- Issue published online: 9 MAY 2011
- Article first published online: 6 APR 2011
- Accepted manuscript online: 18 MAR 2011 04:26AM EST
- Accepted 8 March, 2011.
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.