TY - JOUR TI - Crenactin forms actin-like double helical filaments regulated by arcadin-2 AU - Izoré, Thierry AU - Kureisaite-Ciziene, Danguole AU - McLaughlin, Stephen H AU - Löwe, Jan A2 - Kühlbrandt, Werner VL - 5 PY - 2016 DA - 2016/11/17 SP - e21600 C1 - eLife 2016;5:e21600 DO - 10.7554/eLife.21600 UR - https://doi.org/10.7554/eLife.21600 AB - The similarity of eukaryotic actin to crenactin, a filament-forming protein from the crenarchaeon Pyrobaculum calidifontis supports the theory of a common origin of Crenarchaea and Eukaryotes. Monomeric structures of crenactin and actin are similar, although their filament architectures were suggested to be different. Here we report that crenactin forms bona fide double helical filaments that show exceptional similarity to eukaryotic F-actin. With cryo-electron microscopy and helical reconstruction we solved the structure of the crenactin filament to 3.8 Å resolution. When forming double filaments, the 'hydrophobic plug' loop in crenactin rearranges. Arcadin-2, also encoded by the arcade gene cluster, binds tightly with its C-terminus to the hydrophobic groove of crenactin. Binding is reminiscent of eukaryotic actin modulators such as cofilin and thymosin β4 and arcadin-2 is a depolymeriser of crenactin filaments. Our work further supports the theory of shared ancestry of Eukaryotes and Crenarchaea. KW - Pyrobaculum calidifontis KW - F-actin KW - bacterial cytoskeleton KW - Crenarchaea KW - MreB KW - arcade cluster JF - eLife SN - 2050-084X PB - eLife Sciences Publications, Ltd ER -