Structure of Crenactin, an Archaeal Actin Homologue Active at 90Degc.
Lindas, A.C., Chruszcz, M., Bernander, R., Valegard, K.(2014) Acta Crystallogr D Biol Crystallogr 70: 492
- PubMed: 24531483 
- DOI: https://doi.org/10.1107/S1399004714000935
- Primary Citation of Related Structures:  
4BQL - PubMed Abstract: 
The crystal structure of the archaeal actin, crenactin, from the rod-shaped hyperthermophilic (optimal growth at 90°C) crenarchaeon Pyrobaculum calidifontis is reported at 3.35 Å resolution. Despite low amino-acid sequence identity, the three-dimensional structure of the protein monomer is highly similar to those of eukaryotic actin and the bacterial MreB protein. Crenactin-specific features are also evident, as well as elements that are shared between crenactin and eukaryotic actin but are not found in MreB. In the crystal, crenactin monomers form right-handed helices, demonstrating that the protein is capable of forming filament-like structures. Monomer interactions in the helix, as well as interactions between crenactin and ADP in the nucleotide-binding pocket, are resolved at the atomic level and compared with those of actin and MreB. The results provide insights into the structural and functional properties of a heat-stable archaeal actin and contribute to the understanding of the evolution of actin-family proteins in the three domains of life.
Organizational Affiliation: 
Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.