title: Structure of crenactin, an archaeal actin homologue active at 90°C.
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.
authors: Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
authors: Ann Christin
authors: AC
authors: Lindås
authors: Department of Chemistry and Biochemistry, University of South Carolina, Columbia, South Carolina, USA.
authors: Maksymilian
authors: M
authors: Chruszcz
authors: Department of Molecular Biosciences, The Wenner-Gren Institute, Stockholm University, Stockholm, Sweden.
authors: Rolf
authors: R
authors: Bernander
authors: Department of Cell and Molecular Biology, Uppsala University, Uppsala, Sweden.
authors: Karin
authors: K
authors: Valegård
mesh_terms: D000199:Actins / Q000737:chemistry* / Q000235:genetics; D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics; D018360:Crystallography, X-Ray; D003598:Cytoskeletal Proteins / Q000737:chemistry* / Q000235:genetics; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D019143:Evolution, Molecular; D006358:Hot Temperature; D008958:Models, Molecular; D008969:Molecular Sequence Data; D055550:Protein Stability; D017433:Protein Structure, Secondary; D017434:Protein Structure, Tertiary; D041543:Pyrobaculum / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000235:genetics; D016415:Sequence Alignment; D017386:Sequence Homology, Amino Acid; D020124:Thermotoga maritima / Q000737:chemistry / Q000378:metabolism
chemical_list: D000199:Actins; D019843:Archaeal Proteins; D001426:Bacterial Proteins; D003598:Cytoskeletal Proteins; C435905:MreB1 protein, Thermotoga maritima; D011994:Recombinant Proteins; D029701:Saccharomyces cerevisiae Proteins
keywords: Pyrobaculum calidifontis; actin family; crenactin