title: Electron cryo-microscopy of VAT, the archaeal p97/CDC48 homologue from Thermoplasma acidophilum.
abstract: VAT (valosine containing protein-like ATPase from Thermoplasma acidophilum), an archaeal member of the AAA-family (ATPases associated with a variety of cellular activities) that possesses foldase as well as unfoldase-activity, forms homo-hexameric rings like its eukaryotic homologues p97 and CDC48. The VAT-monomer exhibits the tripartite domain architecture typical for type II AAA-ATPases: N-D1-D2, whereby N is the substrate binding N-terminal domain preceding domains D1 and D2, both containing AAA-modules. Recent 3-D reconstructions of VAT and p97 as obtained by electron microscopy suffer from weakly represented N-domains, probably a consequence of their flexible linkage to the hexameric core. Here we used electron cryo-microscopy and 3-D reconstruction of single particles in order to generate a 3-D model of VAT at 2.3 nm resolution. The hexameric core of the VAT-complex (diameter 13.2 nm, height 8.4 nm) encloses a central cavity and the substrate-binding N-domains are clearly arranged in the upper periphery. Comparison with the p97 3-D reconstruction and the recently determined crystal structure of p97-N-D1 suggests a tail-to-tail arrangement of D1 and D2 in VAT.
authors.affiliation: Max-Planck-Institut für Biochemie, Abteilung Molekulare Strukturbiologie, Am Klopferspitz 18 a, 82152 Martinsried, Germany. Brockel@lbl.gov
authors.forename: Beate
authors.initials: B
authors.lastname: Rockel
authors.forename: Joanita
authors.initials: J
authors.lastname: Jakana
authors.forename: Wah
authors.initials: W
authors.lastname: Chiu
authors.forename: Wolfgang
authors.initials: W
authors.lastname: Baumeister
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000648:ultrastructure*; D019843:Archaeal Proteins; D020285:Cryoelectron Microscopy; D008958:Models, Molecular; D020836:Protein Structure, Quaternary; D013822:Thermoplasma / Q000201:enzymology*; D000074405:Valosin Containing Protein
chemical_list: D019843:Archaeal Proteins; D000251:Adenosine Triphosphatases; D000074405:Valosin Containing Protein; C105134:vat protein, Thermoplasma acidophilum