Electron cryo-microscopy of VAT, the archaeal p97/CDC48 homologue from Thermoplasma acidophilum |
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Authors: | Rockel Beate Jakana Joanita Chiu Wah Baumeister Wolfgang |
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Institution: | Max-Planck-Institut für Biochemie, Abteilung Molekulare Strukturbiologie, Am Klopferspitz 18 a, 82152 Martinsried, Germany. Brockel@lbl.gov |
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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. |
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Keywords: | VCP-like ATPase AAA-ATPase 3-D reconstruction electron cryo-microscopy Thermoplasma |
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