title: Crystal structures of a group II chaperonin reveal the open and closed states associated with the protein folding cycle.
abstract: Chaperonins are large protein complexes consisting of two stacked multisubunit rings, which open and close in an ATP-dependent manner to create a protected environment for protein folding. Here, we describe the first crystal structure of a group II chaperonin in an open conformation. We have obtained structures of the archaeal chaperonin from Methanococcus maripaludis in both a peptide acceptor (open) state and a protein folding (closed) state. In contrast with group I chaperonins, in which the equatorial domains share a similar conformation between the open and closed states and the largest motions occurs at the intermediate and apical domains, the three domains of the archaeal chaperonin subunit reorient as a single rigid body. The large rotation observed from the open state to the closed state results in a 65% decrease of the folding chamber volume and creates a highly hydrophilic surface inside the cage. These results suggest a completely distinct closing mechanism in the group II chaperonins as compared with the group I chaperonins.
authors.affiliation: Physical Biosciences Division, Lawrence Berkeley National Laboratory, Berkeley, California 94720, USA.
authors.forename: Jose H
authors.initials: JH
authors.lastname: Pereira
authors.forename: Corie Y
authors.initials: CY
authors.lastname: Ralston
authors.forename: Nicholai R
authors.initials: NR
authors.lastname: Douglas
authors.forename: Daniel
authors.initials: D
authors.lastname: Meyer
authors.forename: Kelly M
authors.initials: KM
authors.lastname: Knee
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Goulet
authors.forename: Jonathan A
authors.initials: JA
authors.lastname: King
authors.forename: Judith
authors.initials: J
authors.lastname: Frydman
authors.forename: Paul D
authors.initials: PD
authors.lastname: Adams
mesh_terms: D000255:Adenosine Triphosphate / Q000378:metabolism; D018360:Crystallography, X-Ray; D056385:Group II Chaperonins / Q000737:chemistry* / Q000378:metabolism; D006868:Hydrolysis; D017017:Methanococcus; D008958:Models, Molecular; D017510:Protein Folding; D017434:Protein Structure, Tertiary
chemical_list: D000255:Adenosine Triphosphate; D056385:Group II Chaperonins