title: Structural insights into the regulatory particle of the proteasome from Methanocaldococcus jannaschii.
abstract: Eukaryotic proteasome consists of a core particle (CP), which degrades unfolded protein, and a regulatory particle (RP), which is responsible for recognition, ATP-dependent unfolding, and translocation of polyubiquitinated substrate protein. In the archaea Methanocaldococcus jannaschii, the RP is a homohexameric complex of proteasome-activating nucleotidase (PAN). Here, we report the crystal structures of essential elements of the archaeal proteasome: the CP, the ATPase domain of PAN, and a distal subcomplex that is likely the first to encounter substrate. The distal subcomplex contains a coiled-coil segment and an OB-fold domain, both of which appear to be conserved in the eukaryotic proteasome. The OB domains of PAN form a hexameric ring with a 13 A pore, which likely constitutes the outermost constriction of the substrate translocation channel. These studies reveal structural codes and architecture of the complete proteasome, identify potential substrate-binding sites, and uncover unexpected asymmetry in the RP of archaea and eukaryotes.
authors.affiliation: Department of Molecular Biology, Lewis Thomas Laboratory, Princeton University, Princeton, NJ 08544, USA.
authors.forename: Fan
authors.initials: F
authors.lastname: Zhang
authors.forename: Min
authors.initials: M
authors.lastname: Hu
authors.forename: Geng
authors.initials: G
authors.lastname: Tian
authors.forename: Ping
authors.initials: P
authors.lastname: Zhang
authors.forename: Daniel
authors.initials: D
authors.lastname: Finley
authors.forename: Philip D
authors.initials: PD
authors.lastname: Jeffrey
authors.forename: Yigong
authors.initials: Y
authors.lastname: Shi
mesh_terms: D000251:Adenosine Triphosphatases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D000595:Amino Acid Sequence; D019843:Archaeal Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006801:Humans; D017015:Methanococcales / Q000201:enzymology* / Q000235:genetics; D008958:Models, Molecular; D008969:Molecular Sequence Data; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D011487:Protein Conformation; D017510:Protein Folding; D021122:Protein Subunits / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D019843:Archaeal Proteins; D021122:Protein Subunits; D046988:Proteasome Endopeptidase Complex; D000251:Adenosine Triphosphatases; C420334:PAN enzyme