title: Crystal structure of a chaperone complex that contributes to the assembly of yeast 20S proteasomes.
abstract: Eukaryotic 20S proteasomes are composed of two alpha-rings and two beta-rings, which form an alphabetabetaalpha stacked structure. Here we describe a proteasome-specific chaperone complex, designated Dmp1-Dmp2, in budding yeast. Dmp1-Dmp2 directly bound to the alpha5 subunit to facilitate alpha-ring formation. In Deltadmp1 cells, alpha-rings lacking alpha4 and decreased formation of 20S proteasomes were observed. Dmp1-Dmp2 interacted with proteasome precursors early during proteasome assembly and dissociated from the precursors before the formation of half-proteasomes. Notably, the crystallographic structures of Dmp1 and Dmp2 closely resemble that of PAC3-a mammalian proteasome-assembling chaperone; nonetheless, neither Dmp1 nor Dmp2 showed obvious sequence similarity to PAC3. The structure of the Dmp1-Dmp2-alpha5 complex reveals how this chaperone functions in proteasome assembly and why it dissociates from proteasome precursors before the beta-rings are assembled.
authors.affiliation: Laboratory of Frontier Science, Core Technology and Research Center, Tokyo Metropolitan Institute of Medical Science, Bunkyo-ku, Tokyo 113-8613, Japan.
authors.forename: Hideki
authors.initials: H
authors.lastname: Yashiroda
authors.forename: Tsunehiro
authors.initials: T
authors.lastname: Mizushima
authors.forename: Kenta
authors.initials: K
authors.lastname: Okamoto
authors.forename: Tomie
authors.initials: T
authors.lastname: Kameyama
authors.forename: Hidemi
authors.initials: H
authors.lastname: Hayashi
authors.forename: Toshihiko
authors.initials: T
authors.lastname: Kishimoto
authors.forename: Shin-ichiro
authors.initials: S
authors.lastname: Niwa
authors.forename: Masanori
authors.initials: M
authors.lastname: Kasahara
authors.forename: Eiji
authors.initials: E
authors.lastname: Kurimoto
authors.forename: Eri
authors.initials: E
authors.lastname: Sakata
authors.forename: Kenji
authors.initials: K
authors.lastname: Takagi
authors.forename: Atsuo
authors.initials: A
authors.lastname: Suzuki
authors.forename: Yuko
authors.initials: Y
authors.lastname: Hirano
authors.forename: Shigeo
authors.initials: S
authors.lastname: Murata
authors.forename: Koichi
authors.initials: K
authors.lastname: Kato
authors.forename: Takashi
authors.initials: T
authors.lastname: Yamane
authors.forename: Keiji
authors.initials: K
authors.lastname: Tanaka
mesh_terms: D018360:Crystallography, X-Ray; D004792:Enzyme Precursors / Q000378:metabolism; D018832:Molecular Chaperones / Q000737:chemistry* / Q000378:metabolism; D009097:Multienzyme Complexes / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D050505:Mutant Proteins / Q000737:chemistry / Q000302:isolation & purification / Q000378:metabolism; D009154:Mutation / Q000235:genetics; D046988:Proteasome Endopeptidase Complex / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000201:enzymology*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism; D040681:Structural Homology, Protein
chemical_list: D004792:Enzyme Precursors; C527523:IRC25 protein, S cerevisiae; D018832:Molecular Chaperones; D009097:Multienzyme Complexes; D050505:Mutant Proteins; C527522:POC4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D046988:Proteasome Endopeptidase Complex