Crystal structure of a chaperone complex that contributes to the assembly of yeast 20S proteasomes.

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.
Mesh Terms:
Crystallography, X-Ray, Enzyme Precursors, Molecular Chaperones, Multienzyme Complexes, Mutant Proteins, Mutation, Proteasome Endopeptidase Complex, Protein Binding, Protein Structure, Secondary, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins, Structural Homology, Protein
Nat. Struct. Mol. Biol.
Date: Mar. 01, 2008
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