A multimeric assembly factor controls the formation of alternative 20S proteasomes.
The proteasome is the central regulatory protease of eukaryotic cells. Heteroheptameric alpha-subunit and beta-subunit rings stack to form the 20S proteasome, which associates with a 19S regulatory particle (RP). Here we show that two yeast proteins, Pba3 and Pba4, form a previously unidentified 20S proteasome-assembly chaperone. Pba3-Pba4 interacts genetically and ... physically with specific proteasomal alpha subunits, and loss of Pba3-Pba4 causes both a reduction and a remodeling of cellular proteasomes. Notably, mutant cells accumulate proteasomes in which a second copy of the alpha4 subunit replaces alpha3. 20S proteasome-assembly defects also are associated with altered RP assembly; this unexpected result suggests that the 20S proteasome can function as an RP-assembly factor in vivo. Our data demonstrate that Pba3-Pba4 orchestrates formation of a specific type of proteasome, the first example of a trans-acting factor that controls assembly of alternative proteasomal complexes.
Mesh Terms:
Computational Biology, Metals, Heavy, Models, Biological, Molecular Chaperones, Multienzyme Complexes, Mutant Proteins, Mutation, Proteasome Endopeptidase Complex, Protein Binding, Protein Structure, Secondary, Protein Subunits, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
Computational Biology, Metals, Heavy, Models, Biological, Molecular Chaperones, Multienzyme Complexes, Mutant Proteins, Mutation, Proteasome Endopeptidase Complex, Protein Binding, Protein Structure, Secondary, Protein Subunits, Saccharomyces cerevisiae, Saccharomyces cerevisiae Proteins
Nat. Struct. Mol. Biol.
Date: Mar. 01, 2008
PubMed ID: 18278055
View in: Pubmed Google Scholar
Download Curated Data For This Publication
96685
Switch View:
- Interactions 13