20S proteasome assembly is orchestrated by two distinct pairs of chaperones in yeast and in mammals.
The 20S proteasome is the catalytic core of the 26S proteasome, a central enzyme in the ubiquitin-proteasome system. Its assembly proceeds in a multistep and orderly fashion. Ump1 is the only well-described chaperone dedicated to the assembly of the 20S proteasome in yeast. Here, we report a phenotype related to the DNA damage response that allowed us to isolate four other chaperones of yeast 20S proteasomes, which we named Poc1-Poc4. Poc1/2 and Poc3/4 form two pairs working at different stages in early 20S proteasome assembly. We identify PAC1, PAC2, the recently described PAC3, and an uncharacterized protein that we named PAC4 as functional mammalian homologs of yeast Poc factors. Hence, in yeast as in mammals, proteasome assembly is orchestrated by two pairs of chaperones acting upstream of the half-proteasome maturase Ump1. Our findings provide evidence for a remarkable conservation of a pairwise chaperone-assisted proteasome assembly throughout evolution.
Le Tallec
Benoît
B
CEA, iBiTecS, SBIGeM, Laboratoire du Métabolisme de l'ADN et Réponses aux Génotoxiques, Gif-sur-Yvette, F-91191, France.
Barrault
Marie-Bénédicte
MB
Courbeyrette
Régis
R
Guérois
Raphaël
R
Marsolier-Kergoat
Marie-Claude
MC
Peyroche
Anne
A
D000818:Animals; D002460:Cell Line; D004249:DNA Damage; D019281:Dimerization; D004843:Epistasis, Genetic; D005800:Genes, Fungal; D006801:Humans; D008322:Mammals / Q000378:metabolism*; D018832:Molecular Chaperones / Q000378:metabolism*; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D011485:Protein Binding; D011498:Protein Precursors / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000166:cytology / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
D018832:Molecular Chaperones; D011498:Protein Precursors; D029701:Saccharomyces cerevisiae Proteins; D046988:Proteasome Endopeptidase Complex