The UBA2 domain functions as an intrinsic stabilization signal that protects Rad23 from proteasomal degradation.
The proteasome-interacting protein Rad23 is a long-lived protein. Interaction between Rad23 and the proteasome is required for Rad23's functions in nucleotide excision repair and ubiquitin-dependent degradation. Here, we show that the ubiquitin-associated (UBA)-2 domain of yeast Rad23 is a cis-acting, transferable stabilization signal that protects Rad23 from proteasomal degradation. Disruption of the UBA2 domain converts Rad23 into a short-lived protein that is targeted for degradation through its N-terminal ubiquitin-like domain. UBA2-dependent stabilization is required for Rad23 function because a yeast strain expressing a mutant Rad23 that lacks a functional UBA2 domain shows increased sensitivity to UV light and, in the absence of Rpn10, severe growth defects. The C-terminal UBA domains of Dsk2, Ddi1, Ede1, and the human Rad23 homolog hHR23A have similar protective activities. Thus, the UBA2 domain of Rad23 is an evolutionarily conserved stabilization signal that allows Rad23 to interact with the proteasome without facing destruction.
Heessen
Stijn
S
Microbiology and Tumor Biology Center, Karolinska Institutet, Nobels väg 16, S-171 77 Stockholm, Sweden.
Masucci
Maria G
MG
Dantuma
Nico P
NP
D015153:Blotting, Western; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D002470:Cell Survival / Q000528:radiation effects; D064447:Checkpoint Kinase 2; D004260:DNA Repair; D045643:DNA Repair Enzymes; D004268:DNA-Binding Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D005434:Flow Cytometry; D005656:Fungal Proteins / Q000378:metabolism* / Q000528:radiation effects; D006367:HeLa Cells; D006801:Humans; D011233:Precipitin Tests; D046988:Proteasome Endopeptidase Complex / Q000378:metabolism*; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism* / Q000528:radiation effects; D025801:Ubiquitin / Q000378:metabolism; D014466:Ultraviolet Rays
D018797:Cell Cycle Proteins; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; C086985:RAD23A protein, human; D064447:Checkpoint Kinase 2; D017346:Protein Serine-Threonine Kinases; C067022:RAD53 protein, S cerevisiae; D046988:Proteasome Endopeptidase Complex; D045643:DNA Repair Enzymes