The 19S complex of the proteasome regulates nucleotide excision repair in yeast

Previous studies suggest that the amino-terminal ubiquitin-like (ubl) domai n of Rad23 protein can recruit the proteasome for a stimulatory role during nucleotide excision repair in the yeast Saccharomyces cerevisiae. In this report, we show that the 19S regulatory complex of the yeast proteasome can affect nucleotide excision repair independently of Rad23 protein. Strains with mutations in 19S regulatory subunits (but not 20S subunits) of the pro teasome promote partial recovery of nucleotide excision repair in vivo in r ad23 deletion mutants, but not in other nucleotide excision repair-defectiv e strains tested. In addition, a strain that expresses a temperature-degrad able ATPase subunit of the 19S regulatory complex manifests a dramatically increased rate of nucleotide excision repair in vivo. These data indicate t hat the 19S regulatory complex of the 26S proteasome can negatively regulat e the rate of nucleotide excision repair in yeast and suggest that Rad23 pr otein not only recruits the 19S regulatory complex, but also can mediate fu nctional interactions between the 19S regulatory complex and the nucleotide excision repair machinery. The 19S regulatory complex of the yeast:proteas ome functions in nucleotide excision repair independent of proteolysis.