Rad23 Is Required for Transcription-Coupled Repair and Efficient Overall Repair in Saccharomyces cerevisiae

Abstract

The repair of UV-induced photoproducts (cyclobutane pyrimidine dimers) in a well-characterized minichromosome, genomic DNA, and a transcribed genomic gene (RPB2) of a rad23⌬ mutant of Saccharomyces cerevisiae was examined. Isogenic wild-type cells show a strong bias for the repair of the transcribed strands in both the plasmid and genomic genes and efficient overall repair of both DNAs (>80% of the dimers were removed in 6 h). However, the rad23⌬ mutant shows (i) no strand bias for repair in these genes and decreased repair of both strands, (ii) partial repair of genomic DNA (ϳ45% in 6 h), and (iii) very poor repair of the plasmid overall (ϳ15% in 6 h). These features, coupled with the decreased UV survival of rad23⌬ cells, indicate that Rad23 is required for both transcription-coupled repair and efficient overall repair in S. cerevisiae.

The RAD23 Family Provides an Essential Connection between the 26S Proteasome and Ubiquitylated Proteins inArabidopsis

“…Within the UPS, the main receptors are the Ub/UBL binding subunits of the 26S proteasome (RPN1, RPN10, and RPN13) with additional receptors present within the ERAD subpathway that engage substrates before the 26S proteasome (Finley, 2009). UBL/UBA proteins also likely participate in extraproteasomal events, such as vesicular trafficking, DNA repair, and transcriptional regulation by docking ubiquitylated proteins with appropriate components (Mueller and Smerdon, 1996;Ortolan et al, 2004;Gabriely et al, 2008).…”

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

“…Such mutants, however, display a level of UV radiation sensitivity that is intermediate between that of wild-type strains and strains deleted for other RAD genes that are indispensable for NER, such as RAD1, RAD2, RAD3, etc. (Watkins et al 1993;Mueller and Smerdon 1996). In some studies, this intermediate UV radiation sensitivity has been correlated with a partial decrease in NER in vivo (Mueller and Smerdon 1996).…”

“…(Watkins et al 1993;Mueller and Smerdon 1996). In some studies, this intermediate UV radiation sensitivity has been correlated with a partial decrease in NER in vivo (Mueller and Smerdon 1996).Human cells possess two homologs of the yeast RAD23 gene, designated HHR23A and HHR23B (Masutani et al 1994). HHR23B protein binds tightly to human XPC protein and stimulates the rate of NER in vitro (Masutani et al 1994(Masutani et al , 1997Li et al 1997).…”

The Ubiquitin-Proteasome System and DNA Repair

“…Interestingly, proteasome inhibitors such as lactacystin (LC) and N-acetyl-leucyl-leucylnorleucinal (ALLnL) deplete free cellular ubiquitin, thereby negatively affecting protein dynamics of histones, and promote chromatin condensation (Mimnaugh et al, 2000). Yeast protein Rad23 is involved in both NER pathways: GGR and TCR (Mueller & Smerdon, 1996). Rad23 itself is not degraded by the 26S proteasome because it lacks an initiation region for the proteasome to engage and unfold it (Fishbain et al, 2011).…”

“…NER can be divided into repair of overall genomic DNA [global genome repair (GGR)] and repair of actively transcribing genes [transcription-coupled repair (TCR)] (Mueller & Smerdon, 1996). Approximately 30 proteins participate in NER.…”