Mms19 protein functions in nucleotide excision repair by sustaining an adequate cellular concentration of the TFIIH component Rad3.
Nucleotide excision repair (NER) is a major cellular defense mechanism against DNA damage. We have investigated the role of Mms19 in NER in the yeast Saccharomyces cerevisiae. NER was deficient in the mms19 deletion mutant cell extracts, which was complemented by the NER/transcription factor TFIIH, but not by purified Mms19 protein. In mms19 mutant cells, protein levels of the core TFIIH component Rad3 (XPD homologue) and Ssl2 (XPB homologue) were significantly reduced by up to 3.5- and 2.2-fold, respectively. The other four essential subunits of the core TFIIH, Tfb1, Tfb2, Ssl1, and Tfb4, and the TFIIK subunits Tfb3, Kin28, and Ccl1 of the holo TFIIH were not much affected by Mms19. Elevating Rad3 protein concentration by overexpressing the protein from a plasmid under the GAL1 promoter control restored proficient NER in mms19 mutant cells, as indicated by complementation for UV sensitivity. Overexpression of Ssl2 had no effect on repair. Overexpression of Rad3, Ssl2, or both proteins, however, could not correct the temperature-sensitive growth defect of mms19 mutant cells. These results show that Mms19 functions in NER by sustaining an adequate cellular concentration of the TFIIH component Rad3 and suggest that Mms19 has distinct and separable functions in NER and cell growth, thus implicating Mms19 protein as a novel multifunctional regulator in cells.
Graduate Center for Toxicology, University of Kentucky, Lexington, KY 40536, USA.
Haiping
H
Kou
Ying
Y
Zhou
R M Charlotte
RM
Gorospe
Zhigang
Z
Wang
D004265:DNA Helicases / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics*; D004260:DNA Repair; D015966:Gene Expression Regulation, Fungal; D029701:Saccharomyces cerevisiae Proteins / Q000032:analysis / Q000096:biosynthesis / Q000235:genetics* / Q000502:physiology*; D051758:Transcription Factor TFIIH; D014157:Transcription Factors
C103317:MET18 protein, S cerevisiae; C489575:SSL2 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D051758:Transcription Factor TFIIH; C061897:Rad3 protein, S cerevisiae; D004265:DNA Helicases