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Spt4 and Spt5 cooperatively suppress transcription coupled DNA repair through binding to RNA polymerase II in the absence of Rad26
Author(s) -
Ding Baojin,
Chen Xuefeng,
Ruggiero Christine,
LeJeune Danielle,
Li Shisheng
Publication year - 2009
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.23.1_supplement.836.6
Subject(s) - rna polymerase ii , transcription (linguistics) , biology , microbiology and biotechnology , transcription factor , dna , gene , genetics , gene expression , promoter , linguistics , philosophy
Rad26, the yeast homolog of human CSB protein, and Rpb9, a nonessential subunit of RNA polymerase II (Pol II), mediate two subpathways of transcription coupled nucleotide excision repair (TC‐NER). However, the deletion of Spt4, a transcription elongation factor, makes both Rad26 and Rpb9 dispensable, suggesting Spt4 works as a suppressor in the modulation of TC‐NER. To examine the molecular mechanism of this modulation, NER activities of different mutants were analyzed by running sequencing gel. The protein‐protein interactions were explored by immunoprecipitation (IP) and Western blot. Here we show that deletion of spt4 increases TC‐NER in rad26 cells but does not affect repair in RAD26 + cells, regardless of the presence of Rpb9. Spt4 protects Spt5 from degradation and enhances the association of Spt5 with Pol II. Overexpression of Spt5 restores the UV sensitivity and partially suppressed NER activity. Moreover, TCR rates in rad26 cells are inversely correlated with the level of Spt5 associated with Pol II. Our results suggest that Spt4 and Spt5 cooperatively suppress TC‐NER only in the absence of Rad26. By binding to Pol II, Spt5 plays a more direct role in the suppression, whereas Spt4 is indirectly involved in the suppression by stabilizing Spt5 and by enhancing the binding of Spt5 to Pol II. This study was supported by NIH grant ES012718 and NSF grant MCB‐0745229.