title: The C-terminal repeat domain of Spt5 plays an important role in suppression of Rad26-independent transcription coupled repair.
abstract: In eukaryotic cells, transcription coupled nucleotide excision repair (TCR) is believed to be initiated by RNA polymerase II (Pol II) stalled at a lesion in the transcribed strand of a gene. Rad26, the yeast homolog of the human Cockayne syndrome group B (CSB) protein, plays an important role in TCR. Spt4, a transcription elongation factor that forms a complex with Spt5, has been shown to suppress TCR in rad26Delta cells. Here we present evidence that Spt4 indirectly suppresses Rad26-independent TCR by protecting Spt5 from degradation and stabilizing the interaction of Spt5 with Pol II. We further found that the C-terminal repeat (CTR) domain of Spt5, which is dispensable for cell viability and is not involved in interactions with Spt4 and Pol II, plays an important role in the suppression. The Spt5 CTR is phosphorylated by the Bur kinase. Inactivation of the Bur kinase partially alleviates TCR in rad26Delta cells. We propose that the Spt5 CTR suppresses Rad26-independent TCR by serving as a platform for assembly of a multiple protein suppressor complex that is associated with Pol II. Phosphorylation of the Spt5 CTR by the Bur kinase may facilitate the assembly of the suppressor complex.
authors.affiliation: Department of Comparative Biomedical Sciences, Louisiana State University, Baton Rouge, Louisiana 70803, USA.
authors.forename: Baojin
authors.initials: B
authors.lastname: Ding
authors.forename: Danielle
authors.initials: D
authors.lastname: LeJeune
authors.forename: Shisheng
authors.initials: S
authors.lastname: Li
mesh_terms: D000251:Adenosine Triphosphatases / Q000235:genetics / Q000378:metabolism*; D002868:Chromosomal Proteins, Non-Histone / Q000235:genetics / Q000378:metabolism*; D004265:DNA Helicases / Q000235:genetics / Q000378:metabolism; D004260:DNA Repair / Q000502:physiology*; D045643:DNA Repair Enzymes / Q000235:genetics / Q000378:metabolism; D006801:Humans; D009687:Nuclear Proteins / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation / Q000502:physiology; D000075223:Poly-ADP-Ribose Binding Proteins; D017434:Protein Structure, Tertiary / Q000502:physiology; D012319:RNA Polymerase II / Q000235:genetics / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics / Q000378:metabolism*; D014158:Transcription, Genetic / Q000502:physiology*; D035602:Transcriptional Elongation Factors / Q000235:genetics / Q000378:metabolism*
chemical_list: D002868:Chromosomal Proteins, Non-Histone; D009687:Nuclear Proteins; D000075223:Poly-ADP-Ribose Binding Proteins; C080991:SPT4 protein, S cerevisiae; D029701:Saccharomyces cerevisiae Proteins; D035602:Transcriptional Elongation Factors; C069940:SPT5 transcriptional elongation factor; D012319:RNA Polymerase II; D000251:Adenosine Triphosphatases; C465758:RAD26 protein, S cerevisiae; D004265:DNA Helicases; C078673:ERCC6 protein, human; D045643:DNA Repair Enzymes