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	Mol. Cell May (2008); 30(4):498-506
Reversal of RNA polymerase II ubiquitylation by the ubiquitin protease Ubp3-
Kvint K, Uhler JP, Taschner MJ, Sigurdsson S, Erdjument-Bromage H, Tempst P, Svejstrup JQ
Cancer Research UK London Research Institute, Clare Hall Laboratories, Blanche Lane, South Mimms, Herts EN6 3LD, UK-
Abstract: The final outcome of protein polyubiquitylation is often proteasome-mediated proteolysis, meaning that "proofreading" of ubiquitylation by ubiquitin proteases -UBPs- is crucial- Transcriptional arrest can trigger ubiquitin-mediated proteolysis of RNA polymerase II -RNAPII- so a UBP reversing RNAPII ubiquitylation might be expected- Here, we show that Ubp3 deubiquitylates RNAPII in yeast- Genetic characterization of ubp3 cells is consistent with a role in elongation, and Ubp3 can be purified with RNAPII, Def1, and the elongation factors Spt5 and TFIIF- This Ubp3 complex deubiquitylates both mono- and polyubiquitylated RNAPII in vitro, and ubp3 cells have elevated levels of ubiquitylated RNAPII in vivo- Moreover, RNAPII is degraded faster in a ubp3 mutant after UV irradiation- Problems posed by damage-arrested RNAPII are thought to be resolved either by removing the damage or degrading the polymerase- In agreement with this, cells with compromised DNA repair are better equipped to survive UV damage when UPB3 is deleted-
[PUBMED: 18498751]