title: Mammalian Elongin A complex mediates DNA-damage-induced ubiquitylation and degradation of Rpb1.
abstract: The Elongin complex stimulates the rate of transcription elongation by RNA polymerase II (pol II) by suppressing transient pausing of the pol II at many sites along the DNA. Elongin is composed of a transcriptionally active A subunit and two small regulatory B and C subunits, which can form an isolable Elongin BC subcomplex. Here, we have shown that both the ubiquitylation and proteasomal degradation of the largest subunit of pol II (Rpb1) following UV-irradiation are significantly suppressed in Elongin A-deficient cells; however, in both cases suppression is rescued by transfection of wild-type Elongin A. Moreover, we have demonstrated that the Elongin A-Elongin BC complex is capable of assembling with the Cul5/Rbx2 module, and that this hetero-pentamer complex efficiently ubiquitylates Rpb1 in vitro. Mechanistic studies indicate that colocalization of Elongin A and Cul5 in cells and the interaction of Elongin A with the Ser5-phosphorylated form of Rpb1 are strongly enhanced following UV-irradiation. Taken together, our results suggest that mammalian Elongin A is directly involved in ubiquitylation and degradation of Rpb1 following DNA damage.
authors.affiliation: Department of Functional Genomics, Kochi Medical School, Kohasu, Oko-cho, Nankoku City, Kochi, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Yasukawa
authors.forename: Takumi
authors.initials: T
authors.lastname: Kamura
authors.forename: Shigetaka
authors.initials: S
authors.lastname: Kitajima
authors.forename: Ronald C
authors.initials: RC
authors.lastname: Conaway
authors.forename: Joan W
authors.initials: JW
authors.lastname: Conaway
authors.forename: Teijiro
authors.initials: T
authors.lastname: Aso
mesh_terms: D000818:Animals; D002460:Cell Line; D044842:Cullin Proteins / Q000378:metabolism; D004249:DNA Damage; D000075065:Elongin; D006801:Humans; D011485:Protein Binding; D012319:RNA Polymerase II / Q000378:metabolism*; D014157:Transcription Factors / Q000378:metabolism*; D054875:Ubiquitination; D014466:Ultraviolet Rays
chemical_list: D044842:Cullin Proteins; C000616397:ELOA protein, human; C000616403:Eloa protein, mouse; D000075065:Elongin; D014157:Transcription Factors; C531145:cullin5 protein, mouse; D012319:RNA Polymerase II; C522173:Rpb1 protein, mouse