title: Intrinsic flexibility of ubiquitin on proliferating cell nuclear antigen (PCNA) in translesion synthesis.
abstract: Ubiquitin conjugation provides a crucial signaling role in hundreds of cellular pathways; however, a structural understanding of ubiquitinated substrates is lacking. One important substrate is monoubiquitinated PCNA (PCNA-Ub), which signals for recruitment of damage-tolerant polymerases in the translesion synthesis (TLS) pathway of DNA damage avoidance. We use a novel and efficient enzymatic method to produce PCNA-Ub at high yield with a native isopeptide bond and study its Usp1/UAF1-dependent deconjugation. In solution we find that the ubiquitin moiety is flexible relative to the PCNA, with its hydrophobic patch mostly accessible for recruitment of TLS polymerases, which promotes the interaction with polymerase η. The studies are a prototype for the nature of the ubiquitin modification.
authors.affiliation: Division of Biochemistry and Center for Biomedical Genetics, The Netherlands Cancer Institute, Plesmanlaan 121, 1066 CX Amsterdam, The Netherlands. r.hibbert@nki.nl
authors.forename: Richard G
authors.initials: RG
authors.lastname: Hibbert
authors.forename: Titia K
authors.initials: TK
authors.lastname: Sixma
mesh_terms: D001703:Biophysics / Q000379:methods; D002850:Chromatography, Gel; D004249:DNA Damage; D004260:DNA Repair; D004261:DNA Replication; D004259:DNA-Directed DNA Polymerase / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008027:Light; D009682:Magnetic Resonance Spectroscopy / Q000379:methods; D008958:Models, Molecular; D018809:Proliferating Cell Nuclear Antigen / Q000737:chemistry* / Q000378:metabolism; D011487:Protein Conformation; D011499:Protein Processing, Post-Translational; D012542:Scattering, Radiation; D053838:Scattering, Small Angle; D015398:Signal Transduction; D025801:Ubiquitin / Q000737:chemistry*; D000099270:Y-Family DNA Polymerases
chemical_list: D004259:DNA-Directed DNA Polymerase; D018809:Proliferating Cell Nuclear Antigen; D025801:Ubiquitin; C112338:Rad30 protein; D000099270:Y-Family DNA Polymerases