title: Molecular basis of Pirh2-mediated p53 ubiquitylation.
abstract: Pirh2 (p53-induced RING-H2 domain protein; also known as Rchy1) is an E3 ubiquitin ligase involved in a negative-feedback loop with p53. Using NMR spectroscopy, we show that Pirh2 is a unique cysteine-rich protein comprising three modular domains. The protein binds nine zinc ions using a variety of zinc coordination schemes, including a RING domain and a left-handed beta-spiral in which three zinc ions align three consecutive small beta-sheets in an interleaved fashion. We show that Pirh2-p53 interaction is dependent on the C-terminal zinc binding module of Pirh2, which binds to the tetramerization domain of p53. As a result, Pirh2 preferentially ubiquitylates the tetrameric form of p53 in vitro and in vivo, suggesting that Pirh2 regulates protein turnover of the transcriptionally active form of p53.
authors.affiliation: Ontario Cancer Institute and Department of Medical Biophysics, University of Toronto, Ontario M5G1L7, Canada.
authors.forename: Yi
authors.initials: Y
authors.lastname: Sheng
authors.forename: Rob C
authors.initials: RC
authors.lastname: Laister
authors.forename: Alexander
authors.initials: A
authors.lastname: Lemak
authors.forename: Bin
authors.initials: B
authors.lastname: Wu
authors.forename: Elizabeth
authors.initials: E
authors.lastname: Tai
authors.forename: Shili
authors.initials: S
authors.lastname: Duan
authors.forename: Jonathan
authors.initials: J
authors.lastname: Lukin
authors.forename: Maria
authors.initials: M
authors.lastname: Sunnerhagen
authors.forename: Sampath
authors.initials: S
authors.lastname: Srisailam
authors.forename: Murthy
authors.initials: M
authors.lastname: Karra
authors.forename: Sam
authors.initials: S
authors.lastname: Benchimol
authors.forename: Cheryl H
authors.initials: CH
authors.lastname: Arrowsmith
mesh_terms: D000595:Amino Acid Sequence; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011485:Protein Binding; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D025941:Protein Interaction Mapping; D017434:Protein Structure, Tertiary; D016415:Sequence Alignment; D016159:Tumor Suppressor Protein p53 / Q000378:metabolism*; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry* / Q000378:metabolism*; D054875:Ubiquitination
chemical_list: D016159:Tumor Suppressor Protein p53; C485369:RCHY1 protein, human; D044767:Ubiquitin-Protein Ligases