title: Structural basis for the recognition of N-end rule substrates by the UBR box of ubiquitin ligases.
abstract: The N-end rule pathway is a regulated proteolytic system that targets proteins containing destabilizing N-terminal residues (N-degrons) for ubiquitination and proteasomal degradation in eukaryotes. The N-degrons of type 1 substrates contain an N-terminal basic residue that is recognized by the UBR box domain of the E3 ubiquitin ligase UBR1. We describe structures of the UBR box of Saccharomyces cerevisiae UBR1 alone and in complex with N-degron peptides, including that of the cohesin subunit Scc1, which is cleaved and targeted for degradation at the metaphase-anaphase transition. The structures reveal a previously unknown protein fold that is stabilized by a novel binuclear zinc center. N-terminal arginine, lysine or histidine side chains of the N-degron are coordinated in a multispecific binding pocket. Unexpectedly, the structures together with our in vitro biochemical and in vivo pulse-chase analyses reveal a previously unknown modulation of binding specificity by the residue at position 2 of the N-degron.
authors.affiliation: School of Life Sciences and Biotechnology, Korea University, Anam-Dong, Korea.
authors.forename: Woo Suk
authors.initials: WS
authors.lastname: Choi
authors.forename: Byung-Cheon
authors.initials: BC
authors.lastname: Jeong
authors.forename: Yoo Jin
authors.initials: YJ
authors.lastname: Joo
authors.forename: Myeong-Ryeol
authors.initials: MR
authors.lastname: Lee
authors.forename: Joon
authors.initials: J
authors.lastname: Kim
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Eck
authors.forename: Hyun Kyu
authors.initials: HK
authors.lastname: Song
mesh_terms: D000595:Amino Acid Sequence; D019943:Amino Acid Substitution; D001120:Arginine / Q000737:chemistry; D018797:Cell Cycle Proteins / Q000737:chemistry / Q000378:metabolism; D002868:Chromosomal Proteins, Non-Histone / Q000737:chemistry / Q000378:metabolism; D018360:Crystallography, X-Ray; D006639:Histidine / Q000737:chemistry; D057927:Hydrophobic and Hydrophilic Interactions; D008239:Lysine / Q000737:chemistry; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009842:Oligopeptides / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D025941:Protein Interaction Mapping; D011499:Protein Processing, Post-Translational; D017434:Protein Structure, Tertiary; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity; D025801:Ubiquitin / Q000378:metabolism; D044767:Ubiquitin-Protein Ligases / Q000737:chemistry / Q000378:metabolism*; D016335:Zinc Fingers / Q000502:physiology
chemical_list: D018797:Cell Cycle Proteins; D002868:Chromosomal Proteins, Non-Histone; C490529:MCD1 protein, S cerevisiae; D009842:Oligopeptides; D029701:Saccharomyces cerevisiae Proteins; D025801:Ubiquitin; D006639:Histidine; D001120:Arginine; C066066:UBR1 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; D008239:Lysine