title: Integrative structural analysis of the UTPB complex, an early assembly factor for eukaryotic small ribosomal subunits.
abstract: Ribosome assembly is an essential and conserved cellular process in eukaryotes that requires numerous assembly factors. The six-subunit UTPB complex is an essential component of the 90S precursor of the small ribosomal subunit. Here, we analyzed the molecular architecture of UTPB using an integrative structural biology approach. We mapped the major interactions that associate each of six UTPB proteins. Crystallographic studies showed that Utp1, Utp21, Utp12 and Utp13 are evolutionarily related and form a dimer of dimers (Utp1-Utp21, Utp12-Utp13) through their homologous helical C-terminal domains. Molecular docking with crosslinking restraints showed that the WD domains of Utp12 and Utp13 are associated, as are the WD domains of Utp1, Utp21 and Utp18. Electron microscopy images of the entire UTPB complex revealed that it predominantly adopts elongated conformations and possesses internal flexibility. We also determined crystal structures of the WD domain of Utp18 and the HAT and deviant HAT domains of Utp6. A structural model of UTPB was derived based on these data.
authors.affiliation: National Institute of Biological Sciences, Beijing 102206, China.
authors.forename: Cheng
authors.initials: C
authors.lastname: Zhang
authors.affiliation: National Institute of Biological Sciences, Beijing 102206, China Peking University-Tsinghua University-National Institute of Biological Sciences Joint Graduate Program, School of Life Sciences, Tsinghua University, Beijing 100084, China Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China Beijing Key Laboratory of Noncoding RNA, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Qi
authors.initials: Q
authors.lastname: Sun
authors.affiliation: Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China Beijing Key Laboratory of Noncoding RNA, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China.
authors.forename: Rongchang
authors.initials: R
authors.lastname: Chen
authors.affiliation: National Institute of Biological Sciences, Beijing 102206, China.
authors.forename: Xining
authors.initials: X
authors.lastname: Chen
authors.affiliation: National Institute of Biological Sciences, Beijing 102206, China.
authors.forename: Jinzhong
authors.initials: J
authors.lastname: Lin
authors.affiliation: Key Laboratory of RNA Biology, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China Beijing Key Laboratory of Noncoding RNA, CAS Center for Excellence in Biomacromolecules, Institute of Biophysics, Chinese Academy of Sciences, Beijing 100101, China yekeqiong@ibp.ac.cn.
authors.forename: Keqiong
authors.identifier: 0000-0001-6169-7049
authors.initials: K
authors.lastname: Ye
mesh_terms: D003432:Cross-Linking Reagents / Q000737:chemistry; D018360:Crystallography, X-Ray; D008854:Microscopy, Electron; D062105:Molecular Docking Simulation; D009687:Nuclear Proteins / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D000072417:Protein Domains; D025941:Protein Interaction Mapping; D016601:RNA-Binding Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism / Q000648:ultrastructure; D054682:Ribosome Subunits, Small, Eukaryotic / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D012270:Ribosomes / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D003432:Cross-Linking Reagents; D009687:Nuclear Proteins; D016601:RNA-Binding Proteins; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; C532249:Utp1 protein, S cerevisiae; C000620219:Utp12 protein, S cerevisiae; C000620220:Utp13 protein, S cerevisiae; C000602833:Utp18 protein, S cerevisiae; C531337:Utp21 protein, S cerevisiae; C532747:Utp6 protein, S cerevisiae