title: Structural snapshot of cytoplasmic pre-60S ribosomal particles bound by Nmd3, Lsg1, Tif6 and Reh1.
abstract: A key step in ribosome biogenesis is the nuclear export of pre-ribosomal particles. Nmd3, a highly conserved protein in eukaryotes, is a specific adaptor required for the export of pre-60S particles. Here we used cryo-electron microscopy (cryo-EM) to characterize Saccharomyces cerevisiae pre-60S particles purified with epitope-tagged Nmd3. Our structural analysis indicates that these particles belong to a specific late stage of cytoplasmic pre-60S maturation in which ribosomal proteins uL16, uL10, uL11, eL40 and eL41 are deficient, but ribosome assembly factors Nmd3, Lsg1, Tif6 and Reh1 are present. Nmd3 and Lsg1 are located near the peptidyl-transferase center (PTC). In particular, Nmd3 recognizes the PTC in its near-mature conformation. In contrast, Reh1 is anchored to the exit of the polypeptide tunnel, with its C terminus inserted into the tunnel. These findings pinpoint a structural checkpoint role for Nmd3 in PTC assembly, and provide information about functional and mechanistic roles of these assembly factors in the maturation of the 60S ribosomal subunit.
authors.affiliation: Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Chengying
authors.initials: C
authors.lastname: Ma
authors.affiliation: Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Shan
authors.initials: S
authors.lastname: Wu
authors.affiliation: Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China.
authors.forename: Ningning
authors.initials: N
authors.lastname: Li
authors.affiliation: Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Yan
authors.initials: Y
authors.lastname: Chen
authors.affiliation: Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Kaige
authors.initials: K
authors.lastname: Yan
authors.affiliation: Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Zhifei
authors.initials: Z
authors.lastname: Li
authors.affiliation: Peking-Tsinghua Center for Life Sciences, School of Life Sciences, Peking University, Beijing, China.
authors.forename: Lvqin
authors.initials: L
authors.lastname: Zheng
authors.affiliation: Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Jianlin
authors.initials: J
authors.lastname: Lei
authors.affiliation: Department of Biological Sciences, Carnegie Mellon University, Pittsburgh, Pennsylvania, USA.
authors.forename: John L
authors.initials: JL
authors.lastname: Woolford
authors.affiliation: Ministry of Education Key Laboratory of Protein Sciences, Beijing Advanced Innovation Center for Structural Biology, School of Life Sciences, Tsinghua University, Beijing, China.
authors.forename: Ning
authors.initials: N
authors.lastname: Gao
mesh_terms: D003593:Cytoplasm / Q000378:metabolism* / Q000648:ultrastructure; D008958:Models, Molecular; D010455:Peptides / Q000737:chemistry / Q000378:metabolism; D010458:Peptidyl Transferases / Q000378:metabolism; D011485:Protein Binding; D000072417:Protein Domains; D012335:RNA, Ribosomal / Q000737:chemistry / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism; D054683:Ribosome Subunits, Large, Eukaryotic / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D012441:Saccharomyces cerevisiae / Q000378:metabolism* / Q000648:ultrastructure; D029701:Saccharomyces cerevisiae Proteins / Q000737:chemistry / Q000378:metabolism*
chemical_list: D010455:Peptides; D012335:RNA, Ribosomal; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins; C065039:RNA, ribosomal, 25S; D010458:Peptidyl Transferases