title: YphC and YsxC GTPases assist the maturation of the central protuberance, GTPase associated region and functional core of the 50S ribosomal subunit.
abstract: YphC and YsxC are GTPases in Bacillus subtilis that facilitate the assembly of the 50S ribosomal subunit, however their roles in this process are still uncharacterized. To explore their function, we used strains in which the only copy of the yphC or ysxC genes were under the control of an inducible promoter. Under depletion conditions, they accumulated incomplete ribosomal subunits that we named 45SYphC and 44.5SYsxC particles. Quantitative mass spectrometry analysis and the 5-6 Å resolution cryo-EM maps of the 45SYphC and 44.5SYsxC particles revealed that the two GTPases participate in the maturation of the central protuberance, GTPase associated region and key RNA helices in the A, P and E functional sites of the 50S subunit. We observed that YphC and YsxC bind specifically to the two immature particles, suggesting that they represent either on-pathway intermediates or that their structure has not significantly diverged from that of the actual substrate. These results describe the nature of these immature particles, a widely used tool to study the assembly process of the ribosome. They also provide the first insights into the function of YphC and YsxC in 50S subunit assembly and are consistent with this process occurring through multiple parallel pathways, as it has been described for the 30S subunit.
authors.affiliation: Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S4K1, Canada M.G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario L8S4K1, Canada.
authors.forename: Xiaodan
authors.initials: X
authors.lastname: Ni
authors.affiliation: Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: Joseph H
authors.initials: JH
authors.lastname: Davis
authors.affiliation: Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Nikhil
authors.initials: N
authors.lastname: Jain
authors.affiliation: Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S4K1, Canada M.G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario L8S4K1, Canada.
authors.forename: Aida
authors.initials: A
authors.lastname: Razi
authors.affiliation: Molecular Structure and Function Program, The Hospital for Sick Children,Toronto, Ontario M5G 0A4, Canada.
authors.forename: Samir
authors.initials: S
authors.lastname: Benlekbir
authors.affiliation: Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S4K1, Canada M.G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario L8S4K1, Canada.
authors.forename: Andrew G
authors.initials: AG
authors.lastname: McArthur
authors.affiliation: Molecular Structure and Function Program, The Hospital for Sick Children,Toronto, Ontario M5G 0A4, Canada Department of Biochemistry, University of Toronto, Toronto, Ontario M5S 1A8, Canada Department of Medical Biophysics, University of Toronto, Toronto, Ontario M5G 1L7, Canada.
authors.forename: John L
authors.initials: JL
authors.lastname: Rubinstein
authors.affiliation: Department of Molecular Virology and Microbiology, Baylor College of Medicine, Houston, TX 77030, USA Center for Metagenomics and Microbiome Research, Baylor College of Medicine, Houston, TX 77030, USA.
authors.forename: Robert A
authors.initials: RA
authors.lastname: Britton
authors.affiliation: Department of Molecular Biology, The Scripps Research Institute, La Jolla, CA 92037, USA Department of Chemistry and The Skaggs Institute for Chemical Biology, The Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: James R
authors.initials: JR
authors.lastname: Williamson
authors.affiliation: Department of Biochemistry and Biomedical Sciences, McMaster University, Hamilton, Ontario L8S4K1, Canada M.G. DeGroote Institute for Infectious Diseases Research, McMaster University, Hamilton, Ontario L8S4K1, Canada ortegaj@mcmaster.ca.
authors.forename: Joaquin
authors.initials: J
authors.lastname: Ortega
mesh_terms: D001426:Bacterial Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D020285:Cryoelectron Microscopy; D020558:GTP Phosphohydrolases / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D007700:Kinetics; D013058:Mass Spectrometry; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D021122:Protein Subunits / Q000378:metabolism; D012269:Ribosomal Proteins / Q000737:chemistry / Q000378:metabolism* / Q000648:ultrastructure; D054681:Ribosome Subunits, Large, Bacterial / Q000378:metabolism* / Q000648:ultrastructure
chemical_list: D001426:Bacterial Proteins; D021122:Protein Subunits; D012269:Ribosomal Proteins; D020558:GTP Phosphohydrolases