title: In vivo functional characterization of the Saccharomyces cerevisiae 60S biogenesis GTPase Nog1.
abstract: The Saccharomyces cerevisiae Nog1 GTPase is critical for assembly of the large ribosomal subunit. Mutations in conserved residues in the GTP-binding pocket cause defects in cell growth and 60S ribosome assembly but mutant proteins retain their ability to associate with the pre-60S. Association of Nog1 with the pre-60S is independent of guanine nucleotide added to cell extracts. Thus, it appears that nucleotide occupancy does not substantially affect Nog1 association with pre-60S particles. Somewhat surprisingly, neither of the conserved threonines in the G2 motif of the GTPase domain is essential for Nog1 function. Neither the steady-state rRNA levels nor the protein composition (as determined by isobaric labeling and identification by mass spectrometry of peptides) of the pre-60S particles in the nog1P176V mutant are grossly perturbed, although levels of four proteins (Nog1, Nop2, Nop15, and Tif6) are modestly reduced in pre-60S particles isolated from the mutant. Deletion analysis revealed that the C-terminal 168 amino acids are not required for function; however, the N-terminal 126 amino acids are required. Optimal association with pre-60S particles requires sequences between amino acids 347-456. Several conserved charge-to-alanine substitutions outside the GTPase domain display modest growth phenotypes indicating that these residues are not critical for function.
authors: Department of Molecular, Cellular and Developmental Biology, University of Michigan, 830 North University Avenue, Ann Arbor, MI 48109, USA.
authors: Jennifer L
authors: JL
authors: Fuentes
authors: Kaustuv
authors: K
authors: Datta
authors: Susan M
authors: SM
authors: Sullivan
authors: Angela
authors: A
authors: Walker
authors: Janine R
authors: JR
authors: Maddock
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D020558:GTP Phosphohydrolases / Q000378:metabolism*; D019204:GTP-Binding Proteins / Q000378:metabolism*; D015966:Gene Expression Regulation, Fungal; D006160:Guanosine Triphosphate / Q000378:metabolism; D006801:Humans; D013058:Mass Spectrometry; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D009711:Nucleotides / Q000737:chemistry; D017434:Protein Structure, Tertiary; D012335:RNA, Ribosomal / Q000737:chemistry; D012270:Ribosomes / Q000378:metabolism; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins / Q000378:metabolism*; D017386:Sequence Homology, Amino Acid
chemical_list: C475027:NOG1 protein, S cerevisiae; D009687:Nuclear Proteins; D009711:Nucleotides; D012335:RNA, Ribosomal; D029701:Saccharomyces cerevisiae Proteins; D006160:Guanosine Triphosphate; D020558:GTP Phosphohydrolases; D019204:GTP-Binding Proteins