title: Novel stress-responsive genes EMG1 and NOP14 encode conserved, interacting proteins required for 40S ribosome biogenesis.
abstract: Under stressful conditions organisms adjust the synthesis, processing, and trafficking of molecules to allow survival from and recovery after stress. In baker's yeast Saccharomyces cerevisiae, the cellular production of ribosomes is tightly matched with environmental conditions and nutrient availability through coordinate transcriptional regulation of genes involved in ribosome biogenesis. On the basis of stress-responsive gene expression and functional studies, we have identified a novel, evolutionarily conserved gene, EMG1, that has similar stress-responsive gene expression patterns as ribosomal protein genes and is required for the biogenesis of the 40S ribosomal subunit. The Emg1 protein is distributed throughout the cell; however, its nuclear localization depends on physical interaction with a newly characterized nucleolar protein, Nop14. Yeast depleted of Nop14 or harboring a temperature-sensitive allele of emg1 have selectively reduced levels of the 20S pre-rRNA and mature18S rRNA and diminished cellular levels of the 40S ribosomal subunit. Neither Emg1 nor Nop14 contain any characterized functional motifs; however, isolation and functional analyses of mammalian orthologues of Emg1 and Nop14 suggest that these proteins are functionally conserved among eukaryotes. We conclude that Emg1 and Nop14 are novel proteins whose interaction is required for the maturation of the 18S rRNA and for 40S ribosome production.
authors.affiliation: Department of Biological Chemistry, The University of Michigan Medical School, Ann Arbor, Michigan 48109-0606, USA.
authors.forename: P C
authors.initials: PC
authors.lastname: Liu
authors.forename: D J
authors.initials: DJ
authors.lastname: Thiele
mesh_terms: D000595:Amino Acid Sequence; D000617:Aminoglycosides; D000818:Animals; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000235:genetics* / Q000378:metabolism; D005800:Genes, Fungal / Q000502:physiology*; D018869:Heat-Shock Response; D006361:Heating; D006801:Humans; D051379:Mice; D008856:Microscopy, Fluorescence / Q000379:methods; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000235:genetics* / Q000378:metabolism; D012323:RNA Processing, Post-Transcriptional; D012331:RNA, Fungal / Q000378:metabolism*; D012333:RNA, Messenger / Q000378:metabolism*; D012337:RNA, Ribosomal, 18S / Q000378:metabolism; D012269:Ribosomal Proteins / Q000235:genetics* / Q000378:metabolism; D012270:Ribosomes / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D029701:Saccharomyces cerevisiae Proteins / Q000235:genetics* / Q000378:metabolism; D017386:Sequence Homology, Amino Acid
chemical_list: D000617:Aminoglycosides; D000900:Anti-Bacterial Agents; C444457:EMG1 protein, S cerevisiae; D005656:Fungal Proteins; C444458:NOP14 protein, S cerevisiae; D009687:Nuclear Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D012337:RNA, Ribosomal, 18S; D012269:Ribosomal Proteins; D029701:Saccharomyces cerevisiae Proteins