A highly conserved mechanism of regulated ribosome stalling mediated by fungal arginine attenuator peptides that appears independent of the charging status of arginyl-tRNAs.
The Arg attenuator peptide (AAP) is an evolutionarily conserved peptide involved in Arg-specific negative translational control. It is encoded as an upstream open reading frame (uORF) in fungal mRNAs specifying the small subunit of Arg-specific carbamoyl phosphate synthetase. We examined the functions of the Saccharomyces cerevisiae CPA1 and Neurospora crassa arg-2 AAPs using translation extracts from S. cerevisiae, N. crassa, and wheat germ. Synthetic RNA containing AAP and firefly luciferase (LUC) sequences were used to program translation; analyses of LUC activity indicated that the AAPs conferred Arg-specific negative regulation in each system. The AAPs functioned either as uORFs or fused in-frame at the N terminus of LUC. Mutant AAPs lacking function in vivo did not function in vitro. Therefore, trans-acting factors conferring AAP-mediated regulation are in both fungal and plant systems. Analyses of ribosome stalling in the fungal extracts by primer extension inhibition (toeprint) assays showed that these AAPs acted similarly to stall ribosomes in the region immediately distal to the AAP coding region in response to Arg. The regulatory effect increased as the Arg concentration increased; all of the arginyl-tRNAs examined appeared maximally charged at low Arg concentrations. Therefore, AAP-mediated Arg-specific regulation appeared independent of the charging status of arginyl-tRNA.
Wang
Z
Z
Department of Biochemistry, Oregon Graduate Institute of Science and Technology, Beaverton, Oregon 97006-8921, USA.
Gaba
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Sachs
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MS
D000595:Amino Acid Sequence; D001483:Base Sequence; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing); D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor / Q000737:chemistry / Q000502:physiology*; D002474:Cell-Free System; D017124:Conserved Sequence; D005656:Fungal Proteins / Q000737:chemistry / Q000502:physiology*; D008156:Luciferases / Q000235:genetics; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000502:physiology*; D014176:Protein Biosynthesis; D012347:RNA, Transfer, Arg / Q000235:genetics / Q000378:metabolism*; D012270:Ribosomes / Q000502:physiology*; D012441:Saccharomyces cerevisiae / Q000378:metabolism*; D029701:Saccharomyces cerevisiae Proteins; D017386:Sequence Homology, Amino Acid
D005656:Fungal Proteins; D010446:Peptide Fragments; D012347:RNA, Transfer, Arg; D029701:Saccharomyces cerevisiae Proteins; C116079:arginine attenuator peptide; D008156:Luciferases; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor; C403521:CPA1 protein, S cerevisiae; D002223:Carbamoyl-Phosphate Synthase (Glutamine-Hydrolyzing)