Translational regulation in response to changes in amino acid availability in Neurospora crassa.
We examined the regulation of Neurospora crassa arg-2 and cpc-1 in response to amino acid availability.arg-2 encodes the small subunit of arginine-specific carbamoyl phosphate synthetase; it is subject to unique negative regulation by Arg and is positively regulated in response to limitation for many different amino acids through a mechanism known as cross-pathway control. cpc-1 specifies a transcriptional activator important for crosspathway control. Expression of these genes was compared with that of the cytochrome oxidase subunit V gene, cox-5. Analyses of mRNA levels, polypeptide pulse-labeling results, and the distribution of mRNA in polysomes indicated that Arg-specific negative regulation of arg-2 affected the levels of both arg-2 mRNA and arg-2 mRNA translation. Negative translational effects on arg-2 and positive translational effects on cpc-1 were apparent soon after cells were provided with exogenous Arg. In cells limited for His, increased expression of arg-2 and cpc-1, and decreased expression of cox-5, also had translational and transcriptional components. The arg-2 and cpc-1 transcripts contain upstream open reading frames (uORFs), as do their Saccharomyces cerevisiae homologs CPA1 and GCN4. We examined the regulation of arg-2-lacZ reporter genes containing or lacking the uORF start codon; the capacity for arg-2 uORF translation appeared critical for controlling gene expression.
Luo
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Department of Chemistry, Biochemistry, and Molecular Biology, Oregon Graduate Institute of Science and Technology, Portland, Oregon 97291-1000, USA.
Freitag
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Sachs
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MS
D000640:Amitrole / Q000494:pharmacology; D001120:Arginine / Q000494:pharmacology; D001483:Base Sequence; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor; D018387:Codon, Initiator; D004268:DNA-Binding Proteins / Q000096:biosynthesis / Q000235:genetics*; D003576:Electron Transport Complex IV / Q000235:genetics; D005656:Fungal Proteins / Q000096:biosynthesis / Q000235:genetics*; D015966:Gene Expression Regulation, Fungal / Q000187:drug effects*; D005800:Genes, Fungal / Q000235:genetics; D006639:Histidine / Q000502:physiology; D006836:Hydro-Lyases / Q000037:antagonists & inhibitors; D008025:Ligases / Q000096:biosynthesis / Q000235:genetics*; D008969:Molecular Sequence Data; D009492:Neurospora crassa / Q000201:enzymology / Q000235:genetics*; D016366:Open Reading Frames / Q000235:genetics; D011132:Polyribosomes / Q000378:metabolism; D014176:Protein Biosynthesis / Q000187:drug effects*; D012331:RNA, Fungal / Q000096:biosynthesis; D012333:RNA, Messenger / Q000096:biosynthesis; D014158:Transcription, Genetic / Q000187:drug effects
D018387:Codon, Initiator; D004268:DNA-Binding Proteins; D005656:Fungal Proteins; D012331:RNA, Fungal; D012333:RNA, Messenger; D006639:Histidine; D001120:Arginine; D003576:Electron Transport Complex IV; D006836:Hydro-Lyases; D008025:Ligases; D019733:Carbon-Nitrogen Ligases with Glutamine as Amide-N-Donor; C064716:carbamoyl phosphate synthetase (arginine-specific); D000640:Amitrole