PTR3, a novel gene mediating amino acid-inducible regulation of peptide transport in Saccharomyces cerevisiae.
We have isolated and characterized the Saccharomyces cerevisiae PTR3 gene by functional complementation of a mutant deficient for amino acid-inducible peptide transport. PTR3 is predicted to encode a protein of 678 amino acids that exhibits no similarity to any other protein in the database. Deletion of the PTR3 open reading frame pleiotropically reduced the sensitivity to toxic peptides and amino acid analogues. Initial rates of radiolabelled dipeptide uptake demonstrated that elimination of PTR3 resulted in the loss of amino acid-induced levels of peptide transport. PTR3 was required for amino acid-induced expression of PTR2, the gene encoding the dipeptide/tripeptide transport protein, but was not necessary for nitrogen catabolite repression of peptide import or PTR2 expression. It was determined that PTR3 also modulates expression of BAP2, the gene encoding the branched-amino acid permease. Furthermore, we present genetic evidence that suggests that PTR3 functions within a novel regulatory pathway that facilitates amino acid induction of the PTR system.
Department of Microbiology and University of Tennessee, Knoxville 37996-0845, USA.
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Barnes
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Lai
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Breslav
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Naider
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Becker
D026905:Amino Acid Transport Systems; D000596:Amino Acids; D001692:Biological Transport; D015152:Blotting, Northern; D002352:Carrier Proteins / Q000235:genetics / Q000502:physiology*; D015825:Chromosomes, Fungal; D004151:Dipeptides / Q000494:pharmacology; D004843:Epistasis, Genetic; D005656:Fungal Proteins / Q000235:genetics / Q000502:physiology*; D015870:Gene Expression; D005800:Genes, Fungal; D018398:Homeodomain Proteins / Q000235:genetics; D007930:Leucine; D008025:Ligases; D008565:Membrane Proteins / Q000235:genetics / Q000502:physiology*; D026901:Membrane Transport Proteins / Q000235:genetics; D010455:Peptides / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000187:drug effects / Q000235:genetics / Q000378:metabolism* / Q000502:physiology; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors / Q000235:genetics; D014316:Tritium; D044767:Ubiquitin-Protein Ligases
D026905:Amino Acid Transport Systems; D000596:Amino Acids; C097094:BAP2 protein, S cerevisiae; C090457:CUP9 protein, S cerevisiae; D002352:Carrier Proteins; D004151:Dipeptides; D005656:Fungal Proteins; D018398:Homeodomain Proteins; D008565:Membrane Proteins; D026901:Membrane Transport Proteins; C093495:PTR2 protein, S cerevisiae; C106976:PTR3 protein, S cerevisiae; D010455:Peptides; D029701:Saccharomyces cerevisiae Proteins; D014157:Transcription Factors; D014316:Tritium; C066066:UBR1 protein, S cerevisiae; D044767:Ubiquitin-Protein Ligases; D008025:Ligases; D007930:Leucine