We have identified carbon catabolite repression (CCR) as a regulator of amino acid permeases in Saccharomyces cerevisiae, elucidated the permeases regulated by CCR and also identified the mechanisms involved in amino acid permease regulation by CCR. Transport of L-arginine and L-leucine was increased by ~10-25 fold in yeast grown in carbon sources alternate to glucose, indicating regulation by CCR. In wild type (WT) yeast the uptake (pmol/10(6) cells/h), in glucose vs galactose medium, of L-[(14)C]arginine was (0.24 +/- 0.04 vs 6.11 +/- 0.42) and L-[(14)C]leucine was (0.30 +/- 0.02 vs 3.60 +/- 0.50). The increase in amino acid uptake was maintained when galactose was replaced with glycerol. Deletion of gap1delta and agp1delta from the WT strain did not alter CCR induced increase in L-leucine uptake; however, deletion of further amino acid permeases reduced the increase in L-leucine uptake in the following manner: 36%, gnp1delta , 62% (bap2delta ) 83% (delta (bap2-tat1)). Direct-immunofluorescence showed large increases in the expression of Gnp1 and Bap2 proteins when grown in galactose compared to glucose medium. By extending the functional genomic approach to include major nutritional transducers of CCR in yeast, we concluded that SNF/MIG, GCN or PSK pathways were not involved in the regulation of amino acid permeases by CCR. Strikingly, deletion of TOR1, which regulates cellular response to changes in nitrogen availability, from the WT strain abolished the CCR induced amino acid uptake. Our results provide novel insights into the regulation of yeast amino acid permeases and signalling mechanisms involved in this regulation.
|Evidence ID||Analyze ID||Interactor||Interactor Systematic Name||Interactor||Interactor Systematic Name||Type||Assay||Annotation||Action||Modification||Phenotype||Source||Reference||Note|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Gene Ontology Term||Gene Ontology Term ID||Qualifier||Aspect||Method||Evidence||Source||Assigned On||Reference||Annotation Extension|
|Evidence ID||Analyze ID||Gene||Gene Systematic Name||Phenotype||Experiment Type||Experiment Type Category||Mutant Information||Strain Background||Chemical||Details||Reference|
|Evidence ID||Analyze ID||Regulator||Regulator Systematic Name||Target||Target Systematic Name||Experiment||Conditions||Strain||Source||Reference|