Figure 5.

GCN2-dependent effect upon Arg depletion is linked to nitrogen metabolism. (A) Simplified schematic of nitrogen metabolism. Ornithine is not only necessary for completion of the urea cycle but is necessary for polyamine biosynthesis. The mitochondrion compartment is shown as a blue oval. (B) Growth curve of gcn2Δ strain in complete media, lacking arginine, and lacking arginine supplemented with ornithine, citrulline and/or polyamines. (C) Heatmap of the wild type and gcn2Δ strains after depletion of arginine and supplementation with 2 mg/ml ornithine. Arrows indicate tRNA^Arg isoacceptors. (D) Histogram of relative charging level before and after Arg-depletion/Orn supplementation for the gcn2Δ strain. Inset shows the charging levels of the tRNA^Arg isoacceptors in the absence and presence of ornithine.