Figure 9.

Impairment of PRPP utilization via the purine de novo pathway reveals that PRPP is limiting for nucleotide synthesis.A, B, and D–H, Wild-type (FY4) and ade4Δ (Y12258) yeast strains were exponentially grown for 24 h in SDcasaWAU liquid medium. Cells were then harvested by filtration and grown for three more hours in SDcasaWU liquid medium supplemented (+) or not (−) with adenine before metabolite extraction, separation, and quantification. C, and I–N, the wild-type strain (Y11418) was transformed with an empty vector (pCM189) or a plasmid carrying the ADE4 hyperactive R328K dominant mutant (p2048). Transformants were exponentially grown for 24 h in SDcasaWA medium before extraction, separation, and quantification of metabolites. D–N, metabolite measurements were performed on four independent cultures and numbers correspond to the p-values calculated from a Welch’s unpaired t test.