Figure 2.

Functional complementation of the yeast phosphoribosyl aminoimidazole succinocarboxamide synthetase by the Xenopus laevis ortholog paics1.L. (a). Simplified scheme of the yeast purine pathway. (b). Yeast wild-type and knock-out mutant (ade1Δ) strains were either transformed with a plasmid allowing expression of the yeast (ADE1 Sc) or the Xenopus laevis (paics 1.L) amino imidazole succinocarboxamide synthetase encoded gene, or with the empty vector (None). Serial dilutions (1/10) of transformants were dropped on SDCASAW medium to score the ability of the yeast and xenopus genes to complement the ade1 mutant auxotrophy observed in the absence of external purine source. A medium supplemented with adenine was used as a viability control of transformants and images were obtained after 34 h of growth at 37 °C.