Fig. 2.

Characterization of the PUL genes. (A) Cells grown on defined medium produced a red pigment when the complete PULcherrimin pathway was present, but they lacked pigmentation when key genes were deleted. Complementation tests can be found in SI Appendix, Fig. S2. (B) Representative growth curves of individual pul mutants in PA-treated medium, where cells must uptake pulcherrimin to grow. Complementation tests can be found in SI Appendix, Fig. S5B. (C) Summary table of pulcherrimin production and growth in PA-treated medium. (D) Model of the putative roles of the PUL genes in siderophore production and reuptake based on our genetic data and previous biochemistry data (18–20); however, the yeast proteins currently lack direct biochemical assays. Blue lines represent regulation of PUL gene expression by Pul4.