FIG 3.

C. albicans Gnp2 is essential for proline uptake. (A) C. albicans cultures grown overnight were spotted onto agar plates containing the indicated C sources supplemented with ammonium sulfate. Plates were incubated at 37°C for 2 days (GABA) or 3 days (proline). (B) MS-based quantification of extracellular proline in spent medium containing proline as the sole carbon source (YNB, ammonium sulfate, 10 mM proline [pH 4.5]) after 6 h of incubation of the indicated strains. The proline concentration was normalized to an internal standard (10 mM 13C5 l-proline). Measurement of the medium control was performed in technical triplicates, and measurement of the spent medium was performed in five biological replicates. Significance was tested via one-way ANOVA with the medium control as the reference, indicated by asterisks (***, P < 0.001; ****, P < 0.0001).