Fig. 2.

Genetic evidence for PfPSD-mediated phosphatidylserine decarboxylation, but not serine decarboxylation activity in vivo.

A. PfPSD is a functional PSD enzyme. WT and psd1Δpsd2Δdpl1Δ mutants harboring an empty vector (V), or vectors containing either the full-length PfPSD or its ortholog from P. knowlesi, PkPSD, were grown overnight in minimal medium containing ethanolamine. The strains were harvested by centrifugation in water, to remove medium, and spotted on SD solid media lacking, or containing 2 mM ethanolamine, at a cell density ranging between 10 and 10⁴ cells and incubated at 30°C for up to 9 days.

B. PfPSD does not catalyze serine decarboxylase activity. The yeast pss mutant strains harboring an empty vector (pBEVY) or pBEVY-PfPSD were spotted using serial fivefold dilutions starting with 3 × 10⁴ cells, on SD media lacking, or supplemented with 2 mM ethanolamine and incubated at 30°C for 2 days.