Figure 5.

Schematic representation of putative lipid pathways in phagosomal maturation. As phagosomes mature, their ceramide content increases due to the activity of CerS2, which is found enriched on EPs. Two other cryptic activities are postulated in this scheme based on our lipidomics results. The first, an unknown fatty acyl-CoA transferase, which converts PC and/or PE to generate fatty acyl-CoA, which is eventually converted to ceramide, by the N-acylation activity of CerS2. The second is a PUFA-specific phospholipase activity, which converts PUFA containing PC and/or PE lipids into free PUFAs that are found enriched on LPs.