Impaired biosynthesis of the non-bilayer lipids phosphatidylethanolamine or cardiolipin does not affect peroxisome biogenesis and proliferation in Saccharomyces cerevisiae.

The non-bilayer forming lipids cardiolipin (CL) and phosphatidylethanolamine (PE) modulate membrane curvature, facilitate membrane fusion and affect the stability and function of membrane proteins. Yeast peroxisomal membranes contain significant amounts of CL and PE. We analysed the effect of CL deficiency and PE depletion on peroxisome biogenesis and proliferation in Saccharomyces cerevisiae. Our data indicate that deletion of CRD1, which encodes cardiolipin synthase, does not affect peroxisome biogenesis or abundance, both at peroxisome repressing (glucose) or inducing (oleate) growth conditions. Analysis of strains deficient in one of the three PE biosynthesis pathways (psd1, psd2 or the triple deletion strain eki1 cki1 dpl1) revealed that in all three strains peroxisome numbers were reduced upon growth of cells on oleic acid, whereas the psd1 strain also showed a reduction in peroxisome abundance upon growth on glucose. Because PE is an intermediate of the phosphatidylcholine (PC) biosynthesis pathway, PE depletion affects PC formation. PC however can be synthesized by an alternative pathway when choline is supplemented to the growth medium. Because the addition of choline resulted in suppression of the peroxisome phenotypes in phosphatidylserine decarboxylase mutant strains, we conclude that peroxisome biogenesis and proliferation are not crucially dependent on CL or PE.