Level of M(IP)2C sphingolipid affects plant defensin sensitivity, oxidative stress resistance and chronological life‐span in yeast

Abstract
The antifungal plant defensin DmAMP1 interacts with fungal sphingolipids of mannosyldiinositolphosphorylceramide (M(IP)2C) class. We screened a Saccharomyces cerevisiae transposon (Tn) mutant library against DmAMP1 and identified one DmAMP1‐resistant mutant with the Tn inserted in the M(IP)2C biosynthesis gene IPT1 (DmTn11) and one DmAMP1‐hypersensitive mutant with the Tn inserted in rDNA (HsTnII). However, tetrad analysis pointed to HsTnII as a spontaneous mutant. Apparently, membranes of DmTn11 lack M(IP)2C, whereas membranes of HsTnII have increased M(IP)2C levels. In addition, DmTn11 and HsTnII are characterized by increased and reduced oxidative stress resistance/chronological life‐span (CL), respectively. A putative involvement of M(IP)2C in oxidative stress and CL in yeast is discussed.