Modification of sterol composition in yeast cell membrane from ergosterol to cholesterol and its effect on Ste2 signaling

In human cell membrane, cholesterol is required for functionalization of membrane proteins such as some human G‐protein‐coupled receptors (GPCRs). However, in yeast, ergosterol is the main sterol of cell membrane. Therefore, we investigated the effect of altered sterol composition in yeast cell membrane from ergosterol to cholesterol on GPCR signaling. The cholesterol‐producing yeast instead of ergosterol was constructed by disrupting the ergosterol‐related genes and introducing the genes for cholesterol synthesis. The GC‐MS analysis of the sterol composition in the constructed yeast indicated that cholesterol was successfully produced as one of the major sterols instead of ergosterol. The activity of yeast pheromone GPCR Ste2 in the cholesterol‐producing yeast was evaluated by measuring the activation of the FUS1 promoter. Ste2 signaling was detected even in the cholesterol‐producing yeast, but the maximum signal intensity was weaker than that in wild type yeast. The result suggests that sterol composition is important for the activity of GPCRs. Therefore, the optimization of the sterol composition would extend the range of application of yeast into the analysis of heterogenous GPCRs such as human GPCRs.