ИСТИНА

Ysp2p belongs to the evolutionarily diverse family of endoplasmic reticulum (ER) membrane proteins with StART-like lipid transfer domains called Lams. Ysp2p and its homologs Ysp1p, Sip3p and Lam4p are localized at ER-plasma membrane (PM) contact sites distinct from those occupied by the known ER-PM tethers. There is some evidence that Ysp2p, Ysp1p and Sip3p transport ergosterol from PM to ER. Here we showed that Ysp2p is necessary for the adaptation of S. cerevisiae cells to the various stresses. The deletion of Δysp2 leads to increased sensitivity to hyperosmotic stress, heat shock, drying and freezing. Δysp2 is more sensitive to the antimycotic miconazole and has no pronounced sensitivity to other antimycotics, such as clotrimazole, fluconazole or ketoconazole. Overexpression of YSP2, on the contrary, leads to an increase in the cell resistance to hyperosmotic stress and miconazole. We studied the combined effect for ergosterol biosynthesis genes deletion (Δerg2-6) with the deletion of Δysp2 or its overexpression and found genetic interaction between them in terms of hyperosmotic stress and amiodarone resistance (Ysp2p was initially selected as providing resistance to ion channels blocker - drug amiodarone). Since PM distribution of ergosterol is uneven, we investigated the possibility of Ysp2p colocalization with the lipid rafts proteins Pma1p, Can1p and Pdr5p and did not find any. This work was supported by Russian Science Foundation (grant 14-24-00107).