BPS2026 – Temperature at which yeast vacuole membranes undergo liquid-liquid phase separation as a function of time in the stationary stage (Tmix vs time)

Under nutrient deprivation, yeast transitions from the logarithmic to the stationary stage. In the stationary stage, the membrane of the vacuole, a lysosomal organelle, phase separates into micron-scale, liquid domains. Previous researchers have found: (1) most transmembrane proteins preferentially partition to the membrane phase that is less ordered and has less cholesterol, and (2) as time (and nutrient deprivation) progresses, the area fraction of this less-ordered membrane phase decreases (Toulmay and Prinz JCB 2013). Here, we investigate whether the time of nutrient deprivation also influences the transition temperature, Tmix. In stationary stage, yeast regulate their vacuole membranes to maintain Tmix above the growth temperature (Leveille et al. PNAS 2022). However, it is unknown whether Tmix changes throughout the stationary stage. We will compare our results with model vesicles, in which Tmix increases and then decreases with increasing area fraction along a tie-line.