The phosphatase Glc7 controls eisosomal response to starvation via posttranslational modification of Pil1

Abstract

The yeast plasma membrane (PM) is organised into specific subdomains that regulate surface membrane proteins. Surface transporters actively uptake nutrients in particular regions of the PM where they are also susceptible to substrate induced endocytosis. However, transporters also diffuse into distinct subdomains termed eisosomes, where they are protected from endocytosis. Although most nutrient transporter populations are downregulated in the vacuole following glucose starvation, a small pool is retained in eisosomes to provide efficient recovery from starvation. We find the core eisosome subunit Pil1, a Bin, Amphiphysin and Rvs (BAR) domain protein required for eisosome biogenesis, is phosphorylated primarily by the kinase Pkh2. In response to acute glucose starvation, Pil1 is rapidly dephosphorylated. Enzyme localisation and activity screens implicate the phosphatase Glc7 is the primary enzyme responsible for Pil1 dephosphorylation. Both depletion of GLC7 and phospho-ablative or phospho-mimetic mutations of Pil1 correlate with Pil1 phosphorylation status, failure to properly retain transporters in eisosomes, and results in defective starvation recovery. We propose precise posttranslational control of Pil1 modulates nutrient transporter retention within eisosomes depending on extracellular nutrient levels, to maximise recovery following starvation.