The Yeast ER-Intramembrane Protease Ypf1 Refines Nutrient Sensing by Regulating Transporter Abundance

• Yeast intramembrane protease Ypf1 controls abundance of polytopic membrane proteins
• Ypf1 functionally interacts with the ERAD factors Dfm1 and Doa10
• ERAD regulatory (ERAD-R) controls abundance of high-affinity zinc transporters
• ERAD-R is essential to prepare yeast for starvation and subsequent recovery

SummaryProteolysis by aspartyl intramembrane proteases such as presenilin and signal peptide peptidase (SPP) underlies many cellular processes in health and disease. Saccharomyces cerevisiae encodes a homolog that we named yeast presenilin fold 1 (Ypf1), which we verify to be an SPP-type protease that localizes to the endoplasmic reticulum (ER). Our work shows that Ypf1 functionally interacts with the ER-associated degradation (ERAD) factors Dfm1 and Doa10 to regulate the abundance of nutrient transporters by degradation. We demonstrate how this noncanonical branch of the ERAD pathway, which we termed “ERAD regulatory” (ERAD-R), responds to ligand-mediated sensing as a trigger. More generally, we show that Ypf1-mediated posttranslational regulation of plasma membrane transporters is indispensible for early sensing and adaptation to nutrient depletion. The combination of systematic analysis alongside mechanistic details uncovers a broad role of intramembrane proteolysis in regulating secretome dynamics.

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