A metabolically controlled contact site between lipid droplets and vacuoles

SUMMARY The lipid d roplet (LD) o rganization proteins Ldo16 and Ldo45 affect multiple aspects of LD biology in yeast. They are linked to the LD biogenesis machinery seipin, and their loss causes defects in LD positioning, protein targeting, and breakdown. However, their molecular roles remained enigmatic. Here we report that Ldo16/45 form a tether-complex with Vac8 for creation of v a c uole lip id droplet (vCLIP) contact sites, which can form in the absence of seipin. The phosphatidylinositol transfer protein Pdr16 is a further vCLIP-resident recruited by Ldo45. While only an LD-subpopulation is engaged in vCLIPs at glucose-replete conditions, nutrient stress results in vCLIP expansion, and vCLIP defects impair lipophagy upon prolonged starvation. In summary, Ldo16/45 are multifunctional proteins that orchestrate formation of a metabolically-regulated contact site. Our studies suggest an unexpected link between LD biogenesis and breakdown, and open the door to a deeper understanding of how lipid homeostasis is maintained during metabolic challenges.