ESCRTs function directly on the lysosome membrane to downregulate ubiquitinated lysosomal membrane proteins

• Published in: eLife Vol. 6
• Main Authors: Zhu, Lu, Jorgensen, Jeff R, Li, Ming, Chuang, Ya-Shan, Emr, Scott D
• Format: Journal Article
• Language: English
• Published: England eLife Sciences Publications Ltd 29.06.2017; eLife Sciences Publications, Ltd
• Subjects: cargo sorting; Cell Biology; Down-Regulation; Endosomal Sorting Complexes Required for Transport - genetics; Endosomal Sorting Complexes Required for Transport - metabolism; ESCRT; Genetic screening; Genetic Testing; Genomes; Homeostasis; lysosomal membrane protein; Lysosomal Membrane Proteins - metabolism; lysosome; Lysosomes - metabolism; membrane protein regulation; Membrane proteins; Microscopy; Molecular biology; protein degradation; Proteins; Rapamycin; Saccharomyces cerevisiae - genetics; Saccharomyces cerevisiae - metabolism; Ubiquitin; Ubiquitin-protein ligase; Ubiquitination; Yeast; cell biology; ESCRT; cargo sorting; lysosomal membrane protein; membrane protein regulation; lysosome; protein degradation; S. cerevisiae
• ISSN: 2050-084X; 2050-084X
• DOI: 10.7554/elife.26403

The lysosome plays an important role in maintaining cellular nutrient homeostasis. Regulation of nutrient storage can occur by the ubiquitination of certain transporters that are then sorted into the lysosome lumen for degradation. To better understand the underlying mechanism of this process, we performed genetic screens to identify components of the sorting machinery required for vacuole membrane protein degradation. These screens uncovered genes that encode a ubiquitin ligase complex, components of the PtdIns 3-kinase complex, and the ESCRT machinery. We developed a novel ubiquitination system, amycin nduced radation (RapiDeg), to test the sorting defects caused by these mutants. These tests revealed that ubiquitinated vacuole membrane proteins recruit ESCRTs to the vacuole surface, where they mediate cargo sorting and direct cargo delivery into the vacuole lumen. Our findings demonstrate that the ESCRTs can function at both the late endosome and the vacuole membrane to mediate cargo sorting and intra-luminal vesicle formation.