Starvation-Dependent Regulation of Golgi Quality Control Links the TOR Signaling and Vacuolar Protein Sorting Pathways.

Abstract

Upon amino acid (AA) starvation and TOR inactivation, plasma-membrane-localized permeases rapidly undergo ubiquitination and internalization via the vacuolar protein sorting/multivesicular body (VPS-MVB) pathway and are degraded in the yeast vacuole. We now show that specific Golgi proteins are also directed to the vacuole under these conditions as part of a Golgi quality-control (GQC) process. The degradation of GQC substrates is dependent upon ubiquitination by the defective-for-SREBP-cleavage (DSC) complex, which was identified via genetic screening and includes the Tul1 E3 ligase. Using a model GQC substrate, GFP-tagged Yif1, we show that vacuolar targeting necessitates upregulation of the VPS pathway via proteasome-mediated degradation of the initial endosomal sorting complex required for transport, ESCRT-0, but not downstream ESCRT components. Thus, early cellular responses to starvation include the targeting of specific Golgi proteins for degradation, a phenomenon reminiscent of the inactivation of BTN1, the yeast Batten disease gene ortholog.

• Authors: Niv Dobzinski, Silvia G Chuartzman, Rachel Kama, Maya Schuldiner, Jeffrey E Gerst
• Journal: Cell reports (Cell Rep) Vol. 12 Issue 11 Pg. 1876-86 (Sep 22 2015) ISSN: 2211-1247 [Electronic] United States
• PMID: 26344761 (Publication Type: Journal Article, Research Support, Non-U.S. Gov't)
• Copyright: Copyright © 2015 The Authors. Published by Elsevier Inc. All rights reserved.

Chemical References

• Adaptor Proteins, Vesicular Transport
• Endosomal Sorting Complexes Required for Transport
• Saccharomyces cerevisiae Proteins
• YIF1 protein, S cerevisiae
• Ubc4 protein, S cerevisiae
• Ubiquitin-Conjugating Enzymes
• TOR Serine-Threonine Kinases

Topics

• Adaptor Proteins, Vesicular Transport (metabolism)
• Endosomal Sorting Complexes Required for Transport (genetics, metabolism)
• Golgi Apparatus (enzymology, metabolism)
• Protein Transport
• Quality Control
• Saccharomyces cerevisiae (genetics, metabolism)
• Saccharomyces cerevisiae Proteins (metabolism)
• Signal Transduction
• TOR Serine-Threonine Kinases (metabolism)
• Ubiquitin-Conjugating Enzymes (metabolism)