Function of the SNARE Ykt6 on autophagosomes requires the Dsl1 complex and the Atg1 kinase complex

Autor(en): Gao, Jieqiong
Kurre, Rainer 
Rose, Jaqueline
Walter, Stefan
Froehlich, Florian 
Piehler, Jacob 
Reggiori, Fulvio
Ungermann, Christian 
Stichwörter: autophagy; Biochemistry & Molecular Biology; Cell Biology; COPII vesicles; Dsl1 complex; EARLY STEPS; EARLY-STAGE; ENDOPLASMIC RETICULUM RETRIEVAL; GOLGI; PROTEIN; R-SNARE; SACCHAROMYCES-CEREVISIAE; SNARE; TETHERING COMPLEX; VESICLE FORMATION; YEAST; Ykt6
Erscheinungsdatum: 2020
Herausgeber: WILEY
Journal: EMBO REPORTS
Volumen: 21
Ausgabe: 12
Zusammenfassung: 
The mechanism and regulation of fusion between autophagosomes and lysosomes/vacuoles are still only partially understood in both yeast and mammals. In yeast, this fusion step requires SNARE proteins, the homotypic vacuole fusion and protein sorting (HOPS) tethering complex, the RAB7 GTPase Ypt7, and its guanine nucleotide exchange factor (GEF) Mon1-Ccz1. We and others recently identified Ykt6 as the autophagosomal SNARE protein. However, it has not been resolved when and how lipid-anchored Ykt6 is recruited onto autophagosomes. Here, we show that Ykt6 is recruited at an early stage of the formation of these carriers through a mechanism that depends on endoplasmic reticulum (ER)-resident Dsl1 complex and COPII-coated vesicles. Importantly, Ykt6 activity on autophagosomes is regulated by the Atg1 kinase complex, which inhibits Ykt6 through direct phosphorylation. Thus, our findings indicate that the Ykt6 pool on autophagosomal membranes is kept inactive by Atg1 phosphorylation, and once an autophagosome is ready to fuse with vacuole, Ykt6 dephosphorylation allows its engagement in the fusion event.
ISSN: 1469221X
DOI: 10.15252/embr.202050733

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