Insights on autophagosome-lysosome tethering from structural and biochemical characterization of human autophagy factor EPG5.

Abstract

Pivotal to the maintenance of cellular homeostasis, macroautophagy (hereafter autophagy) is an evolutionarily conserved degradation system that involves sequestration of cytoplasmic material into the double-membrane autophagosome and targeting of this transport vesicle to the lysosome/late endosome for degradation. EPG5 is a large-sized metazoan protein proposed to serve as a tethering factor to enforce autophagosome-lysosome/late endosome fusion specificity, and its deficiency causes a severe multisystem disorder known as Vici syndrome. Here, we show that human EPG5 (hEPG5) adopts an extended "shepherd's staff" architecture. We find that hEPG5 binds preferentially to members of the GABARAP subfamily of human ATG8 proteins critical to autophagosome-lysosome fusion. The hEPG5-GABARAPs interaction, which is mediated by tandem LIR motifs that exhibit differential affinities, is required for hEPG5 recruitment to mitochondria during PINK1/Parkin-dependent mitophagy. Lastly, we find that the Vici syndrome mutation Gln336Arg does not affect the hEPG5's overall stability nor its ability to engage in interaction with the GABARAPs. Collectively, results from our studies reveal new insights into how hEPG5 recognizes mature autophagosome and establish a platform for examining the molecular effects of Vici syndrome disease mutations on hEPG5.

• Authors: Sung-Eun Nam, Yiu Wing Sunny Cheung, Thanh Ngoc Nguyen, Michael Gong, Samuel Chan, Michael Lazarou, Calvin K Yip
• Journal: Communications biology (Commun Biol) Vol. 4 Issue 1 Pg. 291 (03 05 2021) ISSN: 2399-3642 [Electronic] England
• PMID: 33674710 (Publication Type: Journal Article, Research Support, N.I.H., Extramural, Research Support, Non-U.S. Gov't, Research Support, U.S. Gov't, Non-P.H.S.)

Chemical References

• Adaptor Proteins, Signal Transducing
• Apoptosis Regulatory Proteins
• Autophagy-Related Protein 8 Family
• Autophagy-Related Proteins
• EPG5 protein, human
• GABARAP protein, human
• GABARAPL1 protein, human
• GABARAPL2 protein, human
• Microtubule-Associated Proteins
• Vesicular Transport Proteins

Topics

• Adaptor Proteins, Signal Transducing (metabolism)
• Agenesis of Corpus Callosum (genetics, metabolism)
• Animals
• Apoptosis Regulatory Proteins (metabolism)
• Autophagosomes (metabolism)
• Autophagy-Related Protein 8 Family (metabolism)
• Autophagy-Related Proteins (genetics, metabolism)
• Cataract (genetics, metabolism)
• Genetic Predisposition to Disease
• HeLa Cells
• Humans
• Lysosomes (metabolism)
• Microtubule-Associated Proteins (metabolism)
• Mitochondria (metabolism)
• Mitophagy
• Mutation
• Protein Binding
• Protein Conformation
• Protein Interaction Domains and Motifs
• Protein Stability
• Protein Transport
• Proteolysis
• Sf9 Cells
• Structure-Activity Relationship
• Vesicular Transport Proteins (genetics, metabolism)