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Title: ATG14 promotes membrane tethering and fusion of autophagosomes to endolysosomes

Authors:
; ; ; ; ; ; ; ; ; ; ; ;  [1];  [2];  [2]
  1. Stanford
  2. (
Publication Date:
Research Org.:
Argonne National Lab. (ANL), Argonne, IL (United States). Advanced Photon Source (APS)
Sponsoring Org.:
NIHOTHER
OSTI Identifier:
1225078
Resource Type:
Journal Article
Resource Relation:
Journal Name: Nature (London); Journal Volume: 520; Journal Issue: 04, 2015
Country of Publication:
United States
Language:
ENGLISH

Citation Formats

Diao, Jiajie, Liu, Rong, Rong, Yueguang, Zhao, Minglei, Zhang, Jing, Lai, Ying, Zhou, Qiangjun, Wilz, Livia M., Li, Jianxu, Vivona, Sandro, Pfuetzner, Richard A., Brunger, Axel T., Zhong, Qing, UTSMC), and UCB). ATG14 promotes membrane tethering and fusion of autophagosomes to endolysosomes. United States: N. p., 2016. Web. doi:10.1038/nature14147.
Diao, Jiajie, Liu, Rong, Rong, Yueguang, Zhao, Minglei, Zhang, Jing, Lai, Ying, Zhou, Qiangjun, Wilz, Livia M., Li, Jianxu, Vivona, Sandro, Pfuetzner, Richard A., Brunger, Axel T., Zhong, Qing, UTSMC), & UCB). ATG14 promotes membrane tethering and fusion of autophagosomes to endolysosomes. United States. doi:10.1038/nature14147.
Diao, Jiajie, Liu, Rong, Rong, Yueguang, Zhao, Minglei, Zhang, Jing, Lai, Ying, Zhou, Qiangjun, Wilz, Livia M., Li, Jianxu, Vivona, Sandro, Pfuetzner, Richard A., Brunger, Axel T., Zhong, Qing, UTSMC), and UCB). 2016. "ATG14 promotes membrane tethering and fusion of autophagosomes to endolysosomes". United States. doi:10.1038/nature14147.
@article{osti_1225078,
title = {ATG14 promotes membrane tethering and fusion of autophagosomes to endolysosomes},
author = {Diao, Jiajie and Liu, Rong and Rong, Yueguang and Zhao, Minglei and Zhang, Jing and Lai, Ying and Zhou, Qiangjun and Wilz, Livia M. and Li, Jianxu and Vivona, Sandro and Pfuetzner, Richard A. and Brunger, Axel T. and Zhong, Qing and UTSMC) and UCB)},
abstractNote = {},
doi = {10.1038/nature14147},
journal = {Nature (London)},
number = 04, 2015,
volume = 520,
place = {United States},
year = 2016,
month = 7
}
  • The multimeric membrane-tethering complexes TRAPPI and TRAPPII share seven subunits, of which four (Bet3p, Bet5p, Trs23p, and Trs31p) are minimally needed to activate the Rab GTPase Ypt1p in an event preceding membrane fusion. Here, we present the structure of a heteropentameric TRAPPI assembly complexed with Ypt1p. We propose that TRAPPI facilitates nucleotide exchange primarily by stabilizing the nucleotide-binding pocket of Ypt1p in an open, solvent-accessible form. Bet3p, Bet5p, and Trs23p interact directly with Ypt1p to stabilize this form, while the C terminus of Bet3p invades the pocket to participate in its remodeling. The Trs31p subunit does not interact directly withmore » the GTPase but allosterically regulates the TRAPPI interface with Ypt1p. Our findings imply that TRAPPII activates Ypt1p by an identical mechanism. This view of a multimeric membrane-tethering assembly complexed with a Rab provides a framework for understanding events preceding membrane fusion at the molecular level.« less
  • Biogenesis of the ribbon-like membrane network of the mammalian Golgi requires membrane tethering by the conserved GRASP domain in GRASP65 and GRASP55, yet the tethering mechanism is not fully understood. Here, we report the crystal structure of the GRASP55 GRASP domain, which revealed an unusual arrangement of two tandem PDZ folds that more closely resemble prokaryotic PDZ domains. Biochemical and functional data indicated that the interaction between the ligand-binding pocket of PDZ1 and an internal ligand on PDZ2 mediates the GRASP self-interaction, and structural analyses suggest that this occurs via a unique mode of internal PDZ ligand recognition. Our datamore » uncover the structural basis for ligand specificity and provide insight into the mechanism of GRASP-dependent membrane tethering of analogous Golgi cisternae.« less
  • Biogenesis of the ribbon-like membrane network of the mammalian Golgi requires membrane tethering by the conserved GRASP domain in GRASP65 and GRASP55, yet the tethering mechanism is not fully understood. Here, we report the crystal structure of the GRASP55 GRASP domain, which revealed an unusual arrangement of two tandem PDZ folds that more closely resemble prokaryotic PDZ domains. Biochemical and functional data indicated that the interaction between the ligand-binding pocket of PDZ1 and an internal ligand on PDZ2 mediates the GRASP self-interaction, and structural analyses suggest that this occurs via a unique mode of internal PDZ ligand recognition. Our datamore » uncover the structural basis for ligand specificity and provide insight into the mechanism of GRASP-dependent membrane tethering of analogous Golgi cisternae.« less
  • ATG14 binding to BECN/Beclin homologs is essential for autophagy, a critical catabolic homeostasis pathway. Here, we show that the α-helical, coiled-coil domain (CCD) of BECN2, a recently identified mammalian BECN1 paralog, forms an antiparallel, curved homodimer with seven pairs of nonideal packing interactions, while the BECN2 CCD and ATG14 CCD form a parallel, curved heterodimer stabilized by multiple, conserved polar interactions. Compared to BECN1, the BECN2 CCD forms a weaker homodimer, but binds more tightly to the ATG14 CCD. Mutation of nonideal BECN2 interface residues to more ideal pairs improves homodimer self-association and thermal stability. Unlike BECN1, all BECN2 CCDmore » mutants bind ATG14, although more weakly than wild type. Thus, polar BECN2 CCD interface residues result in a metastable homodimer, facilitating dissociation, but enable better interactions with polar ATG14 residues stabilizing the BECN2:ATG14 heterodimer. These structure-based mechanistic differences in BECN1 and BECN2 homodimerization and heterodimerization likely dictate competitive ATG14 recruitment.« less
  • Highlights: ► CCCP-induced LC3 lipidation can be independent of initiation/nucleation molecules. ► Atg9-mediated trafficking is critically required for CCCP-induced LC3 lipidation. ► CCCP-induced mitophagy may thus be more dependent on Atg9-positive vesicles. -- Abstract: Treatment of cells with carbonyl cyanide m-chlorophenylhydrazone (CCCP), a mitochondrial proton gradient uncoupler, can result in mitochondrial damage and autophagy activation, which in turn eliminates the injured mitochondria in a Parkin-dependent way. How CCCP mobilizes the autophagy machinery is not fully understood. By analyzing a key autophagy step, LC3 lipidation, we examined the roles of two kinase complexes typically involved in the initiation and nucleation phasesmore » of autophagy, namely the ULK kinase complex (UKC) and the Beclin 1/Atg14 complex. We found that CCCP-induced LC3 lipidation could be independent of Beclin 1 and Atg14. In addition, deletion or knockdown of the UKC component FIP200 or Atg13 only led to a partial reduction in LC3 lipidation, indicating that UKC could be also dispensable for this step during CCCP treatment. In contrast, Atg9, which is important for transporting vesicles to early autophagosomal structure, was required for CCCP-induced LC3 lipidation. Taken together, these data suggest that CCCP-induced autophagy and mitophagy depends more critically on Atg9 vesicles than on UKC and Beclin 1/Atg14 complex.« less