TY - JOUR
T1 - ATG14 promotes membrane tethering and fusion of autophagosomes to endolysosomes
AU - Diao, Jiajie
AU - Liu, Rong
AU - Rong, Yueguang
AU - Zhao, Minglei
AU - Zhang, Jing
AU - Lai, Ying
AU - Zhou, Qiangjun
AU - Wilz, Livia M.
AU - Li, Jianxu
AU - Vivona, Sandro
AU - Pfuetzner, Richard A.
AU - Brunger, Axel T.
AU - Zhong, Qing
N1 - Funding Information:
Acknowledgements We thank Q. Sun, W. Fan, M. Padolina and R. Bellerose for technical assistance, Y. Cheng and S. Wu for help in the cryo-electron microscopy experiments, A. Liang at OCS Microscopy Core of New York University Langone Medical Center for electron microscope analysis, the Northeastern Collaborative Access Team (supported by National Institutes of Health (NIH) P41 GM103403) at the Advanced Photon Source for X-ray data collection, and B. Levine and R. Sumpter for reading the manuscript. The work was supported by grants to Q.Z. from the Welch Foundation (I-1864), the Cancer Prevention & Research Institute of Texas (RP140320), an AmericanCancer Society ResearchScholarGrant(RSG-11-274-01-CCG) andNIH R01 (CA133228), and NIH R01 (R37-MH63105) to A.T.B. The work was partly supported by China Scholarship Council to R.L. This work was also supported by the National Cancer Institute of the NIH under award number 5P30CA142543.
Publisher Copyright:
©2015 Macmillan Publishers Limited. All rights reserved.
PY - 2015/4/23
Y1 - 2015/4/23
N2 - Autophagy, an important catabolic pathway implicated in a broad spectrum of human diseases, begins by forming double membrane autophagosomes that engulf cytosolic cargo and ends by fusing autophagosomes with lysosomes for degradation. Membrane fusion activity is required for early biogenesis of autophagosomes and late degradation in lysosomes. However, the key regulatory mechanisms of autophagic membrane tethering and fusion remain largely unknown. Here we report that ATG14 (also known as beclin-1-associated autophagy-related key regulator (Barkor) or ATG14L), an essential autophagy-specific regulator of the class III phosphatidylinositol 3-kinase complex, promotes membrane tethering of protein-free liposomes, and enhances hemifusion and full fusion of proteoliposomes reconstituted with the target (t)-SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) syntaxin 17 (STX17) and SNAP29, and the vesicle (v)-SNARE VAMP8 (vesicle-associated membrane protein 8). ATG14 binds to the SNARE core domain of STX17 through its coiled-coil domain, and stabilizes the STX17-SNAP29 binary t-SNARE complex on autophagosomes. The STX17 binding, membrane tethering and fusion-enhancing activities of ATG14 require its homo-oligomerization by cysteine repeats. In ATG14 homo-oligomerization-defective cells, autophagosomes still efficiently form but their fusion with endolysosomes is blocked. Recombinant ATG14 homo-oligomerization mutants also completely lose their ability to promote membrane tethering and to enhance SNARE-mediated fusion in vitro. Taken together, our data suggest an autophagy-specific membrane fusion mechanism in which oligomeric ATG14 directly binds to STX17-SNAP29 binary t-SNARE complex on autophagosomes and primes it for VAMP8 interaction to promote autophagosome-endolysosome fusion.
AB - Autophagy, an important catabolic pathway implicated in a broad spectrum of human diseases, begins by forming double membrane autophagosomes that engulf cytosolic cargo and ends by fusing autophagosomes with lysosomes for degradation. Membrane fusion activity is required for early biogenesis of autophagosomes and late degradation in lysosomes. However, the key regulatory mechanisms of autophagic membrane tethering and fusion remain largely unknown. Here we report that ATG14 (also known as beclin-1-associated autophagy-related key regulator (Barkor) or ATG14L), an essential autophagy-specific regulator of the class III phosphatidylinositol 3-kinase complex, promotes membrane tethering of protein-free liposomes, and enhances hemifusion and full fusion of proteoliposomes reconstituted with the target (t)-SNAREs (soluble N-ethylmaleimide-sensitive factor attachment protein receptors) syntaxin 17 (STX17) and SNAP29, and the vesicle (v)-SNARE VAMP8 (vesicle-associated membrane protein 8). ATG14 binds to the SNARE core domain of STX17 through its coiled-coil domain, and stabilizes the STX17-SNAP29 binary t-SNARE complex on autophagosomes. The STX17 binding, membrane tethering and fusion-enhancing activities of ATG14 require its homo-oligomerization by cysteine repeats. In ATG14 homo-oligomerization-defective cells, autophagosomes still efficiently form but their fusion with endolysosomes is blocked. Recombinant ATG14 homo-oligomerization mutants also completely lose their ability to promote membrane tethering and to enhance SNARE-mediated fusion in vitro. Taken together, our data suggest an autophagy-specific membrane fusion mechanism in which oligomeric ATG14 directly binds to STX17-SNAP29 binary t-SNARE complex on autophagosomes and primes it for VAMP8 interaction to promote autophagosome-endolysosome fusion.
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U2 - 10.1038/nature14147
DO - 10.1038/nature14147
M3 - Article
C2 - 25686604
AN - SCOPUS:84928550400
SN - 0028-0836
VL - 520
SP - 563
EP - 566
JO - Nature
JF - Nature
IS - 7548
ER -