TY - JOUR
T1 - Autophagosomal YKT6 is required for fusion with lysosomes independently of syntaxin 17
AU - Matsui, Takahide
AU - Jiang, Peidu
AU - Nakano, Saori
AU - Sakamaki, Yuriko
AU - Yamamoto, Hayashi
AU - Mizushima, Noboru
N1 - Funding Information:
This work was supported by Japan Society for the Promotion of Science Grant-in-Aid for Scientific Research on Innovative Areas (grant 25111005) and Japan Science and Technology Agency Exploratory Research for Advanced Technology (ERATO; grant JPMJER1702) to N. Mizushima. The authors declare no competing financial interests.
PY - 2018/8/1
Y1 - 2018/8/1
N2 - Macroautophagy is an evolutionarily conserved catabolic mechanism that delivers intracellular constituents to lysosomes using autophagosomes. To achieve degradation, lysosomes must fuse with closed autophagosomes. We previously reported that the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein syntaxin (STX) 17 translocates to autophagosomes to mediate fusion with lysosomes. In this study, we report an additional mechanism. We found that autophagosome-lysosome fusion is retained to some extent even in STX17 knockout (KO) HeLa cells. By screening other human SNAREs, we identified YKT6 as a novel autophagosomal SNARE protein. Depletion of YKT6 inhibited autophagosome-lysosome fusion partially in wild-type and completely in STX17 KO cells, suggesting that YKT6 and STX17 are independently required for fusion. YKT6 formed a SNARE complex with SNAP29 and lysosomal STX7, both of which are required for autophagosomal fusion. Recruitment of YKT6 to autophagosomes depends on its N-terminal longin domain but not on the C-terminal palmitoylation and farnesylation that are essential for its Golgi localization. These findings suggest that two independent SNARE complexes mediate autophagosome-lysosome fusion.
AB - Macroautophagy is an evolutionarily conserved catabolic mechanism that delivers intracellular constituents to lysosomes using autophagosomes. To achieve degradation, lysosomes must fuse with closed autophagosomes. We previously reported that the soluble N-ethylmaleimide-sensitive factor attachment protein receptor (SNARE) protein syntaxin (STX) 17 translocates to autophagosomes to mediate fusion with lysosomes. In this study, we report an additional mechanism. We found that autophagosome-lysosome fusion is retained to some extent even in STX17 knockout (KO) HeLa cells. By screening other human SNAREs, we identified YKT6 as a novel autophagosomal SNARE protein. Depletion of YKT6 inhibited autophagosome-lysosome fusion partially in wild-type and completely in STX17 KO cells, suggesting that YKT6 and STX17 are independently required for fusion. YKT6 formed a SNARE complex with SNAP29 and lysosomal STX7, both of which are required for autophagosomal fusion. Recruitment of YKT6 to autophagosomes depends on its N-terminal longin domain but not on the C-terminal palmitoylation and farnesylation that are essential for its Golgi localization. These findings suggest that two independent SNARE complexes mediate autophagosome-lysosome fusion.
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U2 - 10.1083/jcb.201712058
DO - 10.1083/jcb.201712058
M3 - Article
C2 - 29789439
AN - SCOPUS:85054068934
VL - 217
SP - 2633
EP - 2645
JO - Journal of Cell Biology
JF - Journal of Cell Biology
SN - 0021-9525
IS - 8
ER -