a Institute of Biochemistry and Molecular Biology, ZBMZ, Faculty of Medicine , University of Freiburg , Freiburg , Germany.
b Max F. Perutz Laboratories, Vienna Biocenter , University of Vienna , Vienna , Austria.
Cell Cycle. 2019 Mar-Apr;18(6-7):639-651. doi: 10.1080/15384101.2019.1580488. Epub 2019 Mar 17.
Autophagy is a degradative pathway in which cytosolic material is enwrapped within double membrane vesicles, so-called autophagosomes, and delivered to lytic organelles. SNARE (Soluble N-ethylmaleimide sensitive factor attachment protein receptor) proteins are key to drive membrane fusion of the autophagosome and the lytic organelles, called lysosomes in higher eukaryotes or vacuoles in plants and yeast. Therefore, the identification of functional SNARE complexes is central for understanding fusion processes and their regulation. The SNARE proteins Syntaxin 17, SNAP29 and Vamp7/VAMP8 are responsible for the fusion of autophagosomes with lysosomes in higher eukaryotes. Recent studies reported that the R-SNARE Ykt6 is an additional SNARE protein involved in autophagosome-lytic organelle fusion in yeast, Drosophila, and mammals. These current findings point to an evolutionarily conserved role of Ykt6 in autophagosome-related fusion events. Here, we briefly summarize the principal mechanisms of autophagosome-lytic organelle fusion, with a special focus on Ykt6 to highlight some intrinsic features of this unusual SNARE protein.
自噬是一种降解途径，其中细胞质物质被双层膜囊泡（即自噬体）包裹，并递送至溶酶体等裂解细胞器。SNARE（可溶性 N-乙基马来酰亚胺敏感因子附着蛋白受体）蛋白是驱动自噬体与溶酶体（高等真核生物中称为溶酶体或植物和酵母中的液泡）融合的关键。因此，鉴定功能性 SNARE 复合物对于理解融合过程及其调控至关重要。SNARE 蛋白 Syntaxin 17、SNAP29 和 Vamp7/VAMP8 负责高等真核生物中自噬体与溶酶体的融合。最近的研究报道，R-SNARE Ykt6 是酵母、果蝇和哺乳动物中参与自噬体-溶酶体融合的另一种 SNARE 蛋白。这些新发现表明 Ykt6 在与自噬体相关的融合事件中具有保守的作用。本文简要总结了自噬体-溶酶体融合的主要机制，特别关注 Ykt6，以突出这种不寻常的 SNARE 蛋白的一些内在特征。
