Bet3 participates in autophagy through GTPase Ypt1 in Saccharomyces cerevisiae
Bet3 participates in autophagy through GTPase Ypt1 in Saccharomyces cerevisiae
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DOI：
10.1002/cbin.10416
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发表时间：
2015-04
影响因子：
3.9
通讯作者：
Shenshen Zou;Yutao Liu;Caiyun Zhang;Sidney Yu;Yongheng Liang
中科院分区：
文献类型：
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作者：
Shenshen Zou;Yutao Liu;Caiyun Zhang;Sidney Yu;Yongheng Liang
三个TRAPP（转运蛋白颗粒）复合物已被确定在酿酒酵母。GTP酶Ypt 1和Ypt 31/32分别抑制TRAPP III特异性亚基（Trs 85）和TRAPP II特异性亚基（Trs 130和Trs 120）突变体中的自噬缺陷。然而，常见的TRAPP亚基（也形成TRAPPI复合物）在自噬中的作用及其与自噬中Rab GTP酶的关系仍不清楚。由于Bet 3（一种常见的TRAPP亚基）不能与Trs 85或Trs 130一起突变，我们研究了bet 3 ts细胞中饥饿诱导的自噬和细胞质-液泡靶向（Cvt）途径。结果表明，GFP-Atg 8分散在细胞质中，Ape 1在bet 3 ts细胞中以液泡膜上的独特点的形式积累。进一步的分析表明，Ape 1成熟和GFP-Atg 8加工在这些细胞中是有缺陷的。然而，PrApe 1（Ape 1的前体形式）和GFP-Atg 8在饥饿条件下的bet 3 ts细胞中是蛋白酶可接近的，这表明Bet 3在自噬体关闭之前起作用。此外，活性Ypt 1，而不是Ypt 31，部分挽救了bet 3 ts细胞的自噬缺陷。我们的结论是，Bet 3参与自噬，并提出它参与自噬通过TRAPP复合物主要是通过Ypt 1在酵母中。
Three TRAPP (transport protein particle) complexes have been identified in Saccharomyces cerevisiae. GTPases Ypt1 and Ypt31/32 suppress autophagic defects in the mutants of TRAPPIII‐specific subunit (Trs85) and TRAPPII‐specific subunits (Trs130 and Trs120), respectively. However, the roles of the common TRAPP subunits (which also form the TRAPPI complex) in autophagy and their relationship to Rab GTPases in autophagy remain unclear. As Bet3 (a common TRAPP subunit) cannot be mutated together with either Trs85 or Trs130, we examined starvation‐induced autophagy and the cytoplasm‐to‐vacuole targeting (Cvt) pathway in bet3ts cells. The results demonstrated that GFP‐Atg8 was dispersed in the cytoplasm and Ape1 accumulated as a unique dot on the vacuolar membrane in bet3ts cells. Further analysis revealed that Ape1 maturation and GFP‐Atg8 processing are defective in these cells. However, prApe1 (precursor form of Ape1) and GFP‐Atg8 are protease‐accessible in bet3ts cells under starvation, which indicates that Bet3 functions before autophagosome closure. Furthermore, active Ypt1, but not Ypt31, partly rescued the autophagic defects of bet3ts cells. We conclude that Bet3 is involved in autophagy and propose that it participates in autophagy through TRAPP complexes mostly via Ypt1 in yeast.