The membrane dynamics of pexophagy are influenced by Sar1p in Pichia pastoris.
The membrane dynamics of pexophagy are influenced by Sar1p in Pichia pastoris.
复制标题
pexophagy 的膜动力学受毕赤酵母中 Sar1p 的影响。
DOI：
10.1091/mbc.e07-09-0868
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发表时间：
2008
影响因子：
3.3
通讯作者：
DunnJr,WilliamA
中科院分区：
文献类型：
--
作者：
Schroder,LauraA;Ortiz,MichaelV;DunnJr,WilliamA
几种Sec蛋白，包括用于Sar 1 p的鸟苷二磷酸/鸟苷三磷酸交换因子，已经涉及自噬。在这项研究中，我们研究的作用，Sar 1 p在pexophagy表达显性负突变形式的Sar 1 p在毕赤酵母。当表达sar 1 pT 34 N或sar 1 pH 79 G时，饥饿诱导的自噬、葡萄糖诱导的微噬和乙醇诱导的巨噬都被显著抑制。这些Sar 1 p突变体不影响的启动或扩展的隔离膜，也不贩运Atg 11 p和Atg 9 p这些膜在micropexophagy。然而，脂化的Atg 8 p和组装的micropexophagic膜装置，这是必不可少的，以完成过氧化物酶体纳入降解泡，被抑制时，无论是Sar 1 p突变蛋白的表达。在巨噬细胞吞噬过程中，sar 1 pT 34 N的表达抑制了吞噬体的形成，而sar 1 pH 79 G抑制了过氧化物酶体从吞噬体向液泡的传递。在野生型细胞中，pexophagosome含有Atg 8 p，但在表达sar 1 pH 79 G的细胞中，这些细胞器含有Atg 8 p和内质网组分，如DsRFP-HDEL所示。我们的研究结果表明，在微观和macropexophagy的Sar 1 p的关键作用。
Several Sec proteins including a guanosine diphosphate/guanosine triphosphate exchange factor for Sar1p have been implicated in autophagy. In this study, we investigated the role of Sar1p in pexophagy by expressing dominant-negative mutant forms of Sar1p inPichia pastoris. When expressing sar1pT34N or sar1pH79G, starvation-induced autophagy, glucose-induced micropexophagy, and ethanol-induced macropexophagy are dramatically suppressed. These Sar1p mutants did not affect the initiation or expansion of the sequestering membranes nor the trafficking of Atg11p and Atg9p to these membranes during micropexophagy. However, the lipidation of Atg8p and assembly of the micropexophagic membrane apparatus, which are essential to complete the incorporation of the peroxisomes into the degradative vacuole, were inhibited when either Sar1p mutant protein was expressed. During macropexophagy, the expression of sar1pT34N inhibited the formation of the pexophagosome, whereas sar1pH79G suppressed the delivery of the peroxisome from the pexophagosome to the vacuole. The pexophagosome contained Atg8p in wild-type cells, but in cells expressing sar1pH79G these organelles contain both Atg8p and endoplasmic reticulum components as visualized by DsRFP-HDEL. Our results demonstrate key roles for Sar1p in both micro- and macropexophagy.