Atg17 functions in cooperation with Atg1 and Atg13 in yeast autophagy
Atg17 functions in cooperation with Atg1 and Atg13 in yeast autophagy
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DOI：
10.1091/mbc.e04-08-0669
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发表时间：
2005-05-01
影响因子：
3.3
通讯作者：
Ohsumi, Y
中科院分区：
文献类型：
--
作者：
Kabeya, Y;Kamada, Y;Ohsumi, Y
在真核细胞中，营养饥饿诱导细胞物质的大量降解;这个过程被称为自噬。在酿酒酵母中，大多数ATG（自噬）基因不仅参与降解性自噬过程，而且参与生物合成过程，即细胞质到液泡（Cvt）途径。相比之下，ATG 17基因在自噬中特异性地需要。为了更好地理解Atg 17的功能，我们对Atg 17蛋白进行了生化表征。我们发现atg 17 Delta突变体在饥饿条件下自噬体的形成在很大程度上受损，并且很少含有小的自噬体，其尺寸小于正常自噬体直径的一半。双杂交分析和免疫共沉淀实验表明，Atg 17与Atg 1-Atg 13复合物物理缔合，并且这种结合在饥饿条件下增强。在atg 13 Delta突变细胞中未检测到Atg 17-Atg 1结合，表明Atg 17通过Atg 13与Atg 1相互作用。Atg 17的点突变体Atg 17（C24 R）显示出对Atg 13的亲和力降低，导致Atg 1激酶活性受损和自噬的显着缺陷。综上所述，这些结果表明，Atg 17-Atg 13复合物的形成通过结合并激活Atg 1激酶在正常的自噬体形成中起重要作用。
In eukaryotic cells, nutrient starvation induces the bulk degradation of cellular materials; this process is called autophagy. In the yeast Saccharomyces cerevisiae, most of the ATG (autophagy) genes are involved in not only the process of degradative autophagy, but also a biosynthetic process, the cytoplasm to vacuole (Cvt) pathway. In contrast, the ATG17 gene is required specifically in autophagy. To better understand the function of Atg17, we have performed a biochemical characterization of the Atg17 protein. We found that the atg17 Delta mutant under starvation condition was largely impaired in autophagosome formation and only rarely contained small autophagosomes, whose size was less than one-half of normal autophagosomes in diameter. Two-hybrid analyses and coimmunoprecipitation experiments demonstrated that Atg17 physically associates with Atg1-Atg13 complex, and this binding was enhanced under starvation conditions. Atg17-Atg1 binding was not detected in atg13 Delta mutant cells, suggesting that Atg17 interacts with Atg1 through Atg13. A point mutant of Atg17, Atg17(C24R), showed reduced affinity for Atg13, resulting in impaired Atg1 kinase activity and significant defects in autophagy. Taken together, these results indicate that Atg17-Atg13 complex formation plays an important role in normal autophagosome formation via binding to and activating the Atg1 kinase.