In vivo aggregation of the HET-s prion protein of the fungus Podospora anserina
In vivo aggregation of the HET-s prion protein of the fungus Podospora anserina
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DOI：
10.1046/j.1365-2958.2001.02707.x
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发表时间：
2001-12-01
影响因子：
3.6
通讯作者：
Saupe, SJ
中科院分区：
文献类型：
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作者：
Coustou-Linares, V;Maddelein, ML;Saupe, SJ
我们提出丝状真菌[Het-S]侵染的细胞质元件是Het-S蛋白的Prion形式。Het-S蛋白参与了丝状真菌的一种细胞识别现象，称为异核体不亲和性。在Prion形式下，Het-S蛋白与Het-S蛋白共表达时会引起细胞死亡反应，只有13个氨基酸残基不同。我们在这里证明了HET-S蛋白在体内可以以可溶和聚集两种状态存在。如酵母普里恩所示，转变为具有感染性的普恩形式会导致热休克蛋白-S-绿色荧光蛋白融合蛋白的聚集。HET-S蛋白在高表达时在体内聚集。然而，我们不能证明hET-S在野生型表达水平上的聚集，这可能表明在野生型[het-S]菌株中只有一小部分hET-S蛋白在体内以聚集的形式存在。拮抗的hET-S形式即使在高表达水平也是可溶的。Het-S(D23A P33H)上的双氨基酸取代消除了PrP的感染性，抑制了GFP融合蛋白的体内聚集。综上所述，这些结果进一步支持了[Het-S]元素对应于Het-S蛋白的一种异常的自持续聚集形式的模型。
We have proposed that the [Het-s] infectious cytoplasmic element of the filamentous fungus Podospora anserina is the prion form of the HET-s protein. The HET-s protein is involved in a cellular recognition phenomenon characteristic of filamentous fungi and known as heterokaryon incompatibility. Under the prion form, the HET-s protein causes a cell death reaction when co-expressed with the HET-S protein, from which it differs by only 13 amino acid residues. We show here that the HET-s protein can exist as two alternative states, a soluble and an aggregated form in vivo. As shown for the yeast prions, transition to the infectious prion form leads to aggregation of a HET-s-green fluorescent protein (GFP) fusion protein. The HET-s protein is aggregated in vivo when highly expressed. However, we could not demonstrate HET-s aggregation at wild-type expression levels, which could indicate that only a small fraction of the HET-s protein is in its aggregated form in vivo in wild-type [Het-s] strains. The antagonistic HET-S form is soluble even at high expression level. A double amino acid substitution in HET-s (D23A P33H), which abolishes prion infectivity, suppresses in vivo aggregation of the GFP fusion. Together, these results further support the model that the [Het-s] element corresponds to an abnormal self-perpetuating aggregated form of the HET-s protein.