Institut de Biochimie et de Génétique Cellulaire, UMR 5095, CNRS - Université de Bordeaux 2, 1 rue Camille St Saens, 33077 Bordeaux cedex, France.
Mol Microbiol. 2011 Dec;82(6):1392-405. doi: 10.1111/j.1365-2958.2011.07893.x. Epub 2011 Nov 3.
HET-s is a prion protein of the filamentous fungus Podospora anserina. An orthologue of this protein, called FgHET-s has been identified in Fusarium graminearum. The region of the FgHET-s protein corresponding to the prion forming domain of HET-s, forms amyloid fibrils in vitro. These fibrils seed HET-s(218-289) fibril formation in vitro and vice versa. The amyloid fold of HET-s(218-289) and FgHET-s(218-289) are remarkably similar although they share only 38% identity. The present work corresponds to the functional characterization of the FgHET-s(218-289) region as a prion forming domain in vivo. We show that FgHET-s(218-289) is capable of prion propagation in P. anserina and is able to substitute for the HET-s PFD in the full-length HET-s protein. In accordance with the in vitro cross-seeding experiments, we detect no species barrier between P. anserina and F. graminearum PFDs. We use the yeast Saccharomyces cerevisiae as a host to compare the prion performances of the two orthologous PFDs. We find that FgHET-s(218-289) leads to higher spontaneous prion formation rates and mitotic prion stability than HET-s(218-289). Then we analysed the outcome of HET-s(218-289)/FgHET-s(218-289) coexpression. In spite of the cross-seeding ability of HET-s(218-289) and FgHET-s(218-289), in vivo, homotypic polymerization is favoured over mixed fibril formation.
Het-s 是丝状真菌 Podospora anserina 的朊病毒蛋白。在禾谷镰刀菌中鉴定到该蛋白的同源物，称为 FgHET-s。FgHET-s 蛋白中与 HET-s 的形成朊病毒结构域相对应的区域，在体外形成淀粉样纤维。这些纤维在体外引发 HET-s(218-289)纤维形成，反之亦然。尽管 HET-s(218-289)和 FgHET-s(218-289)仅共享 38%的同一性，但它们的淀粉样折叠非常相似。目前的工作对应于 FgHET-s(218-289)区域作为体内形成朊病毒结构域的功能表征。我们表明，FgHET-s(218-289)能够在 P. anserina 中进行朊病毒传播，并能够替代全长 HET-s 蛋白中的 HET-s PFD。与体外交叉接种实验一致，我们在 P. anserina 和 F. graminearum PFDs 之间没有发现种间障碍。我们使用酵母 Saccharomyces cerevisiae 作为宿主来比较这两个同源 PFD 的朊病毒性能。我们发现，与 HET-s(218-289)相比，FgHET-s(218-289)导致更高的自发朊病毒形成率和有丝分裂朊病毒稳定性。然后，我们分析了 HET-s(218-289)/FgHET-s(218-289)共表达的结果。尽管 HET-s(218-289)和 FgHET-s(218-289)具有交叉接种能力，但在体内，同型聚合比混合纤维形成更有利。
