Kent Fungal Group, School of Biosciences, University of Kent, Canterbury, Kent CT2 7NJ, UK.
Mol Cell. 2013 Jun 6;50(5):675-85. doi: 10.1016/j.molcel.2013.05.010.
Prions are propagated in Saccharomyces cerevisiae with remarkable efficiency, yet we know little about the structural basis of sequence variations in the prion protein that support or prohibit propagation of the prion conformation. We show that certain single-amino-acid substitutions in the prion protein Sup35 impact negatively on the maintenance of the associated prion-based [PSI(+)] trait by combining in vivo phenotypic analysis with solution NMR structural studies. A clear correlation is observed between mutationally induced conformational differences in one of the oligopeptide repeats (R2) in the N terminus of Sup35 and the relative ability to propagate [PSI(+)]. Strikingly, substitution of one of a Gly-Gly pair with highly charged residues that significantly increase structural definition of R2 lead to a severe [PSI(+)] propagation defect. These findings offer a molecular explanation for the dominant-negative effects of such psi-no-more (PNM) mutations and demonstrate directly the importance of localized structural definition in prion propagation.
朊病毒在酿酒酵母中的传播效率非常高，但我们对支持或阻止朊病毒构象传播的朊病毒蛋白序列变异的结构基础知之甚少。我们通过将体内表型分析与溶液 NMR 结构研究相结合，表明朊病毒蛋白 Sup35 中的某些单个氨基酸取代会对维持相关的基于朊病毒的 [PSI(+)]特性产生负面影响。在 Sup35 N 端的一个寡肽重复 (R2) 中，观察到突变诱导的构象差异与相对传播 [PSI(+)]的能力之间存在明显的相关性。引人注目的是，用带正电荷的残基取代一对高度保守的 Gly-Gly 对，显著增加了 R2 的结构清晰度，导致 [PSI(+)]传播缺陷严重。这些发现为这种 psi-no-more (PNM) 突变的显性负效应提供了分子解释，并直接证明了局部结构定义在朊病毒传播中的重要性。
