Institute of Molecular Biology and Biophysics, Eidgenössische Technische Hochschule Zurich, Schafmattstrasse 20, CH-8093 Zurich, Switzerland.
Proc Natl Acad Sci U S A. 2011 Oct 18;108(42):17308-13. doi: 10.1073/pnas.1106325108. Epub 2011 Oct 10.
In the otherwise highly conserved NMR structures of cellular prion proteins (PrP(C)) from different mammals, species variations in a surface epitope that includes a loop linking a β-strand, β2, with a helix, α2, are associated with NMR manifestations of a dynamic equilibrium between locally different conformations. Here, it is shown that this local dynamic conformational polymorphism in mouse PrP(C) is eliminated through exchange of Tyr169 by Ala or Gly, but is preserved after exchange of Tyr 169 with Phe. NMR structure determinations of designed variants of mouse PrP(121-231) at 20 °C and of wild-type mPrP(121-231) at 37 °C together with analysis of exchange effects on NMR signals then resulted in the identification of the two limiting structures involved in this local conformational exchange in wild-type mouse PrP(C), and showed that the two exchanging structures present characteristically different solvent-exposed epitopes near the β2-α2 loop. The structural data presented in this paper provided a platform for currently ongoing, rationally designed experiments with transgenic laboratory animals for renewed attempts to unravel the so far elusive physiological function of the cellular prion protein.
在不同哺乳动物的细胞朊蛋白（PrP(C)）的高度保守的 NMR 结构中，包括连接β-链β2和螺旋α2的环的表面表位中的种属变异与局部不同构象之间的 NMR 表现出的动态平衡有关。在这里，已经表明，通过用丙氨酸或甘氨酸替换 Tyr169，可消除小鼠 PrP(C)中的这种局部动态构象多态性，但在 Tyr169被苯丙氨酸替换后仍保留这种构象多态性。在 20°C 下对设计的小鼠 PrP(121-231)变体和在 37°C 下对野生型 mPrP(121-231)进行 NMR 结构测定，并对 NMR 信号的交换效应进行分析，从而确定了在野生型小鼠 PrP(C)中涉及这种局部构象交换的两种极限结构，并表明这两种交换结构在β2-α2 环附近呈现出特征性不同的溶剂暴露表位。本文中提供的结构数据为目前正在进行的、基于理性设计的转基因实验提供了一个平台，以便重新尝试揭示细胞朊蛋白迄今为止难以捉摸的生理功能。
