Revault M, Quiquampoix H, Baron M H, Noinville S
Laboratoire de Dynamique, Interactions et Réactivité CNRS-Université Pierre et Marie Curie, UMR 7075, 2 rue Henri Dunant, 94320 Thiais, France.
Biochim Biophys Acta. 2005 Aug 5;1724(3):367-74. doi: 10.1016/j.bbagen.2005.05.005.
Studying the mechanism of retention of ovine prion protein in soils will tackle the environmental aspect of potential dissemination of scrapie infectious agent. We consider the surface-induced conformational changes that the recombinant ovine prion protein (ovPrP) may undergo under different pH conditions when interacting with soil minerals of highly adsorptive capacities such as montmorillonite. The conformational states of the full-length ovine prion protein adsorbed on the electronegative clay surface are compared to its solvated state in deuterated buffer in the pD range 3.5-9, using FTIR spectroscopy. The in vitro pH-induced conversion of the alpha-helical monomer of ovPrP into oligomers of beta-like structure prone to self-aggregation does not occur when the protein is adsorbed on the clay surface. The conformation of the trapped ovPrP molecules on montmorillonite is pH-independent and looks like that of the ovPrP solvated state at pD higher than 7, suggesting the major role of Arg and Lys residues in the electrostatic origin of adsorption. The uneven distribution of positively and negatively charged residues of the ovPrP protein would promote a favored orientation of the protein towards the clay, so that not only the basic residues embedded in the N-terminal flexible part but also external basic residues in the globular part of the protein might participate to the attractive interaction. From these results, it appears unlikely that the interaction of normal prions (PrP(C)) with soil clay surfaces could induce a change of conformation leading to the pathogenic form of prions (PrP(Sc)).
研究绵羊朊病毒蛋白在土壤中的留存机制将解决羊瘙痒病感染因子潜在传播的环境问题。我们考虑重组绵羊朊病毒蛋白（ovPrP）在与具有高吸附能力的土壤矿物质（如蒙脱石）相互作用时，在不同pH条件下可能发生的表面诱导构象变化。使用傅里叶变换红外光谱法，将吸附在带负电的粘土表面的全长绵羊朊病毒蛋白的构象状态与其在pD范围为3.5 - 9的氘代缓冲液中的溶剂化状态进行比较。当蛋白质吸附在粘土表面时，体外pH诱导的ovPrPα - 螺旋单体向易于自我聚集的β样结构寡聚体的转化不会发生。蒙脱石上捕获的ovPrP分子的构象与pH无关，并且看起来像pD高于7时ovPrP的溶剂化状态，这表明Arg和Lys残基在吸附的静电起源中起主要作用。ovPrP蛋白带正电和负电残基的不均匀分布将促进蛋白质朝向粘土的有利取向，这样不仅嵌入N端柔性部分的碱性残基，而且蛋白质球状部分的外部碱性残基也可能参与吸引相互作用。从这些结果来看，正常朊病毒（PrP(C)）与土壤粘土表面的相互作用似乎不太可能诱导构象变化从而导致朊病毒的致病形式（PrP(Sc)）。
