STRUCTURAL STUDIES ON TRANSMEMBRANE PRION PROTEIN

PrP生物发生的一个显著特征是观察到新生PrP是以至少三种不同的跨膜拓扑结构的形式合成的，这似乎是理解PrP疾病病理生理学的核心。越来越多的证据表明，其中一种被称为(CTM)PrP，它触发了一条最终的共同的凋亡途径，对遗传性和感染性Prion疾病做出反应，而另一种构象，被称为(SEC)PrP，具有抗凋亡和神经保护作用。过去十年的研究揭示了许多方法，通过这些方法， 从初始均一的新生PrP链群体合成的PrP可以改变。特别是，信号序列和紧接在跨膜区之前的被称为停止转移效应(STE)序列的带电区域已经被证明是PrP拓扑的序列决定因素。最近的数据表明：1)除信号序列和STE序列外，其他区域可能参与PrP跨膜拓扑和构象的调节；2)PrP内部不同结构域的相互作用参与蛋白质的拓扑发生；3)易位过程中蛋白质-蛋白质相互作用的定位可能为构象操作提供有用的信息。在这里，我们提出的研究目的是i)探索新的拓扑发生序列及其在顺式基因中的相互作用，以及ii)确定合作伙伴 新生PrP参与反式作用的蛋白质。然后，我们将利用这些信息来更好地理解产生单个PrP构象的机制，以及这些机制与感染性瘙痒病信号的关系。从长远来看，这项工作还可能开发出通过构象操纵来治疗普恩病毒疾病的新方法。

A distinctive feature of prion protein (PrP) biogenesis, which appears central to an understanding of prion disease pathophysiology, is the observation that nascent PrP is synthesized in the form of at least three distinctive conformers that also differ in transmembrane topology. A growing body of evidence suggests that one of these, termed (Ctm)PrP, triggers a final common pathway of apoptosis occurring in response to both genetic and infectious prion disease, while another conformer, termed (Sec)PrP, is anti-apoptotic and neuroprotective. Work over the last decade has revealed a number of means by which the mix of conformers synthesized from an initially homogeneous population of nascent PrP chains can be altered. In particular, the signal sequence, and a charged region termed the Stop Transfer Effector (STE) sequence immediately preceding the transmembrane region, have been demonstrated to be sequence determinants of PrP topology. More recent data suggests that: i) other regions besides the signal sequence and STE sequence may contribute to regulation of PrP transmembrane topology and conformation, ii) interaction of distinct domains within PrP are involved in the protein's topogenesis, and iii) mapping of protein-protein interactions during translocation may provide useful information for conformer manipulation. Here we propose studies designed to i) explore new topogenic sequences and their interactions in cis, and ii) identify the partner proteins with which nascent PrP is involved in trans. We will then use this information to better understand the mechanism by which individual PrP conformers are generated, and the relationship of those mechanisms to signaling in infectious scrapie. In the long run, this work may also make possible the development of novel approaches to treatment of prion disease through conformer manipulation.