Functional and biochemical analysis of oligomeric intermediates of yeast prions formed in vivo

一个多世纪以来，孟德尔的遗传定律几乎被普遍接受，用来解释遗传信息如何忠实地从一代传到下一代。一个基于核酸的遗传单位，即基因，携带着这种信息，生物体的特征是由它的一组基因定义的。在过去的一个世纪里，人们已经发现了孟德尔定律的一些例外情况，但最近由于普恩的发现，对所有遗传都是基于核酸的教条提出了新的挑战。尽管作为与疯牛病和人类相对应的克雅氏病(CJD)相关的致病因子，普恩病毒已经被深入研究，但现在有相当多的科学证据表明，普恩病毒实际上可能代表了一种全新的遗传形式，基于蛋白质分子而不是核酸。这一证据来自于对面包酵母(Saccharmyces Cerevisiae)中新的基于Prion的‘遗传’决定因素的分析，其中一个因素(所谓的[PSI+]元件)正在进行研究。我们的目标是充分了解这种基于蛋白质的决定簇是如何从头产生，然后在酵母细胞生长和分裂时复制并传递给其他酵母细胞的。我们知道，这需要细胞产生可以传递给其他细胞的Pron种子，我们的目标是确定这些种子的分子组成。利用先进的遗传和生物化学方法，我们将研究不同的酵母蛋白，特别是它们在形成蛋白的过程中所经历的物理变化。这项研究的一个结果可能是确定Pron周期中的步骤，这些步骤可以被新药靶向，以阻止Pron种子的形成。

For over a century there has been a near universal acceptance of Mendel's Laws of Inheritance to explain the faithful transmission of genetic information from one generation to the next. A nucleic acid-based hereditary unit, the gene, carries this information and the characteristics of an organism are defined by its set of genes. Over the last century a number of exceptions to Mendel's Laws have been identified, but a new challenge to the dogma that all inheritance is nucleic acid based has recently arisen from the discovery of prions. Although prions have been intensively studied as the disease-causing agents associated with 'Mad Cow Disease' and the human equivalent, Creutzfeldt-Jakob Disease (CJD), there is now a considerable body of scientific evidence that prions might actually represent an entirely new form of heredity, based on a protein molecule rather than a nucleic acid. This evidence comes from the analysis of novel prion-based 'genetic' determinants in Baker's Yeast (Saccharomyces cerevisiae) one of which (the so-called [PSI+] element) is being studied in this project. Our aim is to fully understand how such a protein-based determinant is generated de novo and then replicated aand passed on to other yeast cells when they grow and divide. We know that this requires cells to produce prion seeds which can be passed on to other cells and it is our objective to define the molecular composition of these seeds. Uisng advanced genetic and biochemical methods we will study different yeast prions and look in particular at the type of physical changes they go through in taking up their prion form. One outcome of this research might be identifying steps in the prion cycle that can be targetted by new drugs to block the formation of prion seeds.