Laboratory of Physical Chemistry, Swiss Federal Institute of Technology, ETH-Hönggerberg, CH-8093 Zürich, Switzerland.
Laboratory of Physical Chemistry, Swiss Federal Institute of Technology, ETH-Hönggerberg, CH-8093 Zürich, Switzerland.
J Mol Biol. 2018 Oct 12;430(20):3735-3750. doi: 10.1016/j.jmb.2018.05.046. Epub 2018 Jun 8.
How life can emerge from non-living matter is one of the fundamental mysteries of the universe. A bottom-up approach to this problem focuses on the potential chemical precursors of life, in particular the nature of the first replicative molecules. Such thinking has led to the currently most popular idea: that an RNA-like molecule played a central role as the first replicative and catalytic molecule. Here, we review an alternative hypothesis that has recently gained experimental support, focusing on the role of amyloidogenic peptides rather than nucleic acids, in what has been by some termed "the amyloid-world" hypothesis. Amyloids are well-ordered peptide aggregates that have a fibrillar morphology due to their underlying structure of a one-dimensional crystal-like array of peptides in a β-strand conformation. While they are notorious for their implication in several neurodegenerative diseases including Alzheimer's disease, amyloids also have many biological functions. In this review, we will elaborate on the following properties of amyloids in relation to their fitness as a prebiotic entity: they can be formed by very short peptides with simple amino acids sequences; as aggregates they are more chemically stable than their isolated component peptides; they can possess diverse catalytic activities; they can form spontaneously during the prebiotic condensation of amino acids; they can act as templates in their own chemical replication; they have a structurally repetitive nature that enables them to interact with other structurally repetitive biopolymers like RNA/DNA and polysaccharides, as well as with structurally repetitive surfaces like amphiphilic membranes and minerals.
生命如何从非生命物质中产生是宇宙的基本奥秘之一。一种自下而上的方法侧重于生命的潜在化学前体，特别是第一个复制分子的性质。这种思维导致了目前最流行的观点：一种类似 RNA 的分子在作为第一个复制和催化分子方面发挥了核心作用。在这里，我们回顾了一个最近得到实验支持的替代假设，重点关注淀粉样肽而不是核酸的作用，这在一些人称为“淀粉样蛋白世界”假说中有所体现。淀粉样蛋白是有序的肽聚集物，由于其下结构是一维晶体状的肽排列在β-折叠构象中，因此具有纤维状形态。虽然它们因与包括阿尔茨海默病在内的几种神经退行性疾病有关而声名狼藉，但淀粉样蛋白也具有许多生物学功能。在这篇综述中，我们将详细阐述淀粉样蛋白与它们作为前生物实体的适应性有关的以下特性：它们可以由具有简单氨基酸序列的非常短的肽形成；作为聚集物，它们比其分离的组成肽更具化学稳定性；它们可以具有多种催化活性；它们可以在氨基酸的前生物缩合过程中自发形成；它们可以在自身的化学复制中充当模板；它们具有结构重复的性质，使它们能够与其他结构重复的生物聚合物（如 RNA/DNA 和多糖）以及具有结构重复的表面（如两亲性膜和矿物质）相互作用。
