Probing natural amyloid fibril assembly by protein display

生物的结构和物质是由自我组装的分子构成的，主要是蛋白质。蛋白质聚集体因与老年疾病（如阿尔茨海默病和帕金森病）有关而臭名昭著。在这些疾病中，蛋白质错误折叠并聚集成称为淀粉样原纤维的大绳状沉积物。事实证明，如果不是所有的蛋白质都可以折叠形成这些淀粉样蛋白细丝。原纤维具有非常规则的结构和一些显著的物理性质。事实证明，大自然已经进化出一些蛋白质，故意使它们处于这种状态，在细菌细胞表面制造原纤维，帮助细菌粘附在其他细胞上。这些是同类型纤维中最稳定的一些。淀粉样蛋白原纤维的规则和稳定的结构使它们成为悬挂其他功能性蛋白质的良好支架，这就是这个建议的基础。我们将使用在细菌细胞上形成天然淀粉样原纤维的蛋白质，并在基因水平上将它们融合到其他蛋白质和酶上。要做到这一点，我们需要更多地了解各个尺寸约为2纳米的单个蛋白质是如何组装成10纳米宽、10微米长的原纤维的。我们可以改变蛋白质的序列，观察原纤维是如何变化的。一旦我们对构建块的组装方式有了更多的了解，我们就会将其他蛋白质融合到构建块中，这样它们的功能就会在原纤维上显示出来。首先，我们将展示细胞中携带电子的蛋白质。这样我们就能制造出导电的淀粉样蛋白纤维。我们还将在原纤维上展示破坏抗生素的酶。这可以用来保护细胞免受抗生素的侵害，使细胞具有优势。这种特性可以用来进化原纤维，使其在技术上更有用。一旦我们确定了最佳类型的纤维和蛋白质展示方法，我们就可以随意制造纤维，并用它们来构建纳米尺度的纤维网络。这是一种利用完全自组装的分子构建电子和诊断分子装置的新方法。因此，尽管淀粉样蛋白在许多疾病状态下都是一个严重的问题，但它在制造分子电路方面也可能非常有用。

The structure and substance of living things are made from self-assembling molecules, primarily proteins. Protein aggregates have become notorious for being associated with some diseases of old age such as Alzheimer's and Parkinson's Diseases. In these disorders, proteins mis-fold and aggregate into large rope-like deposits known as amyloid fibrils. It turns out that most if not all proteins can fold to form these amyloid filaments. The fibrils have a very regular structure and some remarkable physical properties. It turns out that Nature has evolved some proteins to be in this state deliberately, to make fibrils on bacterial cell surfaces, to help bacteria stick to other cells. These are some of the most stable fibrils of their type. The regular and stable structure of amyloid fibrils makes them a good scaffold on which to hang other, functional proteins, and that is this basis of this proposal. We will use the proteins that form the natural amyloid fibrils on bacterial cells and fuse them, at the level of their genes, to other proteins and enzymes. To do this, we need to understand more about how individual proteins, which are about 2 nanometres in all dimensions, assemble to form fibrils that are 10 nanometres wide and 10 micrometres long. We can alter the protein's sequence and observe how the fibrils change. Once we have established more about how the building blocks are assembled, we will fuse other proteins to the building blocks so that their function becomes displayed on the fibrils. To start with we will display proteins that carry electrons around in cells. This way we can make a conducting amyloid fibril. We will also display on the fibrils enzymes that destroy antibiotics. This can be used to protect the cell against an antibiotic, giving the cell an advantage. This property can be used to evolve the fibrils to be more useful technologically. Once we have established the best type of fibril and protein display methods, we can then make fibrils at will and use them to build up networks of fibrils on the nanometre scale. This is a new approach to building molecular devices for electronics and diagnostics, out of completely self-assembling molecules. So while amyloid is a serious problem in many disease states, it may also be remarkably useful for making molecular circuits.