Structure and Function of Direct Delivery Peptides

摘要 膜中蛋白质折叠的经典概念在许多年前就已阐明，现在可以在 教科书。然而，我们已经观察到自组装的多肽纳米孔结构，具有许多潜在的应用， 这些经典概念不能完全解释这一点。自组装的螺旋纳米孔，形式 双层膜中的大分子尺寸的孔，直径大于5 nm。这些多肽似乎并不是 疏水性足以插入跨膜结构，但它们确实做到了这一点。我们将测试这一想法 纳米孔在双层中的稳定性可以通过肽、脂类、 以及孔内的水，以及与双层的经典疏水相互作用。这个 我们将研究的纳米孔是通过螺旋多肽的自组装形成的，这些螺旋多肽已经通过 合成分子进化(几代迭代文库设计和筛选)。阐释非经典 支配这些纳米孔自组装和稳定的相互作用将揭示出根本上的新奇 两亲性多肽和蛋白质在膜中的结构和自组装原理将是 扩张型氢键网络在跨膜稳定中作用的首次定量表征 毛孔。在拟议的工作中，我们将量化i)多肽纳米孔结构和功能是如何受 H-键网络中关键残基的靶向取代和可能的pH传感器，以及II)How肽 多肽疏水残基和膜物理变化对纳米孔结构和功能的影响 性质，如脂质成分所定义的。原子分子动力学模拟将贯穿始终 这项工作对实验的设计和解释具有一定的指导意义。通过理解序列结构-- 纳米孔形成的函数关系，包括pH敏感和膜选择性，我们将使 未来针对特定应用的纳米孔优化。我们设想在生物技术和医学中的应用，用于 便捷的蛋白质治疗、药物或大分子输送、抗癌活性等。

Summary Classical concepts of protein folding in membranes were elucidated many years ago and can now be found in textbooks. Yet, we have observed self-assembled peptide nanopore structures, with many potential applications, that cannot be fully explained by these classical concepts. The self-assembled helical nanopores, form macromolecule-sized pores in bilayers with diameters greater than 5 nm. The peptides appear not to be hydrophobic enough to insert into membrane-spanning structures, yet they do exactly that. We will test the idea that nanopore stability in the bilayer can be explained by cooperative H-bond networks between peptides, lipids, and water on the interior of the pore, in addition to classical hydrophobic interactions with the bilayer. The nanopores we will study are formed through the self-assembly of helical peptides that have been evolved through synthetic molecular evolution (generations of iterative library design and screening). Elucidating the nonclassical interactions that govern the self-assembly and stabilization of these nanopores will reveal fundamentally novel principles of the structure and self-assembly of amphipathic peptides and proteins in membranes and will be the first quantitative characterization of the role of expansive H-bond networks in the stabilization of transmembrane pores. In the proposed work, we will quantify i) how peptide nanopore structure and function are affected by targeted substitution of critical residues in the H-bond network and putative pH-sensor, and ii) how peptide nanopore structure and function are affected by changes in peptide hydrophobic residues and membrane physical properties, as defined by lipid composition. Atomistic molecular dynamics simulations will be used throughout this work to guide the design and the interpretation of experiments. By understanding the sequence-structure- function relationships of nanopore formation, including pH-sensing and membrane selectivity, we will enable future nanopore optimization for specific applications. We envision usage in biotechnology and medicine, for facile protein therapy, drug or macromolecule delivery, anticancer activity, and more.