Structure and Function of Direct Delivery Peptides

总结 膜中蛋白质折叠的经典概念在许多年前就被阐明，现在可以在 教科书然而，我们已经观察到自组装的肽纳米孔结构，具有许多潜在的应用， 这些经典概念无法完全解释的问题。自组装的螺旋纳米孔形成 在双层中具有直径大于5 nm的大分子大小的孔。这些肽似乎不是 疏水性足以插入跨膜结构，但它们确实做到了。我们将测试这个想法 双层中的纳米孔稳定性可以通过肽，脂质， 和水在孔的内部，除了与双层的经典疏水相互作用。的 我们将研究的纳米孔是通过螺旋肽的自组装形成的， 合成分子进化（迭代文库设计和筛选的世代）。阐释非经典 控制这些纳米孔的自组装和稳定化的相互作用将从根本上揭示新的 原理的结构和自组装的两亲性肽和蛋白质在膜，将是 第一个定量表征的作用，扩大氢键网络的稳定跨膜 毛孔在拟议的工作中，我们将量化i）肽纳米孔结构和功能如何受到 H-键网络和推定的pH传感器中关键残基的靶向取代，以及ii）肽如何 纳米孔的结构和功能受到肽疏水残基和膜物理性质的变化的影响。 性质，如脂质组成所定义。原子分子动力学模拟将被用于整个 这项工作，以指导设计和解释的实验。通过了解序列结构- 纳米孔形成的功能关系，包括pH传感和膜选择性，我们将使 用于特定应用的未来纳米孔优化。我们设想在生物技术和医学中的应用， 简单的蛋白质治疗、药物或大分子递送、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.