Structure and function of antimicrobial peptides

描述（由申请人提供）：随着越来越多的细菌菌株对现有的常规抗生素产生耐药性，开发新的活性治疗剂变得越来越重要。天然抗菌肽是真核细胞对抗细菌、原生动物、真菌和病毒的一种成功的化学防御形式。抗菌肽通过破坏细菌的膜来杀死细菌，这些肽可能成为抵抗传染病的新防线。本研究的主要目的是了解人抗菌肽LL37及其衍生物的作用机制和选择性。结构、动力学和热力学研究的结合将用于研究膜破坏的机制，以及重要的脂质-肽和肽-肽相互作用，这些相互作用决定了细菌而不是真核生物膜破坏的特异性。这些研究的主要分析工具是固态核磁共振波谱，使用了一套非常适合于非晶体膜系统的原子水平结构研究的技术。我们将获得以下关于抗菌肽膜破坏机制的高分辨率结构信息：(i)二级结构；（ii）相对于膜双分子层正常值的取向；（三）膜破坏的动力学和机制。从这三种类型的测量数据将被结合起来，以获得膜结合抗菌肽的详细图片。实验将采用多种固态核磁共振方法来测量化学位移和偶极耦合参数。抗菌肽也将在溶液中（在膜插入之前）和胶束中使用圆二色性和溶液核磁共振实验进行表征。差示扫描量热法、氘核磁共振和磷-31核磁共振实验也将用于探测与抗菌肽相互作用时脂质运动动力学的局部和全局变化。本研究旨在进一步了解抗菌肽的基本功能，开发出比LL37或相关肽更有效和选择性的新肽类。这些肽具有作为抗生素的治疗潜力，对囊性纤维化患者尤其重要。

DESCRIPTION (provided by applicant): The development of new active therapeutic agents is of increasing importance as more bacterial strains resistant to existing conventional antibiotics are emerging. Natural antimicrobial peptides represent one successful form of chemical defense that eukaryotic cells use against bacteria, protozoa, fungi, and virus. Antimicrobial peptides kill bacteria by disrupting their membranes, and these peptides may be developed into a new line of defense against infectious diseases. The main goal of the proposed research is to understand the mechanism and selectivity of a human antimicrobial peptide, LL37, and its derivatives. A combination of structural, dynamics, and thermodynamic studies will be used to investigate the mechanism of membrane-disruption, and the important lipid-peptide and peptide-peptide interactions that determine the specificity for disruption of bacterial rather than eukaryotic membranes. The main analytical tool in these studies is solid-state NMR spectroscopy, using a set of techniques which are well-suited to atomic-level structural studies in non-crystalline membrane systems. We will obtain the following high-resolution structural information about the membrane-disrupting mechanism of antimicrobial peptides: (i) secondary structure; (ii) orientation relative to the membrane bilayer normal; and (iii) dynamics and mechanism of membrane-disruption. The data from these three types of measurements will be combined to obtain a detailed picture of the membrane-bound antimicrobial peptides. The experiments will employ a variety of solid-state NMR methods in order to measure chemical shift and dipolar coupling parameters. Antimicrobial peptides will also be characterized in solution (prior to membrane insertion) and in micelles using circular dichroism and solution NMR experiments. Differential scanning calorimetry, deuterium NMR, and phosphorous-31 NMR experiments will also be used to probe local as well as global changes in lipid motional dynamics upon interaction with the antimicrobial peptides. This proposal aims to further our fundamental understanding of the antimicrobial peptide function to develop a new class of peptides that are more potent and selective than LL37 or related peptides. These peptides have therapeutic potential as antibiotics and have particular importance for cystic fibrosis patients.