DEFENSINS, BACTENECINS AND PERIODONTAL DISEASES

防御素、杆菌肽和牙周疾病

• 批准号: 6238374
• 负责人: ANTONY R PERIATHAMBY
• 金额: $ 25.62万
• 依托单位: STATE UNIVERSITY OF NEW YORK AT BUFFALO
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-08-01 至 2000-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6238374
• 关键词: Actinobacillus actinomycetemcomitans; Bacteroides gingivalis; Candida albicans; X ray crystallography; antibiotics; bactericidal immunity; chemical stability; chemical substitution; chemoattractants; circular dichroism; conformation; drug design /synthesis /production; human tissue; infrared spectrometry; neutrophil; nuclear magnetic resonance spectroscopy; peptide analog; peptide chemical synthesis; periodontitis; polymerase chain reaction; protein sequence; protein structure function; recombinant DNA; site directed mutagenesis; synthetic peptide

The long range goal of this project is to systematically study the structural and molecular biology of "defensins and bactenecins", the antimicrobial cationic polypeptides present in the granules of neutrophils. These studies will help identify, design, develop and evaluate a new class of nontoxic antibiotics to be used to defend against periodontal pathogens including Actinobacillus actinomycetemcomitans and Porphyromonas gingivalis as well as opportunistic pathogens such as Candida albicans. Defensins and bactenecins are delivered to vacuoles containing the ingested microorganisms during phagocytosis and are released into the extracellular fluids when neutrophils are stimulated by secretagogues. They interact with the membranes of microbes, alter membrane permeability and ionic gradient, and further cause impairment of the function of the respiratory chain and other energy dependent activities in the inner membranes. They play a major role in host defense, inflammation and restoration of the altered homeostatic condition by their ability to kill invading microbes. This suggests a rationale for selection of these molecules for our present studies and the importance of these molecules in controlling oral infections by these organisms including periodontal disease. The highly conserved disulfides, glycines and the charged residues in defensins, and the repeating Pro-Arg-Pro triplets spaced by a single hydrophobic residue in bactenecins, provide rigid structures for these molecules to overcome the adaptive microbial resistance to organic antibiotics. These unique conserved structural elements also suggest that their microbicidal functions are indeed dependent on a specific structural feature and a particular charge distribution. The structural diversity observed in the primary sequence of these polypeptides is reflected in wide variations in their biological activity. This functional diversity is clearly a consequence of subtle variations in the size, sequence, fine structural motifs and side-chain topography of these molecules. This project involves synthesis of defensins, bactenecins and peptide analogs by both chemical and genetic engineering techniques, structure determination by spectroscopic methods (NMR, FTIR, CD), computer modeling and crystal structure analysis, and assessment of in vitro cidal activity of these molecules. The information to be obtained from structure-function analyses will permit the design and synthesis of stereochemically constrained peptide analogs of defensins and bactenecins which could elicit enhanced and prolonged activity. These new oral antibiotics may be useful for the control and treatment of periodontal disease and other oral infections. In addition, the molecular biology studies would delineate the cDNA and the recombinant DNA encoding the sequences of the active analogs and lead to gene therapy approaches for similar clinical applications.

该项目的长期目标是系统地研究 “防御素和细菌素”的结构和分子生物学， 存在于颗粒中的抗菌阳离子多肽 中性粒细胞。 这些研究将有助于识别、设计、开发和 评估一类新型无毒抗生素，用于防御 牙周病原体包括放线放线杆菌和 牙龈卟啉单胞菌以及机会致病菌，例如 白色念珠菌。 防御素和细菌素被递送到含有 微生物在吞噬过程中被摄入并释放到 当中性粒细胞受到促分泌剂刺激时产生细胞外液。 它们与微生物膜相互作用，改变膜渗透性 和离子梯度，并进一步导致功能受损 呼吸链和其他内部能量依赖活动 膜。 它们在宿主防御、炎症和 通过杀伤能力恢复改变的体内平衡状态 入侵微生物。 这表明了选择这些的理由 我们目前研究的分子以及这些分子的重要性 控制这些微生物（包括牙周病）引起的口腔感染 疾病。 高度保守的二硫化物、甘氨酸和带电残基 防御素，以及由单个间隔的重复 Pro-Arg-Pro 三联体 bactenecins 中的疏水残基，为这些提供刚性结构 克服微生物对有机物的适应性抗性的分子 抗生素。 这些独特的保守结构元素也表明 它们的杀菌功能确实依赖于特定的 结构特征和特定的电荷分布。 结构性 在这些多肽的一级序列中观察到的多样性是 反映在其生物活性的巨大差异上。 这 功能多样性显然是细微变化的结果 这些的大小、序列、精细结构图案和侧链拓扑 分子。 该项目涉及防御素、细菌素和 通过化学和基因工程技术制备肽类似物， 通过光谱方法（NMR、FTIR、CD）确定结构， 计算机建模和晶体结构分析以及评估 这些分子的体外杀伤活性。 从结构-功能分析中获得的信息将 允许设计和合成立体化学限制的肽 防御素和细菌素的类似物，可以引起增强和 长时间的活动。 这些新的口服抗生素可能有助于 控制和治疗牙周病和其他口腔感染。 此外，分子生物学研究将描述 cDNA 和 编码活性类似物和先导序列的重组DNA 用于类似临床应用的基因治疗方法。