DEFENSINS, BACTENECINS AND PERIODONTAL DISEASES

防御素、杆菌肽和牙周疾病

• 批准号: 6104699
• 负责人: ANTONY R PERIATHAMBY
• 金额: $ 16.97万
• 依托单位: STATE UNIVERSITY OF NEW YORK AT BUFFALO
• 依托单位国家: 美国
• 财政年份: 1998
• 资助国家: 美国
• 起止时间: 1998-08-01 至 2000-04-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6104699
• 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.

该项目的远距离目标是系统地研究 “防御蛋白和bactenecins”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，发展和 评估一种新的无毒抗生素，用于防御 牙周病原体，包括肌动杆菌肌动症和 牙龈卟啉单胞菌和机会性病原体（例如 白色念珠菌。 防御素和bactenecin被输送到含有液泡的液泡 吞噬作用期间摄入的微生物，并释放到 当嗜中性粒细胞被促分泌物刺激时，细胞外液。 它们与微生物的膜相互作用，改变膜渗透性 和离子梯度，并进一步导致损害的功能 内部呼吸链和其他依赖能量的活动 膜。 他们在宿主防御，炎症和 通过杀死的能力来恢复改变的稳态状况 入侵微生物。 这表明选择这些理由 我们目前研究的分子和这些分子的重要性 在控制包括牙周在内的这些生物的口腔感染时 疾病。 高度保守的二硫化物，甘氨酸和带电的残留物 防御蛋白，以及一个由单个的重复pro-arg-pro三胞胎 疏水性残留物中的bactenecins，为这些提供刚性结构 分子克服自适应微生物对有机的耐药性 抗生素。 这些独特的保守结构元素也暗示 它们的杀生功能确实取决于特定 结构特征和特定的电荷分布。 结构 在这些多肽的主要序列中观察到的多样性是 反映出其生物活性的广泛变化。 这 功能多样性显然是由于微妙变化的结果 这些大小，序列，精细的结构基序和侧链地形 分子。 该项目涉及防御素，bactenecin和 化学和基因工程技术的肽类似物， 通过光谱法（NMR，FTIR，CD）确定结构 计算机建模和晶体结构分析，并评估 这些分子的体外cidal活性。 从结构功能分析获得的信息将 允许立体化学约束肽的设计和合成 防御蛋白和bactenecin的类似物，这些类似物可能会增强和 长期活性。 这些新的口服抗生素可能对 控制和治疗牙周疾病和其他口腔感染。 此外，分子生物学研究将描绘cDNA和 编码活性类似物序列的重组DNA并引导 针对类似临床应用的基因治疗方法。