Salivary MUC7 Antimicrobial Peptide:RIM101 Response and Mechanism of Action.

描述（由申请人提供）：阳离子抗菌肽（CAMP）是一种含有12-50个残基的长肽，含有高含量的阳离子氨基酸，具有很强的活性，可以对抗包括致病菌、真菌和寄生虫在内的多种微生物。尽管进行了深入的研究和积累了丰富的详细信息，但它们的作用方式仍未得到很好的理解。MUC7 12-mer是一种从低分子量唾液粘蛋白7中提取的抗菌肽，本研究是MUC7 12-mer特性和作用机制研究的一部分。这种肽对机会性真菌病原体白色念珠菌和口腔致龋齿细菌变形链球菌具有有效的抗菌特性。我们最近采用了一种全球方法，可以同时研究抗菌肽的许多不同方面的作用。在这种方法中，同时检测了数千个酵母缺失突变体对肽的敏感性改变。在已确定的对该肽过敏的缺失中，许多涉及与RIM101信号通路相关的基因，该信号通路最著名的是对环境ph变化的反应。在第一个特异性目标中，我们将证实MUC7肽对该通路的诱导作用，并研究其在肽与靶细胞相互作用中的作用。在第二个目标中，我们将验证一个假设，提出MUC7肽存在两种不同的作用机制，一种是杀真菌的，另一种是抑真菌的，并将研究RIM101信号如何与两者相关。我们还将把这项研究扩展到致病性酵母白色念珠菌和钙信号，我们最近发现钙信号在防御MUC7肽中起作用，类似于酿酒酵母的RIM101反应。在第三个目标中，我们将通过直接选择对该肽具有抗性的酿酒酵母缺失突变体来扩展原始适应度分析。

DESCRIPTION (provided by applicant): Cationic antimicrobial peptides (CAMP), 12-50 residues long eptides with high content of cationic amino acids, are characterized by strong activities directed against broad range of microorganisms including pathogenic bacteria, fungi and parasites. Despite intensive research and wealth of accumulated detailed information, their modes of action are not well understood. This proposal is a part of the ongoing research on elucidation of properties and mechanisms of action of MUC7 12-mer, an antimicrobial peptide derived from the low molecular-weight salivary mucin 7. This peptide has potent antimicrobial properties against opportunistic fungal pathogen Candida albicans and cariogenic oral bacterium Streptococcus mutans. We have recently employed a global approach enabling study of many different aspects of action of antimicrobial peptides at once. In this approach altered susceptibilities to the peptide of thousands deletion mutants of yeast Saccharomyces cerevisiae were tested simultaneously. Among identified deletions conferring hypersensitivity to the peptide, many involved genes associated with the RIM101 signaling pathway, best known as a response to changes in environmental pH. In the first Specific Aim we will confirm induction of this pathway by the MUC7 peptide and investigate its role in interaction of the peptide with target cells. In the second Aim we will test a hypothesis proposing existence of two distinct mechanisms of action of the MUC7 peptide, one fungicidal and the other fungiststic, and will investigate how the RIM101 signaling relates to both. We will also expand this study to the pathogenic yeast C. albicans and calcium signaling, which we have recently identified as playing a role in defense against the MUC7 peptide, analogous to that of the RIM101 response in S. cerevisiae. In the third Aim we will extend the original fitness profiling by direct selection for S. cerevisiae deletion mutants resistant to the peptide. Public Health Relevance: Due to the declining rate of discovery of new antibiotics and antifungal agents, and spread of resistant strains of pathogens, there is urgent need for development of new classes of antimicrobial therapies. Antimicrobial peptides are a potential source of novel drugs. Results of recently completed yeast deletion screen with MUC7 peptide provide new directions for studying its mechanisms of action.