Characterization of a novel S. aureus biofilm polysaccharide

总结 金黄色葡萄球菌是一种重要的人类病原体，可引起多种疾病，其中一些疾病 目前的治疗方法主要局限于抗生素治疗。然而，S. 金黄色葡萄球菌能够在植入物或组织上形成生物膜，使细菌对抗生素具有抗性， 宿主免疫防御系统而不获得遗传抗性性状。因此，生物膜形成通常导致 治疗失败。生物膜是由多层细菌细胞组成的细菌群落， 将细菌保持在生物膜结构内的细胞外基质。迄今为止，葡萄球菌生物膜基质 已显示由多糖、蛋白质和细胞外DNA组成，但其组成尚未确定。 完全定义。因此，了解生物膜基质组成对于揭示生物膜形成机制至关重要 并为治疗或诊断开发提供潜在的靶点。不同的生物膜基质蛋白具有 已经报道，但只有非常少的种类的基质多糖已被确定。我们已经证明 突变在以前未知的推定的多糖合成基因的基因簇中的S. 金黄色葡萄球菌基因组减少生物膜形成。这些结果表明，基因簇参与了 生产一种新的多糖，它有助于S.金黄色葡萄球菌毒力通过促进生物膜形成。 因此，本申请的目的是验证和研究这种新型多糖。为此，我们将在分子水平上 对Aim 1中的基因簇进行了表征，并对Aim 1中的新多糖进行了生化鉴定， 目的2中，该多糖在生物膜形成和植入骨感染模型中的毒力。

Summary Staphylocuccus aureus is a significant human pathogen that causes a wide range of diseases, some of which are serious and difficult to treat. Current treatment methods are largely limited to antibiotic therapy. However, S. aureus is capable of forming biofilm on implants or tissues rendering the bacteria resistance to antibiotics and to host immune defense system without acqiuring genetic resistance traits. Thus, biofilm formation often leads to treament failures. Biofilms are bacterial communities consist of multiple layers of bacterial cells encased within an extracellular matrix that keeps the bacteria within the biofilm structure. To date, staphylococcal biofilm matrix has been shown to consist of polysaccharides, proteins and extracellular DNA but the composition is not been fully defined. Understanding biofilm matrix composition is therefore critical to unveil biofilm formaiton mechanism and provide potential targets for therapeutic or diagnostic development. Diverse biofilm matrix proteins have been reported but only very few species of matrix polysaccharide have been identified. We have shown that mutations in an previously uncharacterized gene cluster of putative polysaccharide sythesis genes in the S. aureus genome reduced biofilm formation. These results indicate that the gene cluster is involved in the production of a novel polysaccharide, which contributes to S. aureus virulence by promoting biofilm formation. Thus, the goal of this application is to verify and study this novel polysaccharide. To this end, we will molecularly characterize the gene cluster and biochemically identify the novel polysaccharide in Aim 1 and study the role of this polysacharide in biofilm formation and in virulence in an implant bone infection model in Aim 2.