Biosynthesis, structure and function of cell wall in Streptococcus mutans

乳杆菌目的许多种的细胞壁由多个肽聚糖层组成 修饰有以存在以下物质为特征的特定类型的多糖 鼠李糖。变形链球菌是人类龋病的重要病原体， 也与菌血症和感染性心内膜炎有关。根据化学结构 的碳水化合物，S。变形杆菌分为血清型C、E、F和K， 在口腔中发现的大约70-80%的菌株被归类为血清型C。血清型 C-特异性碳水化合物（SCC）。变形链球菌由多聚鼠李糖主链和α- 连接的葡萄糖侧链。虽然碳水化合物的结构已被报道为所有 S.变形链球菌血清型，我们最近对这些糖聚合物结构的了解表明， 功能上重要的修饰，甘油磷酸，被忽略了，可能是由于它的 纯化步骤中的损失。这一新发现证明了对这种化学物质进行重新检查的合理性。 特定类型碳水化合物的结构。拟议研究的目标之一是 确定了从S.变异人使用温和的、非破坏性的 方法.此外，很少有人知道的多酶过程中涉及的附件， 葡萄糖侧链到SCC的多聚鼠李糖主链和甘油的功能 S.变异人我们的初步发现表明甘油 磷酸修饰在S.变形菌形态，自溶，耐药性 抗菌剂和生物膜形成。我们建议识别和功能特性的 酶参与葡萄糖侧链连接到多聚鼠李糖，并研究 甘油磷酸酯修饰的分子机制， 形态、自溶和生物膜形成。为了实现我们的目标，我们将 链球菌遗传学，体外酶学，多糖的NMR光谱，分析 磷脂的化学、质谱分析和各种显微镜方法 包括基于AFM的纳米力学。细胞壁的生物合成机制是一个历史性的 开发新型抗菌剂的首选目标。为了验证 以磷酸甘油装饰SCC作为潜在的药物靶点，我们将确定其作用 在大鼠龋齿模型中的这种修饰。成功的结果将指导未来的细胞壁研究 在其他重要的革兰氏阳性菌的生物发生和新的战略， 处理S.变形杆菌感染

The cell wall of many species of Lactobacillales consists of multiple peptidoglycan layers decorated with serotype-specific polysaccharides that are characterized by the presence of rhamnose. Streptococcus mutans is a key etiological agent of human dental caries, and has also been implicated in bacteremia and infective endocarditis. Based on the chemical structures of serotype-specific carbohydrates, S. mutans is classified into serotypes c, e, f and k with approximately 70-80% of strains found in the oral cavity classified as serotype c. The serotype c-specific carbohydrate (SCC) of S. mutans is composed of a polyrhamnose backbone with α- linked glucose side-chains. Although carbohydrate structures have been reported for all S. mutans serotypes, our recent insights into the structure of these glycopolymers indicate that the functionally important modification, glycerol phosphate, was overlooked, possibly due to its loss during the purification steps. This new finding justifies a re-examination of the chemical structures of serotype-specific carbohydrates. One of the goals of the proposed study is to determine the molecular structure of SCC isolated from S. mutans using mild, non-destructive methods. Moreover, little is known about the multienzyme processes involved in attachment of the glucose side-chains to the polyrhamnose backbone of SCC and the function of the glycerol phosphate modification in S. mutans. Our preliminary findings revealed that the glycerol phosphate modification plays important roles in S. mutans morphology, autolysis, resistance to antimicrobials and biofilm formation. We propose to identify and functionally characterize the enzymes involved in glucose side-chain attachment to polyrhamnose, and investigate the molecular mechanisms underlying the functions of glycerol phosphate modification in morphology, autolysis and biofilm formation. To accomplish our goals, we will employ streptococcal genetics, in vitro enzymology, NMR spectroscopy of polysaccharides, analytical chemistry, mass spectrometric analysis of phospholipids, and various methods of microscopy including AFM-based nanomechanics. The cell wall biosynthetic machinery is an historically preferred target for the development of novel antimicrobials. In order to validate the pathway of SCC decoration with glycerol phosphate as a potential drug target, we will determine the role of this modification in a rat caries model. Successful outcomes will guide future studies of cell wall biogenesis in other important Gram-positive bacteria and the development of novel strategies to treat S. mutans infections.