Glycosylation & Function of an Oral Streptococcal Adhesin

口腔链球菌启动了最复杂的人类生物膜--牙菌斑的形成；它们有 也被确定为细菌性心内膜炎的重要病原体。牙菌斑和牙菌斑的形成 植被是生物被膜形成的过程，生物被膜的形成能力对细菌的毒力至关重要。我们 从口腔细菌副链球菌体内鉴定出富含丝氨酸的糖蛋白FAPL 证明了FAPL是生物被膜形成和细菌在体内定植所必需的。糖基化 FAPL对成熟生物膜的发育具有重要意义。富含丝氨酸的FAPL糖蛋白也存在于 许多致病链球菌和葡萄球菌，对细菌的毒力至关重要。到目前为止，人们对此知之甚少 关于富含丝氨酸的糖蛋白的生物发生。我们和其他人已经确定了一个基因簇，它需要 富含丝氨酸的蛋白质的生物发生。我们的研究已经证明副血链球菌调节它的能力 利用专门的FAPL糖基化系统形成生物膜。我们假设FAPL糖基化 而生物发生是一个分两步走的过程。最初的糖基化步骤是由一种双组分酶控制的 复杂；随后的糖基化步骤取决于糖基转移酶和 附件安全组件。在特定的目标#1中，我们将测试辅助蛋白功能的假设 作为分子伴侣调节糖基转移酶在双组分体系中的活性 启动稳定的功能性粘附素的生产。在具体目标2中，我们将确定相互作用 糖基转移酶和SEC的一个辅助成分之间的关系来测试我们的假设 分泌在第二步是偶联的。此外，我们将确定蛋白质-蛋白质相互作用域 对FAPL糖基化和细菌生物膜的形成和定植很重要。我们预计 这项工作的完成将有助于更好地理解FAPL糖基化和生物发生以及它们的 细菌生物膜形成和定植中的生物学作用。因为富含丝氨酸的蛋白质在 许多链球菌和葡萄球菌的病原体，FAPL生物合成途径的特征将提供 对富含丝氨酸蛋白质的糖基化和生物发生的共同主题的见解。关于这一新的信息 生物膜形成所需的相互作用域可能导致治疗剂的设计 干扰富含丝氨酸的糖蛋白的作用并提出预防和治疗细菌的新方法 感染。

Oral streptococci initiate the formation of the most complex human biofilms, dental plaque; they have also been identified as important pathogens for bacterial endocarditis. Development of dental plaque and vegetation is a biofilm formation process, the ability to form biofilm is critical for bacterial virulence. We have identified a serine-rich glycoprotein Fapl from an oral bacterium, Streptococcusparasanguis and demonstrated that Fapl is required for biofilm formation and bacterial colonization in vivo. Glycosylation of Fapl is important for development of mature biofilm. Fapl-like serine-rich glycoproteins are also found in many pathogenic streptococci and staphylococci and critical for bacterial virulence. To date, little is known about biogenesis of serine-rich glycoproteins. We and others have identified a gene cluster required for biogenesis of serine-rich proteins. Our studies have demonstrated that S.parasanguis modulates its ability to form biofilm by utilizing a specialized Fapl glycosylation system. We hypothesize that Fapl glycosylation and biogenesis is a two-step process. The initial glycosylation step is controlled by a two-component enzyme complex; the subsequent glycosylation step depends on the interaction between a glycosyltransferase and an accessory Sec component. In specific aim #1, we will test the hypothesis that an accessory protein functions as a molecular chaperone to modulate the activity of a glycosyltransferase in the two-component system that initiates the production of a stable functional adhesin. In specific aim #2, we will determine interactions between glycosyltransferase and an accessory Sec component to test our hypothesis that glycosylationand secretion is coupled in the second step. In addition, we will identify protein-protein interaction domains that are important for Fapl glycosylation and bacterial biofilm formation and colonization. We expect completion of this work will lead to a better understanding of Fapl glycosylation and biogenesis and their biological function in bacterial biofilm formation and colonization. As serine-rich proteins are conserved in many streptococcal and staphylococcal pathogens, characterization of Fapl biosynthetic pathway will provide insights on a common theme in glycosylation and biogenesis of serine-rich proteins. This new information on interaction domains required for biofilm formation may lead to the design of therapeutic agent that can disrupt the action of serine-rich glycoproteins and suggest new approaches to prevent and treat bacterial infection.