Salivary Amylase: Role in Dental Caries Pathogenesis

描述：唾液淀粉酶提供了唾液蛋白的一个极好的例子，它具有调节口腔细菌定植的潜力。虽然它在溶液中与细菌结合可能导致细菌清除（保护），但它在牙釉质膜上的存在可能促进牙菌斑的形成（有害）。在上一期研究中，我们研究了淀粉酶在淀粉水解、羟基磷灰石结合和菌斑形成过程中所起的生理作用。我们将继续通过分子方法对淀粉酶的三种功能进行研究。将设计几种淀粉酶突变体，以消除淀粉的结合和水解，淀粉酶与羟基磷灰石和S. gordonii蛋白AbpA的结合。这些突变体将使用已建立的杆状病毒表达系统产生。这些突变体将分别用于说明这三种功能之间的相互关系，并测试与淀粉酶中淀粉结合、HAp结合和细菌结合位点定位有关的假设。

DESCRIPTION: Salivary amylase provides an excellent example of a salivary protein that has the potential to modulate the bacterial colonization in the oral cavity. Although its binding to bacteria in solution may result in bacterial clearance (protective) its presence in the enamel pellicle may facilitate Dental plaque formation (harmful). In the last granting period, the structure-function relationships of amylase were examined in the context of its physiological role in starch hydrolysis, hydroxyapatite binding and bacterial binding on plaque formation. We will continue our studies on the three functions of amylase through molecular approaches. Several mutants of amylase will be designed to abolish starch binding and hydrolysis, amylase binding to hydroxyapatite and S. gordonii protein AbpA. These mutants will be generated using an established baculovirus expression system. Individually, these mutants will be utilized to illustrate the interrelationships among the three functions and to test hypotheses related to the localization of starch binding, HAp binding and bacterial binding sites in amylase. In addition, using these mutants, we plan to study the role of amylase in the basic mechanisms responsible for the colonization of a pioneer bacterium S. gordonii and a cariogenic bacterium such as S. mutans. Given its stature as a major protein in human saliva and its ability to interact with proteins from S. gordonii (AbpA) and S. mutans (Gtf), amylase may play a central role in the enamel pellicle. Through amylase, S. mutans may bind to an established S. gordonii biofilm either directly or through an interaction with A. naeslundii: Our goal is to define the role of amylase in these complex intergeneric interactions. A well established flow cell model incorporating co-cultured S. gordonii, A. naeslundii and S. mutans bathed in amylase or saliva will be used to examine these relationships. The second generation amylase mutants proposed here will eventually lead to the design of strategies to manipulate human salivary amylase-bacterial interactions that favor the host and thus reduce the potential for Dental diseases mediated by biofilms. Finally, we are excited that our approach in dissecting the contribution of amylase to foster the colonization of S. mutans may serve as a model to study the role of other salivary proteins in the oral cavity.