S. sanguis Adhesion: Molecular Basis of Specificity

在之前的赠款期间，我们模拟了血链球菌与戈登链球菌的牙齿黏附的生物学和机制。通过我们开发的体内表达技术(1VET)文库和唾液包裹的羟基磷灰石(SHA)的早期生物膜模型，报告基因和突变方法，以及基因表达的直接检测，我们证明了甜菜糖苷代谢系统在体外和体内对黏附和生物膜形成的全面控制。我们还鉴定和表征了戈登链球菌的粘附素基因和蛋白，它们似乎区分了沙氏生物膜模型中的固位细胞、浮游细胞和自由生长细胞。这些基因和蛋白质 似乎包括一个粘合维护系统(AMS)。在血链球菌和血链球菌中，AMS被假设为一个基因和蛋白质模块，其功能是作为一个网络来控制黏附和初始生物膜形成的特异性，解释了我们现在作为先驱定殖者在血链球菌和血链球菌中表现出的竞争差异。为了验证我们的假设，即AMS，包括bfrAB、srtA、SSPA、sspB、SCAA、abpB、MSRA及其蛋白产物，调节黏附和初始生物膜形成的特异性，我们将： (1)确定srtA如何作用于sspA转录调控sspB； (2)SSPA和SSPB等粘附素基因突变改变了表面纤维的结构和功能； (3)描述由AMS模块组成的网络的原理证明；以及 (4)比较AMS基因和蛋白在戈尔登链霉菌和血链球菌中的表达和功能。 总的来说，这些研究将把AMS描述为一个独特的生物网络，使先驱口腔链球菌能够竞争性地附着和定植牙齿，并通过吞咽唾液来抵御根除。

During the previous grant period, the biology and mechanisms of adhesion to teeth by Streptococcus sanguis were modeled in comparison to S. gordonii. Facilitated by our development of an In Vivo Expression Technology (1VET) library and an early biofilm model on saliva-coated hydroxyapatite (sHA), reporter gene and mutational approaches, and direct detection of gene expression, we showed that betaglucoside metabolism systems contribute to the global control of adhesion and biofilm formation in vitro and in vivo. We also identified and characterized adhesin genes and proteins of S. gordonii that appear to distinguish sessile, planktonic and free-growing cells in an sHA biofilm model. These genes and proteins appear to comprise an Adhesion Maintenance System (AMS). In S. sanguis and S. gordonii, the AMS is hypothesized to be a module of genes and proteins that function as a network to control the specificity of adhesion and initial biofilm formation, explaining competitive differences we now show in S. gordonii and S. sanguis as pioneer colonizers. To test our hypothesis that the AMS, including bfrAB, srtA, sspA, sspB, scaA, abpB, msrA and their protein products, regulates the specificity of adhesion and initial biofilm formation, we will: (1) determine how SrtA acts on SspA to transcriptionally regulate sspB; (2) show that mutations in sspA and sspB and other adhesins modify the structure and function of surface fibrils; (3) describe the proof-of-principle of a network that comprises the AMS module; and (4) compare the expression and function of AMS genes and proteins in S. gordonii with S. sanguis. Collectively, these studies will characterize the AMS as a unique biological network that enables the pioneer oral streptococci to competitively adhere and colonize the teeth and withstand eradication by swallowing in saliva.