S. sanguis Adhesion: Molecular Basis of Specificity

在上一个资助期，血链球菌粘附于牙齿的生物学和机制与链球菌相比进行了建模。gordonii。通过我们开发的体内表达技术（1VET）库和唾液包被羟基磷灰石（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，我们发现β-葡萄糖苷代谢系统有助于体外和体内粘附和生物膜形成的全局控制。我们还鉴定和鉴定了S. gordonii，其似乎区分sHA生物膜模型中的固着、非固着和自由生长的细胞。这些基因和蛋白质 似乎包括附着力维护系统（AMS）。In S. sanguis和S. gordonii中，AMS被假设为基因和蛋白质的模块，其作为网络起作用以控制粘附和初始生物膜形成的特异性，从而解释了我们现在在S. gordonii和S.作为先驱的殖民者。为了检验我们的假设，AMS，包括bfrAB、srtA、sspA、sspB、scaA、abpB、msrA及其蛋白产物，调节粘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以转录调节SspB; (2)显示sspA和sspB以及其他粘附素的突变改变了表面原纤维的结构和功能; (3)描述包括AMS模块的网络的原理证明;以及 (4)比较AMS基因和蛋白在S. gordonii与S. sanguis。 总的来说，这些研究将把AMS描述为一个独特的生物网络，使先锋口腔链球菌能够竞争性地粘附和定植在牙齿上，并通过唾液吞咽来根除。

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.