COORDINATION OF S MUTANS SUCROSE METABOLISM

这是一个修改后的R29应用程序。变形链球菌致龋性 通过多种途径与蔗糖代谢相关，其中 一些制造糖聚合物用于殖民和能量储存， 另一些则产生导致蛀牙的酸。最近的研究表明 几种途径，ftf; gftBC和cytoA，是由蔗糖诱导的， Gtf A被果糖抑制，果糖是Gtf活性的产物。座椅位置记忆模块 操纵子在细胞内由果糖、G-1-P和G-6-P诱导， 各种途径的蔗糖代谢物。因此，假设S. 变形杆菌显示几种蔗糖途径的协调表达。的 协调表达可由蔗糖代谢物介导，例如 果糖或G-1 -P，其可以从一个途径产生，并且交叉- 规范另一个。当糖不可用时，多糖降解 响应于糖饥饿可以诱导途径释放游离的 糖，这反过来又可能交叉调节其他途径。 迄今为止，研究了13条蔗糖代谢途径。变种人已经被确认了 其中，九个主要途径已被遗传研究：这些是 gtfB、gtfC、gtfD、ftf; dexA、fru、msm、glg;其余四种 是海藻糖、葡萄糖和果糖PTS途径， 降解途径因为九种主要的基因和突变体 通路是可用的，我们可以开始立即测试这个假设。 我们建议：（1）确定其他途径对msm的交叉调节， dexA或fruA，其可以通过显色化学品直接监测， 使用同基因突变体。(2)识别其他途径的交叉调节 对ftf、gtfBC、cDNAA和glg的影响，这些物质没有容易分析的 表型，使用其中一种途径与报告基因融合的菌株 一个是基因，另一个是失活的。(3)评估交叉调节 同时在多个路径中。(4)识别诱导 多糖降解途径对糖饥饿的反应。的 这些结果将有助于我们了解S.变形 蔗糖代谢是S.变形菌毒力

This is a revised R29 application. Streptococcus mutans cariogenicity is associated with its sucrose metabolism via multiple pathways, among which some make sugar polymers for colonization and energy storage, while others produce acid that causes tooth decay. Recent studies have shown that several pathways, ftf; gftBC and scrA, are induced by sucrose, while scrA is repressed by fructose, a product of the Gtf activity. The msm operon is induced intracellularly by fructose, G-1-P and G-6-P, which are sucrose metabolites of various pathways. It is thus hypothesized that S. mutans shows coordinated expression of several sucrose pathways. The coordinated expression may be mediated by sucrose metabolites, such as fructose or G-1 -P, which may be generated from one pathway and cross- regulate another. When sugar is unavailable, polysaccharide-degradation pathways may be induced in response to sugar starvation to release free sugars, which in turn may cross-regulate other pathways. To date, 13 sucrose metabolic pathways of S. mutans have been identified. Among them, nine major pathways have been genetically studied: these are gtfB, gtfC, gtfD, ftf; dexA, fru, scrAB, msm and glg; the remaining four are the trehalose, glucose and fructose PTS pathways and the glycogen degradation pathway. Since the genes and mutants of the nine major pathways are available, we can begin testing this hypothesis immediately. We propose to: (1) Identify cross-regulation of other pathways on msm, dexA or fruA, which can be monitored directly by chromogenic chemicals, using isogeneic mutants. (2) Identify cross-regulation of other pathways on ftf, gtfBC, scrA and glg, which do not have a readily assayable phenotype, using strains in which one pathway is fused with a reporter gene and the other is inactivated. (3) Evaluate cross-regulation simultaneously among multiple pathways. (4) Identify induction of polysaccharidedegradation pathways in response to sugar starvation. The results will help us understand the genetic regulation of S. mutans sucrose metabolism, which is critical for S. mutans virulence.