GENETICS OF INTEGRATION HOST FACTOR GENES FROM S MUTANS

变形链球菌是一种引起龋齿的病原体。它的能力 造成的损害与长链的产生有着很强的联系 葡萄糖聚合物（葡聚糖），其允许细菌成功 在牙齿的光滑表面定居。为了合成这些葡聚糖， 细菌拥有一个基因家族，该家族表达称为 葡糖基转移酶。葡萄糖基转移酶基因，gtfB， gtfC和gtfD受到强烈调控。本项目的长期目标 是鉴定调控其表达的元件，然后 随后对其进行表征。鉴定的第一个调节剂是 全局原核调节因子，整合宿主因子（IHF）。IHF网 其作用是抑制克隆S.突变gtf基因高达6倍 在大肠杆菌中表达线圈。 IHF与几乎所有形式的类核密切相关 操作，即复制、重组和基因表达。在大肠 螺旋体和其他革兰氏阴性菌，IHF可以影响基因表达 通过其结合DNA的能力进行转录调控 在其同源结合位点。在正式分析IHF功能之前， 可以进行GTF表达。有必要证明 在E. coli中与S.变异人因此 第一步是建立S.变异体 这将包括克隆和测序的IHF基因 以在S.变异人 尚未对任何革兰氏阳性菌属的IHF进行表征。一旦 编码IHF的基因已经被克隆，一组初步的 将进行互补实验以比较E. coli和革兰氏阳性菌S. 直接致突变IHF。最后是S.构建的变异株 可以评估IHF缺陷以确定其表达 它们的gtf基因相对于野生型S.变异人

Streptococcus mutans is a causative agent of dental caries. It's ability to inflict damage is strongly linked to the production of long chain glucose polymers (glucans) which allow the bacteria to successfully colonize the smooth surface of teeth. To synthesize these glucans the bacteria possesses a family of genes that express enzymes called glucosyltransferases. Expression of the glucosyltransferase genes, gtfB, gtfC and gtfD are strongly regulated. The long term goal of this project is to identify elements that regulate their expression and then to subsequently characterize them. The first modulator identified was the global prokaryotic regulator, Integration Host Factor (IHF). IHF's net effect is to repress cloned S. mutans gtf genes as much as 6 fold when expressed in E. coil. IHF is intimately involved in virtually all forms of nucleoid manipulation i.e. replication, recombination and gene expression. In E. coil and other gram negative bacteria, IHF can affect gene expression through either transcriptional regulation through its ability to bind DNA at its cognate binding site. Before a formal analysis of IHF function of gtf expression can be undertaken it will be necessary to demonstrate that the phenotypes observed in E. coli are similar in S. mutans. Thus the first step is to establish the genetics of IHF homologs in S. mutans. This will include the cloning and sequencing of the IHF genes in addition to constructing IHF mutans in S. mutans. No IHF from any gram positive genera has yet been characterized. Once the genes that code for IHF have been cloned, a preliminary set of complementation experiments will be performed to compare E. coli and S. mutans IHF directly. Finally the S. mutans strain constructed to be deficient in IHF can be assessed to determine their ability to express their gtf genes relative to wild type S. mutans.