REGULATION OF STREPTOCOCCUS GORDONII GLUCOSYLTRANSFERASE

戈登链球菌葡萄糖基转移酶的调控

• 批准号: 6126963
• 负责人: M Margaret VICKERMAN
• 金额: $ 24.73万
• 依托单位: INDIANA UNIV-PURDUE UNIV AT INDIANAPOLIS
• 依托单位国家: 美国
• 财政年份: 1995
• 资助国家: 美国
• 起止时间: 1995-09-30 至 2005-07-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6126963
• 关键词: DNA footprinting; Enterococcus; Streptococcus; Streptococcus sanguis; bacterial genetics; beta galactosidase; binding sites; chloramphenicol acetyltransferase; enzyme activity; fusion gene; gel mobility shift assay; gene environment interaction; gene expression; gene mutation; genetic operator element; genetic promoter element; genetic regulation; genetic strain; hexosyltransferase; oral bacteria; polymerase chain reaction; regulatory gene; reporter genes; structural genes

Early colonizing dental plaque bacteria such as Streptococcus gordonii, form the substratum to which later-colonizing microbial species, including potential pathogens, attach in the process of mature plaque development. The S. gordonii single glucosyltransferase (GTF) enzyme hydrolyzes sucrose to form glucan polymers that can facilitate bacterial accumulation on surfaces. The level of GTF activity affects the ability of S. gordonii cells to colonize surfaces in vitro and therefore, may affect their ability to establish in ecological niches in vivo. Environmental and growth conditions are known to affect S. gordonii GTF activity. Expression of the GTF structural gene, gtfG, is positively regulated by the upstream determinant, rgg. S. gordonii undergo a reversible phase variation between high and low levels of GTF activity. Although the molecular basis for GTF phase variation is not known, nucleotide changes or rearrangements in rgg or gtfG are not necessary; thus distally- located DNA is implicated in the control of gtfG expression. The working hypothesis of the proposed studies is that regulation of GTF activity in S. gordonii involves complex molecular interactions that may have ecological implications for survival of S. gordonii in the oral cavity. The goal of the proposed studies, to identify environmental signals and genetic elements involved in control of S. gordonii GTF activity, will be pursued in four specific aims: 1) to characterize the molecular mechanism of rgg regulation of gtfG through structural and genetic studies; 2) to use reporter genes fusions to identify distally-located S. gordonii genes that affect rgg and gtfG expression; 3) to identify environmental conditions that affect expression of gtfG and its regulatory gene(s); 4) to use random arbitrarily primed PCR to identify additional S. gordonii genes that show altered levels of expression in response to genetic or environmental factors that affect GTF activity. It is hoped that these studies will provide an understanding of the molecular interactions and conditions that favor or disfavor glucan production by the commensal organism S. gordonii. In the long term, such information may provide insights into factors which control, and possibly select for, a healthy oral flora and potentially be implemented in the development of biologically based therapeutic regimens.

早期定植的牙菌斑细菌如戈登链球菌形成了基质，在成熟牙菌斑发育过程中，后期定植的微生物物种（包括潜在的病原体）附着在该基质上。 色葡萄戈登氏单葡糖基转移酶（GTF）水解蔗糖以形成葡聚糖聚合物，该葡聚糖聚合物可以促进细菌在表面上的积累。 GTF活性的高低影响S. Gordonii细胞在体外定殖于表面，因此可能影响它们在体内建立生态小生境的能力。已知环境和生长条件影响S.戈登氏菌GTF活性。 GTF结构基因gtfG的表达受上游决定子rgg的正调控。S.戈登氏菌在高水平和低水平GTF活性之间经历可逆的相位变化。 尽管GTF相位变异的分子基础未知，但rgg或gtfG中的核苷酸变化或重排不是必需的;因此，远端定位的DNA涉及gtfG表达的控制。本研究的工作假设是S. gordonii涉及复杂的分子相互作用，可能对S.口腔中的戈登氏菌 本研究的目的是确定环境信号和参与控制S。gordonii GTF活性，将在四个具体目标中进行：1）通过结构和遗传研究表征gtfG的rgg调节的分子机制; 2）使用报告基因融合来鉴定远端定位的S. gordonii影响rgg和gtfG表达的基因; 3）鉴定影响gtfG及其调控基因表达的环境条件; 4）使用随机引物PCR鉴定另外的S. gordonii基因，其响应于影响GTF活性的遗传或环境因素而显示改变的表达水平。 希望这些研究能帮助我们了解分子间的相互作用和有利于或不利于葡聚糖生产的条件。gordonii。 从长远来看，这些信息可以提供对控制和可能选择健康口腔植物群的因素的了解，并可能在基于生物学的治疗方案的开发中实施。