Regulation of gtf Gene Expression in S mutans

变形链球菌中 gtf 基因表达的调控

• 批准号: 6606148
• 负责人: STEVEN D GOODMAN
• 金额: $ 26.45万
• 依托单位: UNIVERSITY OF SOUTHERN CALIFORNIA
• 依托单位国家: 美国
• 财政年份: 2001
• 资助国家: 美国
• 起止时间: 2001-08-01 至 2006-06-30
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/6606148
• 关键词: Streptococcus mutans; bacteria infection mechanism; bacterial genetics; dental agent; dental caries; gene deletion mutation; gene expression; genetic promoter element; genetic regulation; genetic regulatory element; genetic transcription; glucans; hexosyltransferase; messenger RNA; northern blottings; phenotype; plasmids; polymerase chain reaction; regulatory gene; reporter genes; transposon /insertion element

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) derived from dietary sucrose which allow the bacteria possesses a family of genes that express enzymes called glucosyltransferases (GTF). There are three GTFs in S. mutans. They share 50 percent sequence identity and are encoded by the homologous gtfB, gtfC and gtfD genes. The gtfB and gtfC gene are found in direct repeat with a mere 198 base paries separation between coding sequences. Although mutations in either gtfB or gtfC produce a colonizing deficient phenotype, little is known about their regulation. Until recently, the only effector known to regulate these genes was sucrose, the substrate of the GTFs. Supplemented sucrose transiently induces a 3-fold increase in a gtfB transcriptional fusion. Now we have demonstrated that both gtfB and gtfC show coordinated growth phase- dependent expression. For both genes, expression peaks prior to exponential growth and falls over 100-fold by early stationary phase. In this proposal, we intend to further study this phenomenon including identifying critical cis and trans acting elements and through mutagenesis determine how these elements affect gtf gene expression. Since these gtf genes are involved in the colonization process, the genetic elements that are found here will need to be examined in terms of the bacteria's pathogenic mechanisms.

链球菌突变是龋齿的病因。 它的造成损害的能力与源自饮食中蔗糖的长链葡萄糖聚合物（葡萄糖）的产生密切相关，这些脱饮食使细菌具有表达称为葡萄糖基转移酶（GTF）的基因家族。 S. mutans中有三个GTF。 它们具有50％的序列身份，并由同源GTFB，GTFC和GTFD基因编码。 直接重复发现GTFB和GTFC基因，仅在编码序列之间进行198个基本围栏分离。尽管GTFB或GTFC中的突变产生了定殖的缺陷表型，但对它们的调节知之甚少。 直到最近，已知调节这些基因的唯一效应子是GTF的底物蔗糖。补充蔗糖会瞬时诱导GTFB转录融合的3倍增加。 现在，我们已经证明了GTFB和GTFC均显示出协调的生长阶段与表达。 对于这两个基因，表达在指数生长之前峰值峰值，到早期固定期的100倍以上。 在此提案中，我们打算进一步研究这种现象，包括识别关键的顺式和反式作用元件，并通过诱变决定这些元素如何影响GTF基因表达。 由于这些GTF基因参与定殖过程，因此需要根据细菌的致病机制来检查此处发现的遗传因素。