SRF OPERON--REGULATION AND ROLE IN GENETIC COMPETENCE

描述(改编自调查人员的摘要)：细菌拥有 感知环境和新陈代谢状况的监管网络，以及 通过产生和传递影响基因表达的信号来做出反应。 饥饿和高细胞密度影响毒力因子的产生 如毒素、抗生素和降解酶等 网络。它们还诱导复杂的细胞分化过程，使 升至抗性细胞类型或可获得外源DNA的能力细胞。 在枯草芽孢杆菌中，SRF操纵子驻留在一个调节网络中，该网络 控制营养耗竭和高细胞密度引起的过程。SRF 编码表面素合酶，一种抗生素生物合成操纵子，和coms，a 控制能力发展的调节肽。这次会议的主要目标是 项目是了解SRF和COMS是如何监管的，以及COMS如何刺激 能力发展。SRF由两个趋同的监管机构控制 小路。一种是仲裁群体感应控制，涉及两个组件 调节因子COMP和COMP；磷酸化COMP激活SRF转录。这个 另一种途径，涉及Phr胞外肽和SPOCK 寡肽渗透酶，被饥饿和高细胞密度激活； 通过Shok导入的PhR肽抑制Rap磷酸酶转换 昏迷变成一种不活跃的形式，允许两种途径之间的相互作用。 Phr表达的激活需要RNA聚合酶的SigmaH形式，即 其活性是由饥饿诱导的，需要依赖于ATP的ClpX 监护人。ClpX在激活E-SigmaH中的作用将由以下因素决定 体外转录用RNA聚合酶的纯化与重组 含有纯化的ClpX蛋白的反应。基因突变抑制了 ClpX突变体的表型将被表征以确定因素 影响依赖ClpX的E-SigmaH的激活。ClpX在中的其他功能 SRF转录的激活将通过测试效果来确定 ClpX comp和clpX spok双突变体对SRF表达的影响。需要COMS 为了释放ComK，能力基因表达的转录激活因子， 从能力抑制蛋白MecA和ClpC中分离得到。依赖通讯的人 释放被认为可以将ComK从受调控的蛋白质降解中拯救出来。一系列 将对COMS点突变进行分析，以确定COMS在 激活能力基因的表达。这些研究将进一步 了解应激诱导蛋白和细胞外信号转导通路之间的功能联系 原核细胞分化的调控。

DESCRIPTION (adapted from the investigator's abstract): Bacteria possess regulatory networks that sense environmental and metabolic conditions, and respond by generating and transducing signals that affect gene expression. Starvation and high cell density influence the production of virulence factors such as toxins, antibiotics, and degradative enzymes through regulatory networks. They also induce complex cell differentiation processes that give rise to resistant cell types or competent cells that can acquire exogenous DNA. In Bacillus subtilis, the srf operon resides within a regulatory network that governs processes induced by nutrient depletion and high cell density. srf encodes surfactin synthetase, an antibiotic biosynthesis operon, and ComS, a regulatory peptide that controls competence development. The major goal of the project is to understand how srf and comS are regulated and how ComS stimulates competence development. srf is under the control of two converging regulatory pathways. One mediates quorum-sensing control and involves the two-component regulators ComP and ComA; phorphorylated ComA activates srf transcription. The other pathway, involving the Phr extracellular peptide and the SpoOK oligopeptide permease, is activated by starvation and high cell density; the Phr peptide, imported via SpoOK, inhibits the Rap phosphatase that converts ComA to an inactive form, allowing interplay between the two pathways. Activation of phr expression requires the SigmaH form of RNA polymerase, the activity of which is induced by starvation and requires ClpX, an ATP-dependent chaperone. The role of ClpX in the activation of E-SigmaH will be determined by purification and reconstitution of RNA polymerase in vitro for transcription reactions containing purified ClpX proteins. Mutations which suppress the phenotype of a clpX mutant will be characterized to identify factors influencing ClpX-dependent activation of E-SigmaH. Other functions of ClpX in the activation of srf transcription will be identified by testing the effects of clpX comP and clpX spoOK double mutants on srf expression. ComS is required to release ComK, the transcriptional activator of competence gene expression, from the competence inhibitory proteins MecA and ClpC. The ComS-dependent release is thought to rescue ComK from regulated proteolysis. A collection of ComS point mutations will be analyzed to determine the function of ComS in the activation of competence gene expression. These studies will further understanding of the functional links between stress-induced proteins and the regulation of prokaryotic cellular differentiation.