Coordinate regulation of competence and pneumocin production in S. pneumoniae

描述（由申请方提供）：肺炎链球菌（肺炎球菌）是一种重要的人类病原体，是细菌性脑膜炎、肺炎和中耳炎的最常见原因。虽然肺炎球菌可引起严重疾病，但它是正常鼻咽植物群的一部分。它吸收和整合外源DNA的能力使肺炎球菌能够通过提供遗传适应的资源来抵抗清除的尝试。基因组分析表明，该物种的特点是大量的遗传多样性，主要来自与其他链球菌的DNA重组。肺炎球菌中的感受态受群体感应系统调节，该系统由玉米系统控制，其驱动大量基因的产生，包括参与DNA摄取和重组的那些基因。有能力的肺炎球菌可以通过一种叫做“自相残杀”的机制溶解非有能力的群体成员，释放出他们的DNA。释放的DNA被感受态细胞吸收，可以作为新遗传物质的来源。参与自相残杀和自相残杀免疫的蛋白质在肺炎球菌和其他相关链球菌物种中高度保守，限制了裂解的目标群体为未能诱导感受态的群体成员。从blp基因座产生裂解性肺炎球菌细菌素（pneumococins）具有扩大DNA释放的靶范围的潜力。blp基因座是由一个平行的群体感应系统控制的。在blp基因座中的一些基因已被证明是上调在早期的感受态诱导，我们已经证明，刺激的感受态诱导肺素基因在一些分离株的转录。由于blp簇中编码的肺炎球菌素及其免疫蛋白在菌株之间是可变的，因此它们可以促进广泛的肺炎球菌和相关链球菌物种的裂解，而不依赖于靶标的感受态。我们假设，协调表达的mecins与感受态将增加潜在的目标生物体的DNA释放和摄取。在该提案的目标1中，我们将通过感受态诱导来研究肺炎菌素交叉刺激的机制。在目标2中，我们将确定调节蛋白CiaRH和HtrA在控制blp和com系统之间的串扰中的作用。在目标3中，我们将通过证明产肺炎菌素菌株在获得外源DNA方面优于仅依赖于杀兄弟的菌株来验证协调blp/com调节增加了DNA释放的靶范围。将在优化条件下体外研究DNA交换事件，并在小鼠鼻内定殖期间进行体内研究。尽管不断尝试从宿主和周围植物群中清除，但这种病原体的持续存在证明了基因组多样性和适应性的力量。了解表达的mammocins如何促进这种多样性，将使我们能够更好地预测，也许阻止通过遗传交换逃避控制措施的企图。

DESCRIPTION (provided by applicant): Streptococcus pneumoniae (pneumococcus) is an important human pathogen and the most common cause of bacterial meningitis, pneumonia and otitis media. Although it can cause significant disease, pneumococcus is part of the normal nasopharyngeal flora. Its ability to take up and incorporate foreign DNA has allowed pneumococcus to resist attempts at clearance by providing a resource for genetic adaptation. Genome analysis has demonstrated that this species is characterized by an enormous amount of genetic diversity largely derived from recombination with DNA from other streptococci. The competence state in pneumococcus is regulated by a quorum sensing system controlled by the com system which drives the production of a large number of genes including those involved in DNA uptake and recombination. Competent pneumococci can lyse non-competent members of the population releasing their DNA via a mechanism called fratricide. Released DNA is taken up by competent cells and can serve as a source of new genetic material. The proteins involved in fratricide and fratricide immunity are highly conserved among pneumococci and other related strep species limiting the target population for lysis to members of the population that have failed to induce competence. The production of lytic pneumococcal bacteriocins (pneumocins) from the blp locus has the potential to expand the target range for DNA release. The blp locus is controlled by a parallel quorum sensing system to that required for competence induction. A number of genes in the blp locus have been shown to be upregulated during early competence induction and we have demonstrated that stimulation of competence induces transcription of the pneumocin genes in some isolates. Because the pneumocins and their immunity proteins encoded in the blp cluster are variable from strain to strain, they can promote lysis of a wide range of pneumococci and related streptococcal species independent of the competence state of the target. We hypothesize that coordinate expression of pneumocins with the competence state will increase the potential target organisms for DNA release and uptake. In Aim1 of the proposal we will investigate the mechanism of cross stimulation of pneumocin by competence induction. In Aim 2 we will determine the role of the regulatory proteins CiaRH and HtrA in controlling the cross talk between the blp and com systems. In Aim3, we will verify that coordinate blp/com regulation increases the target range for DNA release by demonstrating that pneumocin producing strains have an advantage over strains that rely solely on fratricide in the acquisition of foreign DNA. DNA exchange events will be studied in vitro under optimized conditions and in vivo, during mouse nasal colonization. The persistence of this pathogen despite ongoing attempts at clearance from both the host and the surrounding flora is a testament to the power of genomic diversity and adaptation. Understanding how the variably expressed pneumocins contribute to this diversity will allow us to better anticipate and perhaps block attempts at escape from control measures via genetic exchange.