Regulation in Fusobacterium-mediated coaggregation

项目总结 牙菌斑和相关的牙周疾病是一种常见的传染病，几乎 一半的美国成年人(CDC)。复杂的种内和种间相互作用调节着 多物种口腔微生物群落称为牙菌斑。牙菌斑是由一个有组织的， 高度复杂的微生物群落和革兰氏阴性厌氧菌核杆菌是一种关键的微生物 这种微生物群凭借其独特的能力与许多早期和晚期的殖民者进行物理聚集。 除了在牙周炎中的作用外，核杆菌还与几种口腔外疾病有关，包括早产。 出生和结直肠癌。尽管梭菌与其他细菌的相互作用已经广泛存在 研究并确定了四种共聚集粘附素，对其调节机制知之甚少 梭杆菌介导的共聚集，主要是由于缺乏强大的遗传工具箱来操纵F. 核糖体。为了克服这一点，我们最近开发了一种方便的核盘藻基因缺失系统，并 产生了一个庞大的随机转座子突变体文库，基因组覆盖率约为10倍。对这一点的筛选 LIBRARY发现了几种共聚集因子，其中包括一种名为CARS的独特的双组分系统- CARR和一个九基因操纵子，编码赖氨酸降解途径(LDP)，控制数量和 RADD活性。RADD是一种IV型自身转运蛋白，是一种多功能的粘附素，它能介导 梭菌与许多早期定殖者和一些晚期定殖者的粘附性。基于这些发现，我们计划 深入描述这两个监管因素。我们将第一次展示两种口腔细菌 组分信号组件以细胞密度依赖的方式调节细胞-细胞粘附素的表达 并鉴定了一种与细菌中赖氨酸分解代谢有关的赖氨酸核糖开关。在成功完成 这项研究，我们希望对理解多功能粘附素是如何 RADD是通过识别和破译相关的因素和机制来调节的。因为RADD需要F. 并入由最初的共生殖民者组成的已建立的群落，如 链球菌和放线菌，我们的发现将对理解 梭杆菌介导的共聚集在牙菌斑形成中的作用，将为研究牙菌斑的形成提供新的见解 针对这种重要病原体开发有效的治疗策略。

PROJECT SUMMARY Dental plaque and associated periodontal diseases represent a common infectious disease afflicting nearly half of American adults (CDC). The complex intra- and interspecies interactions regulate the development of multispecies oral microbial communities called dental plaque. The dental plaque is made of an organized, highly complex microbial social community and the Gram-negative anaerobe F.nucleatum is a key organism of this microbiome by virtue of its unique capability to physically aggregate with many early and late colonizers. Besides its role in periodontitis, F. nucleatum has been linked to several extra-oral diseases including preterm birth and colorectal cancer. Although the fusobacterial interactions with other bacteria have been widely studied and four coaggregation adhesins identified, little is known about mechanisms that regulate Fusobacterium-mediated coaggregation, mainly due to the lack of a robust genetic toolkit for manipulation of F. nucleatum. To overcome this, we recently developed a convenient gene deletion system for F. nucleatum and generated a large library of random transposon mutants with ~10-fold genome coverage. Screening of this library uncovered several coaggregation factors, which include a unique two-component system termed CarS- CarR and a nine-gene-operon that encodes a lysine-degrading pathway (LDP) that controls the amount and activity of RadD, respectively. RadD, a type IV autotransporter, is a versatile adhesin that mediates fusobacterial adhesion with many early and some late colonizers. Based on these findings, we plan to characterize the two regulatory factors in-depth. We will be the first time to show an oral bacterial two component signaling component regulates expression of cell-cell adhesin in a cell density-dependent manner and characterize a lysine riboswitch related to lysine catabolism in bacteria. Upon the successful completion of this research, we expect to have significantly contributed to the understanding of how the versatile adhesin RadD is regulated by identifying and deciphering factors and mechanism involved. Because RadD requires F. nucleatum to incorporate into an established community made of initial commensal colonizers, such as streptococci and actinomyces, our discoveries will have a significant impact on the understanding of fusobacterium-mediated coaggregation role in development of dental plaque, will provide new insights into the development of potent therapeutic strategies against this important pathogen.