Dynamics of the bacterial type IX secretion system and its effect on subgingival biofilm formation by bacteria of the human oral microbiome

项目摘要/摘要 细菌IX型蛋白分泌系统(T9SS)，这是一种新发现的蛋白分泌 系统，是在细菌中发现的，这些细菌是人类龈下生物膜的一部分。到目前为止，已经证明 T9SS在牙龈卟啉单胞菌[1，2]、连翘坦纳氏菌[3]和Capnocytophaga sp.中具有功能。 [4]。Pggvalis Arg-gigiain(RGP)和Lys-gigiain(KGP)通过T9SS分泌。RGP和KGP 通过破坏宿主的免疫反应和牙周组织的降解，增加患牙周病的风险 宿主组织和血浆蛋白。T9SS与旋转电机相关联，它的动态特性使 分泌细胞表面粘附素、已知的毒力因子和酶。它还需要用于以下方面 细菌通过一种称为滑动运动的过程在表面上移动。细胞黏附，表面 导航和运动对许多细菌生物膜的形成都很重要。最近的报道 表明细菌运动机器能够通过一种称为 机械传感[6，7]。大肠埃希氏菌和肠沙门氏菌等人类病原体 外表面通过鞭毛马达-III型分泌系统机械[6]，而假单胞菌 铜绿假单胞菌和黄色粘球菌通过IV型菌毛机械感应外表面[7，8]。我们的 初步和已发表的研究结果表明，携带T9SS的滑行细菌具有感知 外部表面和粘性环境[9]。这种细菌没有鞭毛马达或类型 静脉注射菌毛。在人类口腔微生物群的细菌中，属于Capnocytophaga属，它们是 存在于人类的龈下生物膜中[10]，是回答重要问题的一个有吸引力的系统 与生物膜形成、表面传感和水动力学有关。这些细菌有T9SS和 它们在外表面上表现出滑行运动。最近，基因工具被开发出来用于他们的 操纵[4]。我建议研究牙周炎，这是一种重要的，但研究不足的 人类龈下生物膜中存在的细菌[4，10]。我们发现牙龈弯曲菌的T9SS是 由一种新型旋转马达提供动力。此外，我们还发现牙龈假单胞菌细胞使用T9SS分泌的粘附素 聚集并形成组。这种聚集体在外表面上表现出滑动运动。我们的数据 这表明滑翔是由旋转马达提供动力的，而旋转马达通过T9SS为分泌物提供动力。滑翔 运动性，这是T9SS动力学的输出，将被用来检测基因调控和 基因筛查的发展。这样的筛查将针对所涉及的蛋白质进行鉴定 在口腔细菌的感觉传导中。总体而言，T9SS的动态和分泌的蛋白质的作用 T9SS将在龈下生物膜形成的背景下进行研究。

Project Summary/Abstract The bacterial Type IX protein secretion system (T9SS), which is a recently discovered protein secretion system, is found in bacteria that are a part of human subgingival biofilms. So far, it has been shown that T9SS is functional in Porphyromonas gingivalis [1, 2], Tannerella forsythia [3] and Capnocytophaga sp. [4]. P. gingivalis Arg-gingipain (Rgp) and Lys-gingipain (Kgp) are secreted via T9SS. Rgp and Kgp increase the risk of periodontal diseases by disrupting the host immune response and degradation of the host tissue and plasma proteins. T9SS is associated with a rotary motor and its dynamics enables secretion of cell-surface adhesins, known virulence factors and enzymes. It is also required for movement of bacteria over a surface by a process called gliding motility. Cell adhesion, surface navigation and motility are important for the formation of many bacterial biofilms [5]. Recent reports suggest that bacterial motility machineries enable sensing of external surfaces via a process called as mechanosensing [6, 7]. Human pathogens such as Escherichia coli and Salmonella enterica sense external surfaces via the flagellar motor-Type III secretion system machinery [6], while Pseudomonas aeruginosa and Myxococcus xanthus sense external surface via the Type IV pili machinery [7, 8]. Our preliminary and published results suggest that gliding bacteria with T9SS have the ability to sense external surfaces and viscous environments [9]. Such bacteria do not have the flagellar motor or the type IV pili. Amongst bacteria of the human oral microbiome, members of Capnocytophaga genus, which are present in human subgingival biofilms [10], are an attractive system for answering important questions related to biofilm formation, surface-sensing, and hydrodynamics. These bacteria have the T9SS and they exhibit gliding motility over external surfaces. Recently, genetic tools were developed for their manipulation [4]. I propose to study Capnocytophaga gingivalis, which is an important, yet understudied bacterium present in human subgingival biofilms [4, 10]. We discovered that the T9SS of C. gingivalis is powered by a novel rotary motor. Also, we found that C. gingivalis cells use adhesins secreted by T9SS to aggregate and form groups. Such aggregates exhibit gliding motility over external surfaces. Our data suggests that gliding is powered by the same rotary motor that powers secretion via T9SS. Gliding motility, which is the output of the dynamics of T9SS, will be used to assay for gene regulation and for development of genetic screens. Such screens will be targeted towards identification of proteins involved in sensory transduction by oral bacteria. Overall, dynamics of T9SS and role of proteins secreted by T9SS will be studied in the context of subgingival biofilm formation.