Riboregulation in periodontopathogen Porphyromonas gingivalis

描述(申请人提供)：牙龈卟啉单胞菌是一种革兰氏阴性厌氧菌，是公认的牙周病原体。虽然它主要存在于无氧牙周袋中，但它也存在于口腔的其他壁龛中，在进入牙周袋的过程中，它还可以接触到身体的远处部分，如心血管系统和心脏组织。最后，它可以入侵并在宿主细胞内存活。为了适应不同的生态位，生物体被期望有有效的调节机制，使它能够快速改变基因和最终的蛋白质表达，以响应宿主环境施加的各种挑战。核转录调控已成为细菌转运后调控的一种重要机制。RNA伴侣Hfq通过结合sRNA和稳定sRNA-mRNA双链在这一过程中发挥着不可或缺的作用。然而，至少50%的细菌缺乏Hfq，这表明存在其他新的机制来调节sRNA。利用生物信息学方法，我们确定了牙龈假单胞菌中一种RNA结合蛋白的候选者，这里指定为PGR。我们的初步数据表明，该蛋白与rna结合，并在亚硝化应激条件下对细菌的生存起作用。 以及在宿主细胞存在的情况下。此外，我们注意到由于PGR缺失而导致的RNA水平的显著变化。根据初步数据，我们推测PGR是一种新的RNA伴侣，在牙龈假单胞菌的转录后调控中发挥主要作用。由于PGR功能与细菌的完全毒力相关，它将成为开发抗菌策略的极佳靶点。为了深入了解蛋白质的调控机制，我们将定义受蛋白质缺乏影响的转录组和蛋白质组，并鉴定与PGR相互作用的RNA。我们期望这项工作一旦完成，将对该蛋白的作用机制提供深入的了解，并最终将导致干扰其作用的策略的设计，从而降低牙龈假单胞菌的毒力。最后，我们预测这项工作将有助于揭示其他类杆菌相关细菌如中间普氏杆菌、福赛坦纳杆菌、脆弱类杆菌、B.thetaiotaomicron和Capnocytophaga hutchinsonii的核转录调控机制。

DESCRIPTION (provided by applicant): Porphyromonasgingivalis, a gram-negative anaerobic bacterium, is a recognized periodontopathogen. Although it mainly inhabits anaerobic periodontal pockets it also is present in other niches of the oral cavity enroute to the periodonta pockets as well as it can access distant parts of the body such as cardiovascular system and heart tissues. Finally, it can invade and survive within host cells. In order to adapt to the varios niches the organism is expected to have efficient regulatory mechanisms allowing it to rapidly alter gene and ultimately protein expression in response to the various challenges imposed by the host environments. Riboregulation has emerged as a significant mechanism of post-transciptional regulation in bacteria. The RNA chaperone, Hfq, has been shown to play an indispensable role in this process by binding sRNAs and stabilizing the sRNA-mRNA duplexes. However, at least 50% of bacteria lack Hfq indicating the presence of other novel mechanisms mediating sRNA regulation. Using bioinformatics approaches we identified a candidate for an RNA-binding protein, designated here as Pgr, in P.gingivalis. Our preliminary data demonstrate that the protein binds RNA and plays a role in survival of the bacterium with nitrosative stress as well as in the presence of host cells. Furthermore, we noted significant changes in RNA levels resulting from deletion of Pgr. Based on the preliminary data we hypothesize that Pgr is a novel RNA chaperone and plays a major role in post-transcriptional regulation in P. gingivalis. As Pgr function is relevant for full virulence of the bacterium, it will serve as an excellent target for development of antimicrobial strategies. To gain an insight into the mechanism of regulation by the protein we will define the transcriptome and proteome affected by the absence of the protein as well as identify the RNAs interacting with Pgr. We expect that once completed this work will provide insight into mechanism of action of this protein and ultimately will lead to design of strategies interfering with its action and thus reducing virulence of P. gingivalis. Finally, we predict that this work will shed light on the mechanisms of riboregulation in other Bacteroides- related bacteria such as Prevotella intermedia, Tannerella forsythensis, Bacteroides fragilis, B. thetaiotaomicron and Capnocytophaga hutchinsonii.