Probing Respiration and Metabolism of a Periodontal Pathogen

项目摘要 牙周炎是一种高度流行的疾病，影响近一半的美国成年人，如果不及时治疗， 骨丢失和组织损伤[1]。多种微生物与这种疾病有关[2，3]， 化学介导的相互作用在牙周裂隙内形成复杂的物种间群落。由于 由于这些化学介导的相互作用的复杂性，牙周炎仍然是难以治疗的疾病。 使用多微生物群落[4，5]和动物模型[5，6]探索了可能的化学相互作用 并且极大地促进了我们对牙周炎期间发生的化学相互作用的理解。在 Whiteley实验室我们使用由格氏链球菌（Streptococci gordonii，Sg）组成的两种模型系统， 革兰氏阳性链球菌能够消耗糖并产生酸，如L-乳酸 产生过氧化氢（H2 O2），以及革兰氏阴性放线菌（Aa） 与侵袭性牙周炎相关的口腔病原体。在此之前，我们已经证明，当生长在共同- 在培养中，Sg交叉喂养Aa其优选的碳源L-乳酸盐，同时另外提供社交线索H2 O2 [7][9][10][11][12][13][14][15][16][17]通过交叉喂养L-乳酸，生长缓慢的Aa能够更好地 在多微生物环境中竞争。此外，H2 O2通过刺激产生而充当线索 保护Aa免受补体杀伤的补体因子ApiA [4]，并诱导产生 蛋白分散素B，允许Aa控制其空间定位[9]。除了这些健身的好处，我们 我还根据以前的数据假设，Sg产生的H2 O2也是Aa的O2的直接来源 通过过氧化氢酶介导的解毒作用[8]。虽然L-乳酸盐和H2 O2已经显示出提供重要的 Aa的代谢线索，最近的基因组工作表明，可能有额外的化学相互作用 这些细菌之间发生的共同感染[8，10]。我们的假设是，Aa显示定义 对Sg的响应对于在微米尺度上建立精确的空间结构生物膜至关重要。 该项目的第一个目标是检验假设，即Aa可以利用来自H2 O2解毒的O2作为 当Aa与Sg共培养时，呼吸的变化以及H2 O2如何影响空间 结构在第二个目标中，我们将使用质谱法来全面了解 Aa和Sg之间发生的化学相互作用。这些研究的结果将提供直接的见解， Aa通过H2 O2解毒获得额外益处的过程。通过识别 Aa和Sg之间未知的化学相互作用，我们可以更好地了解复杂的物种间 牙周炎中的相互作用。

Project Summary Periodontitis is a highly prevalent disease affecting nearly half of all American adults, and if left untreated leads to bone loss and tissue damage [1]. Multiple microbes are associated with this disease [2, 3] and through chemically-mediated interactions form complex interspecies communities within the periodontal crevice. Due to the complexity of these chemically-mediated interactions, periodontitis remains a difficult disease to treat. Efforts using polymicrobial communities [4, 5] and animal models [5, 6] have explored possible chemical interactions and have greatly advanced our understanding of the chemical interactions occurring during periodontitis. In the Whiteley lab we use a two-species model system composed of Streptococci gordonii (Sg), a representative Gram-positive streptococcal species capable of consuming sugars and producing acids such as L-lactate as well as producing hydrogen peroxide (H2O2), and Aggregatibacter actinomycetemcommitans (Aa), a Gram-negative oral pathogen associated with aggressive periodontitis. Previously, we have shown that when grown in co- culture, Sg cross-feeds Aa its preferred carbon source, L-lactate, while additionally providing the social cue H2O2 thereby enhancing the fitness of Aa [7-9]. By being cross-fed L-lactate, the slow-growing Aa is able to better compete within a polymicrobial environment. Furthermore, H2O2 serves as a cue by stimulating the production of the complement factor ApiA that protects Aa from complement killing [4], and induces the production of the protein Dispersin B that allows Aa to control its spatial localization [9]. In addition to these fitness benefits, we also hypothesize based on previous data that Sg-produced H2O2 also serves as a direct source of O2 for Aa through catalase mediated detoxification [8]. While L-lactate and H2O2 have been shown to provide important metabolic cues for Aa, recent genomic work indicates that there are likely additional chemical interactions occurring between these bacteria during co-infection [8, 10]. Our hypothesis is that Aa displays defined responses to Sg that are critical to establishing precise spatially structured biofilms at the micron scale. The first objective of the project is to test the hypothesis that Aa can use O2 derived from H2O2 detoxification as evidenced by a shift in respiration when Aa is grown in co-culture with Sg, and how H2O2 impacts spatial structure. In the second objective we will use mass spectrometry to develop a comprehensive understanding of the chemical interactions occurring between Aa and Sg. The results from these studies will provide direct insight into the processes underlying the additional benefits Aa receives through H2O2 detoxification. By identifying the unknown chemical interactions between Aa and Sg, we can better understand the complex interspecies interactions involved in periodontitis.