Mechanisms for adaptation to oxidative stress in Porphyromonas gingivalis

描述(由申请人提供)：牙龈卟啉单胞菌对氧化应激的适应机制牙龈卟啉单胞菌是一种黑色素、革兰氏阴性厌氧菌，是牙周病的重要病原体。牙周袋的炎症环境表明，这种有机体具有促进其在氧化环境中生存的能力的特性。在牙周炎和其他牙周病原体中，我们对氧化应激抵抗的机制(S)的认识还存在空白。我们的假设是，在牙龈假单胞菌中，多种协同调节机制对于保护机体免受氧化应激至关重要，并且在生物体的致病性中具有重要意义。在初步研究中，我们使用了一种全球方法来评估牙周袋典型氧化应激环境中牙龈假单胞菌等基因突变株细胞反应的转录图谱。对过氧化氢(H_2O_2)诱导的氧化应激的反应确定了几个基因的诱导表达，其中包括一些已知参与氧化应激抵抗的基因。氧化应激的持续时间对转录有不同的调节作用，DNA修复/修饰基因的上调大多出现在较短的暴露时间。在较长时间的氧化应激中，几个已知参与蛋白质修复的基因被上调。在暴露时间的范围内，有几个假设的基因上调，这些基因以前没有被表征。我们以前的报告也证明，与其他生物不同，8-氧代-7，8-二氢鸟嘌呤(8-oxoG)对氧化应激诱导的DNA损伤的修复可能通过一种尚未被描述的机制在牙龈假单胞菌中发生。在这个项目中，我们希望全面了解牙龈假单胞菌是如何适应牙周袋典型的氧化条件的，并评估它是否与其致病性有关。本研究的具体目的是：1.研究氧化应激诱导基因在牙龈假单胞菌生存/致病中的作用(S)。2.鉴定与GRPE基因表达相关的调控序列和蛋白(S)。3.研究牙龈假单胞菌同基因突变株在氧化应激条件下的DNA损伤及修复机制(S)。总而言之，这些信息可以提供重要的线索，使新的治疗干预措施的开发能够帮助控制和预防牙周病和其他牙龈假单胞菌相关疾病。 公共卫生相关性：这项研究的目标是确定有助于牙周病原体牙龈卟啉单胞菌在牙周袋炎症环境中生存的重要因素。因为这种环境可能会对有机体造成严重的损害，而且它成功地成为牙周病的重要原因，这表明牙龈假单胞菌具有促进其在压力环境中生存的能力的特性。对生存至关重要的重要因素是开发将对人类健康产生积极影响的新疗法的主要目标。

DESCRIPTION (provided by applicant): Mechanisms for adaptation to oxidative stress in Porphyromonas gingivalis Porphyromonas gingivalis, a black-pigmented, Gram-negative anaerobe, is an important etiologic agent of periodontal disease. The inflammatory environment of the periodontal pocket suggests that this organism has properties that will facilitate its ability live in an oxidative environment. There is a gap in our knowledge of mechanism(s) of oxidative stress resistance in P. gingivalis and other periodontal pathogens. It is our hypothesis that in P. gingivalis multiple coordinately regulated mechanisms are vital for protection against oxidative stress and are significant in the pathogenicity of the organism. In preliminary studies, we have used a global approach to assess the transcription profile of the cellular response of isogenic mutants of P. gingivalis in an environment of oxidative stress typical of the periodontal pocket. The response to hydrogen peroxide (H2O2)-induced oxidative stress identified the induced expression of several genes including some known to be involved in oxidative stress resistance. The duration of oxidative stress was shown to differentially modulate transcription with the up-regulation of DNA repair/modification genes mostly seen at a shorter exposure time. During a longer exposure to oxidative stress, several genes known to be involved in protein repair were up-regulated. Over the range of exposure times, there was an up-regulation of several hypothetical genes which have not been previously characterized. Our previous report has also demonstrated that, in contrast to other organisms, the repair of oxidative stress-induced DNA damage involving 8-oxo-7,8-dihydroguanine (8-oxoG) may occur by a yet-to-be described mechanism in P. gingivalis. In this project, we wish to gain a comprehensive understanding of how P. gingivalis adapts to the oxidative conditions typical of the periodontal pocket and evaluate whether it contributes to its pathogenicity. The Specific Aims are: 1. To characterize the specific role(s) of oxidative stress-induced genes in the survival/pathogenicity of P. gingivalis. 2. To identify and characterize the regulatory sequences and protein(s) involved in the expression of the grpE locus. 3. To characterize the DNA damage and mechanism(s) of repair in isogenic mutants of P. gingivalis under conditions of oxidative stress. Collectively, this information could provide important clues that would allow the development of novel therapeutic interventions to aid in the control and prevention of periodontal disease and other P. gingivalis-associated diseases. PUBLIC HEALTH RELEVANCE: The goal of this research is to characterize important factors that will facilitate the survival of the periodontal pathogen Porphyromonas gingivalis in the inflammatory environment of the periodontal pocket. Because this environment may cause severe damage to the organism and given its success as important cause of gum disease suggests that P. gingivalis has properties that will facilitate its ability live in a stress environment. Important factors that are essential for survival are prime targets for the development of novel therapeutics that will have a positive impact on human health.