Mechanisms for the repair of oxidative stress-induced DNA damage in Porphyromonas

牙龈卟啉单胞菌作为一种“关键病原体”，突出了其适应严酷的炎症环境的能力。 牙周袋的情况。因为环境压力反应是其主要决定因素， 因此，我们的长期目标是全面了解其生存策略。DNA 损伤是氧化应激的主要后果。而超过20种不同的氧化改变的碱基 8-oxo-7，8-dihydroguanine（8-oxoG）是最常见的应激产物之一。 DNA损伤。鸟嘌呤是最易氧化的碱基，由于其氧化还原性低，主要形成8-oxoG 潜力在原核细胞中，8-oxoG的存在主要通过碱基切除修复（BER）来修复。一 牙龈卟啉单胞菌基因组的调查表明BER系统的一个重要组成部分缺失。因为 牙龈卟啉单胞菌基因组的平均G + C含量为49%，这是预防或修复损伤的机制 是至关重要的。我们在全面了解一个或多个机制方面存在差距， 牙龈卟啉单胞菌中氧化应激诱导的DNA损伤的修复。我们之前已经证明， 是暴露于H2 O2诱导的氧化应激的牙龈卟啉单胞菌染色体中8-oxoG的积累。 BER和核苷酸切除修复（NER），如在其他菌株中观察到的那样，似乎都不参与细胞的增殖。 修复牙龈卟啉单胞菌中的8-oxoG损伤。DNA亲和分离鉴定了PG 1037，一个保守的假设的 蛋白质等，其优先结合到携带8-oxo-G损伤的寡核苷酸片段。 PG 1037是牙龈卟啉单胞菌中uvrA-pg 1037-pcrA操纵子的一部分，已知其在H2 O2下上调。 诱导压力。纯化的重组PG 1037蛋白可能通过还原功能，具有防止 芬顿化学在体外介导的DNA损伤，并在氧化应激条件下，减少切割 通过大肠杆菌甲酰氨基嘧啶糖基化酶（Fpg）的8-oxoG损伤。PG 1037的计算机模拟分析 显示了含有锌指结构域、两个过氧化物酶同源基序和胞苷酸激酶的蛋白质 域该提案的目的是检验一种新的牙龈卟啉单胞菌蛋白（PG 1037） 携带过氧化物酶基序和锌指结构域参与氧化损伤的修复 DNA.我们的目的是确认PG 1037在从双链体DNA去除8-oxoG中的特定作用， 评估PG 1037与该过程中其他蛋白质的任何相互作用。这些数据将提供一个重要的概念 牙龈卟啉单胞菌氧化应激诱导DNA损伤修复的分子基础研究进展 可能支持一种独特而有效的DNA修复机制，我们建议将其命名为“碱基氧化还原修复”。 它将在未来的RO 1应用中为解决生命周期中特定的结构-功能问题奠定基础。 在维持暴露于环境中的厌氧菌的基因组稳定性中的组分及其合作 应力这些成分可能是开发新的治疗干预措施的目标， 和预防牙龈卟啉单胞菌相关疾病。

Porphyromonas gingivalis, as a “keystone pathogen”, highlights its ability to adapt to the harsh inflammatory conditions of the periodontal pocket. Because the environmental stress response is a major determinant of its virulence, it is our long-term goal to gain a comprehensive understanding of its survival strategy(s). DNA damage is a major consequence of oxidative stress. While more than 20 different oxidatively altered bases might be generated by this stress, 8-oxo-7,8-dihydroguanine (8-oxoG) is one of the most common product of DNA damage. Guanine is the most susceptible base to oxidation and forms mainly 8-oxoG due to its low redox potential. In prokaryotic cells the presence of 8-oxoG is mainly repaired by base excision repair (BER). A survey of the P. gingivalis genome indicate that an important component of the BER system is missing. Because the average G + C content of the genome of P. gingivalis is 49%, a mechanism(s) to prevent or repair lesions resulting from guanine oxidation is vital. There is a gap in our comprehensive knowledge on a mechanism(s) for the repair of oxidative stress-induced DNA damage in P. gingivalis. We have previously demonstrated that there is an accumulation of 8-oxoG in the chromosome of P. gingivalis exposed to H2O2-induced oxidative stress. Neither BER nor nucleotide excision repair (NER), as observed in other strains, appear to be involved in the repair of the 8-oxoG lesion in P. gingivalis. DNA affinity fractionation identified PG1037, a conserved hypothetical protein, among others, that were preferentially bound to the oligonucleotide fragment carrying the 8-oxo-G lesion. PG1037 is part of the uvrA-pg1037-pcrA operon in P. gingivalis which is known to be upregulated under H2O2- induced stress. The purified recombinant PG1037 protein, likely via a reducing function, has the ability to prevent Fenton chemistry-mediated DNA damage in vitro and, under oxidative stress conditions, reduced the cleavage of the 8-oxoG lesion by the E.coli foramidopyrimidine glycosylase (Fpg) enzyme. In silico analysis of PG1037 shows a protein that contains a zinc finger domain, two peroxidase homologous motifs and a cytidylate kinase domain. The goal of the proposal is to test the hypothesis that a novel P. gingivalis protein (PG1037) carrying peroxidase motifs and a zinc finger domain is involved in the repair of oxidatively damaged DNA. Our aims are to confirm the specific role of PG1037 in the removal of 8-oxoG from duplex DNA and to evaluate any interaction of PG1037 with other proteins in that process. The data will provide a major conceptual advance on the molecular bases for the repair of oxidative stress-induced DNA damage in P. gingivalis and could likely support a unique and effective DNA repair mechanism we propose to designate “base redox repair”. It will set the stage, in a future RO1 application, to address specific structure-function questions on the vital components and their corporation in maintaining genomic stability in anaerobes exposed to environmental stress. These components could be targets for the development of novel therapeutic interventions for the control and prevention of P. gingivalis-associated diseases.