The survival/adaptation of Filifactor alocis, a fastidious Gram-positive asaccharolytic anaerobe, to the inflammatory environment of the periodontal pocket requires an ability to overcome oxidative stress. Moreover, its pathogenic characteristics are highlighted by its capacity to survive in the oxidative-stress microenvironment of the periodontal pocket and a likely ability to modulate the microbial community dynamics. There is still a significant gap in our understanding of its mechanism of oxidative stress resistance and its impact on the virulence and pathogenicity of the microbial biofilm. Coinfection of epithelial cells with F. alocis and Porphyromonas gingivalis resulted in the upregulation of several genes, including HMPREF0389_01654 (FA1654). Bioinformatics analysis indicates that FA1654 has a “di-iron binding domain” and could function as a DNA starvation and stationary phase protection (DPS) protein. We have further characterized the FA1654 protein to determine its role in oxidative stress resistance in F. alocis. In the presence of hydrogen peroxide-induced oxidative stress, there was an ∼1.3 fold upregulation of the FA1654 gene in F. alocis. Incubation of the purified FA1654 protein with DNA in the presence of hydrogen peroxide and iron resulted in the protection of the DNA from Fenton-mediated degradation. Circular dichroism and differential scanning fluorimetry studies have documented the intrinsic ability of rFA1654 protein to bind iron; however, the rFA1654 protein is missing the intrinsic ability to reduce hydrogen peroxide. Collectively, the data may suggest that FA1654 in F. alocis is involved in oxidative stress resistance via an ability to protect against Fenton-mediated oxidative stress-induced damage.

中文翻译：

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FA1654 的表征：Filifactor alocis 中的一种推定 DPS 蛋白

Filifactor alocis是一种苛刻的革兰氏阳性糖分解厌氧菌，其生存/适应牙周袋的炎症环境需要克服氧化应激的能力。此外，它在牙周袋氧化应激微环境中的生存能力以及调节微生物群落动力学的可能能力突出了其致病特征。我们对其抗氧化应激机制及其对微生物生物膜毒力和致病性的影响的理解仍然存在显着差距。上皮细胞与F. alocis和Porphyromonas gingivalis的共感染导致几个基因的上调，包括HMPREF0389_01654 (FA1654)。生物信息学分析表明，FA1654 具有“二铁结合域”，可作为 DNA 饥饿和固定相保护 (DPS) 蛋白发挥作用。我们进一步表征了 FA1654 蛋白，以确定其在F. alocis 的氧化应激抗性中的作用。在存在过氧化氢诱导的氧化应激的情况下， F. alocis中的FA1654基因上调了约 1.3 倍. 在存在过氧化氢和铁的情况下，将纯化的 FA1654 蛋白与 DNA 一起孵育可保护 DNA 免受芬顿介导的降解。圆二色性和差示扫描荧光法研究证明了 rFA1654 蛋白结合铁的内在能力；然而，rFA1654 蛋白缺少减少过氧化氢的内在能力。总的来说，数据可能表明F. alocis中的 FA1654通过防止芬顿介导的氧化应激诱导的损伤的能力参与氧化应激抵抗。