Abstract：
OBJECTIVE: Treponema denticola has been strongly implicated in the pathogenesis of chronic periodontitis. Previously, we reported that the potential transcriptional regulator TDE_0259 (oxtR1) is upregulated in the bacteriocin ABC transporter gene-deficient mutant. OxtR1 may regulate genes to adapt to environmental conditions during colonization; however, the exact role of the gene in T. denticola has not been reported. Therefore, we investigated its function using an oxtR1-deficient mutant.
METHODS: The growth rates of the wild-type and oxtR1 mutant were monitored under anaerobic conditions; their antibacterial agent susceptibility and gene expression were assessed using a liquid dilution assay and DNA microarray, respectively. An electrophoretic mobility shift assay was performed to investigate the binding of OxtR1 to promoter regions.
RESULTS: The growth rate of the bacterium was accelerated by the inactivation of oxtR1, and the mutant exhibited an increased minimum inhibitory concentration against ofloxacin. We observed a relative increase in the expression of genes associated with potential ferrodoxin (TDE_0260), flavodoxin, ABC transporters, heat-shock proteins, DNA helicase, iron compounds, and lipoproteins in the mutant. OxtR1 expression increased upon oxygen exposure, and oxtR1 complementation suppressed the expression of potential ferrodoxin. Our findings also suggested that OxtR1 binds to a potential promoter region of the TDE_0259-260 operon. Moreover, the mutant showed a marginal yet significantly faster growth rate than the wild-type strain under H2O2 exposure.
CONCLUSIONS: The oxygen-sensing regulator OxtR1 plays a role in regulating the expression of a potential ferrodoxin, which may contribute to the response of T. denticola to oxygen-induced stress.
METHODS: The growth rates of the wild-type and oxtR1 mutant were monitored under anaerobic conditions; their antibacterial agent susceptibility and gene expression were assessed using a liquid dilution assay and DNA microarray, respectively. An electrophoretic mobility shift assay was performed to investigate the binding of OxtR1 to promoter regions.
RESULTS: The growth rate of the bacterium was accelerated by the inactivation of oxtR1, and the mutant exhibited an increased minimum inhibitory concentration against ofloxacin. We observed a relative increase in the expression of genes associated with potential ferrodoxin (TDE_0260), flavodoxin, ABC transporters, heat-shock proteins, DNA helicase, iron compounds, and lipoproteins in the mutant. OxtR1 expression increased upon oxygen exposure, and oxtR1 complementation suppressed the expression of potential ferrodoxin. Our findings also suggested that OxtR1 binds to a potential promoter region of the TDE_0259-260 operon. Moreover, the mutant showed a marginal yet significantly faster growth rate than the wild-type strain under H2O2 exposure.
CONCLUSIONS: The oxygen-sensing regulator OxtR1 plays a role in regulating the expression of a potential ferrodoxin, which may contribute to the response of T. denticola to oxygen-induced stress.
摘要：
目的：树突状螺旋体与慢性牙周炎的发病机制密切相关。以前,我们报道了潜在的转录调节因子TDE_0259（oxtR1）在细菌素ABC转运体基因缺陷突变体中上调。OxtR1可能在定殖过程中调节基因以适应环境条件;然而，该基因在斑节弧菌中的确切作用尚未见报道。因此,我们使用oxtR1缺陷突变体研究了其功能。
方法：在厌氧条件下监测野生型和oxtR1突变体的生长速率；使用液体稀释测定和DNA微阵列评估其抗菌剂敏感性和基因表达，分别。进行电泳迁移率变化测定以研究OxtR1与启动子区域的结合。
结果：oxtR1的失活加速了细菌的生长速度，并且突变体对氧氟沙星的最低抑菌浓度增加。我们观察到与潜在的铁氧还蛋白（TDE_0260）相关的基因表达相对增加，黄素还蛋白,ABC运输商，热休克蛋白，DNA解旋酶,铁化合物,和突变体中的脂蛋白。氧暴露后OxtR1表达增加，oxtR1互补抑制了潜在的亚铁蛋白的表达。我们的发现还表明OxtR1与TDE_0259-260操纵子的潜在启动子区域结合。此外，在H2O2暴露下，突变体的生长速度比野生型菌株快。
结论：氧传感调节因子OxtR1在调节潜在的铁氧化还原蛋白的表达中起作用，这可能有助于T.denticola对氧诱导的应激的反应。
方法：在厌氧条件下监测野生型和oxtR1突变体的生长速率；使用液体稀释测定和DNA微阵列评估其抗菌剂敏感性和基因表达，分别。进行电泳迁移率变化测定以研究OxtR1与启动子区域的结合。
结果：oxtR1的失活加速了细菌的生长速度，并且突变体对氧氟沙星的最低抑菌浓度增加。我们观察到与潜在的铁氧还蛋白（TDE_0260）相关的基因表达相对增加，黄素还蛋白,ABC运输商，热休克蛋白，DNA解旋酶,铁化合物,和突变体中的脂蛋白。氧暴露后OxtR1表达增加，oxtR1互补抑制了潜在的亚铁蛋白的表达。我们的发现还表明OxtR1与TDE_0259-260操纵子的潜在启动子区域结合。此外，在H2O2暴露下，突变体的生长速度比野生型菌株快。
结论：氧传感调节因子OxtR1在调节潜在的铁氧化还原蛋白的表达中起作用，这可能有助于T.denticola对氧诱导的应激的反应。
