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Role of Superoxide Dismutase Activity in the Physiology of Porphyromonas gingivalis

机译：超氧化物歧化酶活性在牙龈卟啉单胞菌生理中的作用

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Porphyromonas gingivalis is a gram-negative, obligate anaerobe strongly associated with chronic adult periodontitis. A previous study has demonstrated that this organism requires superoxide dismutase (SOD) for its modest aerotolerance. In this study, we have constructed a mutant deficient in SOD activity by insertional inactivation as well as a sod::lacZreporter translational fusion construct to study the regulation of expression of this gene. We have confirmed that SOD is essential for tolerance to atmospheric oxygen but does not appear to be protective against hydrogen peroxide or exogenously generated reactive oxygen species. Furthermore, the sod mutant appeared to be no more sensitive to killing by neutrophils than the parental strain 381. SOD appears to be protective against oxygen-dependent DNA damage as measured by increased mutation to rifampin resistance by thesod mutant. Use of thesod::lacZ construct confirmed that SOD expression is maximal at mid-log phase and is influenced by oxygen, temperature, and pH. However, expression does not appear to be significantly affected by iron depletion, osmolarity, or nutrient depletion. The transcription start site of the sod gene was determined to be 315 bp upstream of the sod start codon and to be within an upstream open reading frame. Our studies demonstrate the essential role that SOD plays in aerotolerance of this organism as well as the selective induction of this enzyme by environmental stimuli.
机译：牙龈卟啉单胞菌是革兰氏阴性，专性厌氧菌，与成人慢性牙周炎密切相关。先前的研究表明，这种生物需要适度的耐氧性超氧化物歧化酶（SOD）。在这项研究中，我们通过插入失活和 sod :: lacZ reporter翻译融合构建体构建了SOD活性不足的突变体，以研究其表达调控基因。我们已经证实，SOD对耐受大气中的氧气至关重要，但似乎对过氧化氢或外源性产生的活性氧没有保护作用。此外，与亲本菌株381相比， sod 突变体对嗜中性粒细胞的杀灭似乎并不敏感。SOD似乎对氧依赖性DNA损伤具有保护作用，这是通过< em> sod 突变体。使用 sod :: lacZ 构建体证实，SOD表达在对数中期处于最大状态，并受氧气，温度和pH值的影响。但是，铁的耗竭，渗透压或营养耗竭似乎并未明显影响表达。确定 sod 基因的转录起始位点位于 sod 起始密码子上游315 bp，位于上游开放阅读框内。我们的研究表明，SOD在该生物体的耐气性以及环境刺激对这种酶的选择性诱导中起着至关重要的作用。

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