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首页> 外文期刊>Proceedings of the National Academy of Sciences of the United States of America >Disparate responses to oxidative stress in saprophytic and pathogenic mycobacteria.
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Disparate responses to oxidative stress in saprophytic and pathogenic mycobacteria.

机译：腐生和致病性分枝杆菌对氧化应激的不同反应。

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摘要

To persist in macrophages and in granulomatous caseous lesions, pathogenic mycobacteria must be equipped to withstand the action of toxic oxygen metabolites. In Gram-negative bacteria, the OxyR protein is a critical component of the oxidative stress response. OxyR is both a sensor of reactive oxygen species and a transcriptional activator, inducing expression of detoxifying enzymes such as catalase/hydroperoxidase and alkyl hydroperoxidase. We have characterized the responses of various mycobacteria to hydrogen peroxide both phenotypically and at the levels of gene and protein expression. Only the saprophytic Mycobacterium smegmatis induced a protective oxidative stress response analogous to the OxyR response of Gram-negative bacteria. Under similar conditions, the pathogenic mycobacteria exhibited a limited, nonprotective response, which in the case of Mycobacterium tuberculosis was restricted to induction of a single protein, KatG. We have also isolated DNA sequences homologous to oxyR and ahpC from M. tuberculosis and Mycobacterium avium. While the M. avium oxyR appears intact, the oxyR homologue of M. tuberculosis contains numerous deletions and frameshifts and is probably nonfunctional. Apparently the response of pathogenic mycobacteria to oxidative stress differs significantly from the inducible OxyR response of other bacteria.
机译：为了在巨噬细胞和肉芽肿性干酪样病灶中持续存在，必须配备致病性分枝杆菌以抵抗有毒的氧代谢产物。在革兰氏阴性细菌中，OxyR蛋白是氧化应激反应的关键组成部分。 OxyR既是活性氧的传感器，又是转录激活因子，可诱导解毒酶（如过氧化氢酶/氢过氧化物酶和烷基氢过氧化物酶）的表达。我们已经表征了各种分枝杆菌对过氧化氢的反应，无论是在表型上还是在基因和蛋白质表达的水平上。只有腐生性耻垢分枝杆菌才诱导出保护性氧化应激反应，类似于革兰氏阴性菌的OxyR反应。在相似的条件下，致病性分枝杆菌表现出有限的非保护性反应，在结核分枝杆菌的情况下，这种反应仅限于诱导单一蛋白KatG的诱导。我们还从结核分枝杆菌和鸟分枝杆菌中分离了与oxyR和ahpC同源的DNA序列。虽然鸟分枝杆菌oxyR看起来完整无缺，但结核分枝杆菌的oxyR同源物包含许多缺失和移码，可能没有功能。显然，致病性分枝杆菌对氧化应激的反应与其他细菌的可诱导OxyR反应明显不同。

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