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Author:
Date:
2015-10-05
[Abstract] Heme is an iron-containing porphyrin which acts as a prosthetic group in several enzymes involved in disparate functions, such as respiration and H2O2-scavenging. Escherichia coli is able to produce heme endogenously since it contains all the enzymes involved in the nine-step biosynthesis pathway, which in absence of stress and in iron-replete media proceeds unabated. However, we recently showed that two steps are affected by H2O2 stress (Mancini and Imlay, 2015). To compensate, two enzymes, namely the ferrochelatase (HemH) and an isozyme of coproporphyrinogen III oxidase (HemF), are activated by the H2O2-responsive regulator OxyR. Genetic mutations that block either adaptation cause the intracellular accumulation ...
[摘要] 血红素是含铁的卟啉，其在参与不同功能（例如呼吸和H 2 O 2 O 2 - 清除）的几种酶中充当辅基。大肠杆菌能够内源性产生血红素，因为其含有涉及九步生物合成途径的所有酶，其在没有应激的情况下和在铁补充培养基中不减弱地进行。然而，我们最近显示两个步骤受H 2 O 2 O 2胁迫的影响（Mancini和Imlay，2015）。为了补偿，两种酶，即铁螯合酶（HemH）和粪卟啉原III氧化酶（HemF）的同工酶被H 2 O 2反应性调节剂OxyR激活。阻断任一适应的遗传突变导致原卟啉IX和粪卟啉原III的细胞内积累，分别是HemH和HemF的底物。我们在这里描述一种方法，用于提取和量化原卟啉IX和粪卟啉III，coproporphyrinogen III的自发氧化的产物。
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