Portela Pilar C, Morgado Leonor, Silva Marta A, Denkhaus Lukas, Einsle Oliver, Salgueiro Carlos A
Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal.
UCIBIO - Applied Molecular Biosciences Unit, Department of Chemistry, NOVA School of Science and Technology, Universidade NOVA de Lisboa, Caparica, Portugal.
Front Microbiol. 2023 Oct 4;14:1253114. doi: 10.3389/fmicb.2023.1253114. eCollection 2023.
The recent reclassification of the strict anaerobe bacterium as aerotolerant brought attention for oxidative stress protection pathways. Although the electron transfer pathways for oxygen detoxification are not well established, evidence was obtained for the formation of a redox complex between the periplasmic triheme cytochrome PpcA and the diheme cytochrome peroxidase MacA. In the latter, the reduction of the high-potential heme triggers a conformational change that displaces the axial histidine of the low-potential heme with peroxidase activity. More recently, a possible involvement of the triheme periplasmic cytochrome family (PpcA-E) in the protection from oxidative stress in was suggested. To evaluate this hypothesis, we investigated the electron transfer reaction and the biomolecular interaction between each PpcA-E cytochrome and MacA. Using a newly developed method that relies on the different NMR spectral signatures of the heme proteins, we directly monitored the electron transfer reaction from reduced PpcA-E cytochromes to oxidized MacA. The results obtained showed a complete electron transfer from the cytochromes to the high-potential heme of MacA. This highlights PpcA-E cytochromes' efficient role in providing the necessary reducing power to mitigate oxidative stress situations, hence contributing to a better knowledge of oxidative stress protection pathways in .
最近将严格厌氧菌重新分类为耐氧菌引发了对氧化应激保护途径的关注。尽管氧气解毒的电子传递途径尚未完全明确，但已获得证据表明周质三血红素细胞色素PpcA和二血红素细胞色素过氧化物酶MacA之间形成了氧化还原复合物。在后者中，高电位血红素的还原引发构象变化，取代了具有过氧化物酶活性的低电位血红素的轴向组氨酸。最近，有人提出三血红素周质细胞色素家族（PpcA-E）可能参与了对氧化应激的保护。为了评估这一假设，我们研究了每个PpcA-E细胞色素与MacA之间的电子传递反应和生物分子相互作用。使用一种新开发的方法，该方法依赖于血红素蛋白不同的核磁共振光谱特征，我们直接监测了从还原的PpcA-E细胞色素到氧化的MacA的电子传递反应。获得的结果表明电子从细胞色素完全转移到MacA的高电位血红素上。这突出了PpcA-E细胞色素在提供必要的还原能力以减轻氧化应激情况方面的有效作用，从而有助于更好地了解氧化应激保护途径。
