Harter Caroline, Melin Frédéric, Hoeser Franziska, Hellwig Petra, Wohlwend Daniel, Friedrich Thorsten
Institut für Biochemie, Albert-Ludwigs-Universität Freiburg, Germany.
Laboratoire de Bioélectrochimie et Spectroscopie, UMR 7140, CMC, Université de Strasbourg CNRS, Strasbourg, France.
FEBS Lett. 2024 Dec;598(23):2856-2865. doi: 10.1002/1873-3468.15013. Epub 2024 Sep 11.
Respiratory complex I is a central metabolic enzyme coupling NADH oxidation and quinone reduction with proton translocation. Despite the knowledge of the structure of the complex, the coupling of both processes is not entirely understood. Here, we use a combination of site-directed mutagenesis, biochemical assays, and redox-induced FTIR spectroscopy to demonstrate that the quinone chemistry includes the protonation and deprotonation of a specific, conserved aspartic acid residue in the quinone binding site (D325 on subunit NuoCD in Escherichia coli). Our experimental data support a proposal derived from theoretical considerations that deprotonation of this residue is involved in triggering proton translocation in respiratory complex I.
呼吸链复合体I是一种核心代谢酶，它将NADH氧化和醌还原与质子转运偶联起来。尽管已经了解了该复合体的结构，但这两个过程的偶联机制尚未完全清楚。在这里，我们结合定点诱变、生化分析和氧化还原诱导傅里叶变换红外光谱，证明醌化学过程包括醌结合位点（大肠杆菌NuoCD亚基上的D325）中一个特定的、保守的天冬氨酸残基的质子化和去质子化。我们的实验数据支持了基于理论推测得出的一个观点，即该残基的去质子化参与触发呼吸链复合体I中的质子转运。
