Instituto de Tecnologia Química e Biológica António Xavier, Universidade Nova de Lisboa, Oeiras, Portugal.
Associate Laboratory i4HB - Institute for Health and Bioeconomy, NOVA School of Science and Technology, Universidade Nova de Lisboa, Caparica, Portugal.
Nat Chem Biol. 2024 Jan;20(1):111-119. doi: 10.1038/s41589-023-01484-2. Epub 2023 Nov 20.
Metal-dependent formate dehydrogenases reduce CO with high efficiency and selectivity, but are usually very oxygen sensitive. An exception is Desulfovibrio vulgaris W/Sec-FdhAB, which can be handled aerobically, but the basis for this oxygen tolerance was unknown. Here we show that FdhAB activity is controlled by a redox switch based on an allosteric disulfide bond. When this bond is closed, the enzyme is in an oxygen-tolerant resting state presenting almost no catalytic activity and very low formate affinity. Opening this bond triggers large conformational changes that propagate to the active site, resulting in high activity and high formate affinity, but also higher oxygen sensitivity. We present the structure of activated FdhAB and show that activity loss is associated with partial loss of the metal sulfido ligand. The redox switch mechanism is reversible in vivo and prevents enzyme reduction by physiological formate levels, conferring a fitness advantage during O exposure.
金属依赖型甲酸盐脱氢酶具有高效和选择性地还原 CO 的能力，但通常对氧气非常敏感。脱硫弧菌（Desulfovibrio vulgaris）W/Sec-FdhAB 是一个例外，它可以在需氧条件下处理，但这种氧气耐受性的基础尚不清楚。在这里，我们表明 FdhAB 的活性受到基于变构二硫键的氧化还原开关的控制。当这个键关闭时，酶处于一种对氧气耐受的静止状态，几乎没有催化活性和非常低的甲酸盐亲和力。打开这个键会触发大的构象变化，这些变化会传播到活性位点，从而导致高活性和高甲酸盐亲和力，但也会增加对氧气的敏感性。我们展示了激活的 FdhAB 的结构，并表明活性丧失与金属硫代配体的部分丧失有关。氧化还原开关机制在体内是可逆的，可以防止生理甲酸盐水平下的酶还原，在 O 暴露期间赋予适应性优势。
