Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China.
Division of Respiratory and Critical Care Medicine, State Key Laboratory of Biotherapy, West China Hospital of Sichuan University and Collaborative Innovation Center of Biotherapy, Chengdu 610041, China; Department of Neurology, Affiliated Hospital of North Sichuan Medical College, Institute of Neurological Diseases, North Sichuan Medical College, Nanchong 637000, China.
Structure. 2023 Oct 5;31(10):1220-1232.e5. doi: 10.1016/j.str.2023.08.004. Epub 2023 Aug 30.
Structural diverse natural products like ribosomally synthesized and posttranslationally modified peptides (RiPPs) display a wide range of biological activities. Currently, the mechanism of an uncommon reaction step during the biosynthesis of 3-thiaglutamate (3-thiaGlu) is poorly understood. The removal of the β-carbon from the Cys in the TglA-Cys peptide catalyzed by the TglHI holoenzyme remains elusive. Here, we present three crystal structures of TglHI complexes with and without bound iron, which reveal that the catalytic pocket is formed by the interaction of TglH-TglI and that its activation is conformation dependent. Biochemical assays suggest a minimum of two iron ions in the active cluster, and we identify the position of a third iron site. Collectively, our study offers insights into the activation and catalysis mechanisms of the non-heme dioxygen-dependent holoenzyme TglHI. Additionally, it highlights the evolutionary and structural conservation in the DUF692 family of biosynthetic enzymes that produce diverse RiPPs.
结构多样的天然产物，如核糖体合成和翻译后修饰的肽（RiPPs），显示出广泛的生物活性。目前，3-硫代谷氨酸（3-thiaGlu）生物合成过程中一个不常见反应步骤的机制还不太清楚。由 TglHI 全酶催化的 TglA-Cys 肽中 Cys 上的β-碳的去除仍然难以捉摸。在这里，我们展示了 TglHI 复合物与结合铁和不结合铁的三种晶体结构，揭示了催化口袋是由 TglH-TglI 的相互作用形成的，其激活是构象依赖性的。生化分析表明活性簇中至少需要两个铁离子，我们确定了第三个铁位的位置。总的来说，我们的研究提供了对非血红素依赖的双氧酶全酶 TglHI 的激活和催化机制的深入了解。此外，它还突出了产生各种 RiPP 的生物合成酶的 DUF692 家族在进化和结构上的保守性。
