School of Life Science and Technology, ShanghaiTech University, Shanghai, China.
Department of Physiology, Anatomy and Genetics, University of Oxford, Oxford, UK.
Nat Plants. 2024 Jun;10(6):880-889. doi: 10.1038/s41477-024-01697-w. Epub 2024 May 13.
In plants, the rapid accumulation of proline is a common response to combat abiotic stress. Delta-1-pyrroline-5-carboxylate synthase (P5CS) is a rate-limiting enzyme in proline synthesis, catalysing the initial two-step conversion from glutamate to proline. Here we determine the first structure of plant P5CS. Our results show that Arabidopsis thaliana P5CS1 (AtP5CS1) and P5CS2 (AtP5CS2) can form enzymatic filaments in a substrate-sensitive manner. The destruction of AtP5CS filaments by mutagenesis leads to a significant reduction in enzymatic activity. Furthermore, separate activity tests on two domains reveal that filament-based substrate channelling is essential for maintaining the high catalytic efficiency of AtP5CS. Our study demonstrates the unique mechanism for the efficient catalysis of AtP5CS, shedding light on the intricate mechanisms underlying plant proline metabolism and stress response.
在植物中，脯氨酸的快速积累是一种常见的应对非生物胁迫的反应。δ-1-吡咯啉-5-羧酸合成酶（P5CS）是脯氨酸合成中的限速酶，催化从谷氨酸到脯氨酸的初始两步转化。在这里，我们确定了植物 P5CS 的第一个结构。我们的结果表明，拟南芥 P5CS1（AtP5CS1）和 P5CS2（AtP5CS2）可以以底物敏感的方式形成酶丝。通过突变破坏 AtP5CS 丝会导致酶活性显著降低。此外，对两个结构域的单独活性测试表明，基于丝的底物通道对于维持 AtP5CS 的高催化效率是必不可少的。我们的研究证明了 AtP5CS 高效催化的独特机制，为植物脯氨酸代谢和应激反应的复杂机制提供了线索。
