State Key Laboratory of Cell Biology, Shanghai Institute of Biochemistry and Cell Biology, Center for Excellence in Molecular Cell Science, Chinese Academy of Sciences, University of Chinese Academy of Sciences, Shanghai, China.
Laboratory of Molecular Modeling, State Key Lab of Molecular Reaction Dynamics, Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, Liaoning, China.
Cell Res. 2023 Mar;33(3):245-257. doi: 10.1038/s41422-022-00773-0. Epub 2023 Jan 16.
Emerging evidence demonstrates that some metabolic enzymes that phosphorylate soluble metabolites can also phosphorylate a variety of protein substrates as protein kinases to regulate cell cycle, apoptosis and many other fundamental cellular processes. However, whether a metabolic enzyme dephosphorylates protein as a protein phosphatase remains unknown. Here we reveal the gluconeogenic enzyme fructose 1,6-biphosphatase 1 (FBP1) that catalyzes the hydrolysis of fructose 1,6-bisphosphate (F-1,6-BP) to fructose 6-phosphate (F-6-P) as a protein phosphatase by performing a high-throughput screening of metabolic phosphatases with molecular docking followed by molecular dynamics (MD) simulations. Moreover, we identify IκBα as the substrate of FBP1-mediated dephosphorylation by performing phosphoproteomic analysis. Mechanistically, FBP1 directly interacts with and dephosphorylates the serine (S) 32/36 of IκBα upon TNFα stimulation, thereby inhibiting NF-κB activation. MD simulations indicate that the catalytic mechanism of FBP1-mediated IκBα dephosphorylation is similar to F-1,6-BP dephosphorylation, except for higher energetic barriers for IκBα dephosphorylation. Functionally, FBP1-dependent NF-κB inactivation suppresses colorectal tumorigenesis by sensitizing tumor cells to inflammatory stresses and preventing the mobilization of myeloid-derived suppressor cells. Our finding reveals a previously unrecognized role of FBP1 as a protein phosphatase and establishes the critical role of FBP1-mediated IκBα dephosphorylation in colorectal tumorigenesis.
新出现的证据表明，一些磷酸化可溶性代谢物的代谢酶也可以作为蛋白激酶磷酸化各种蛋白底物，从而调节细胞周期、细胞凋亡和许多其他基本的细胞过程。然而，代谢酶是否作为蛋白磷酸酶使蛋白去磷酸化仍然未知。在这里，我们揭示了催化果糖 1,6-二磷酸（F-1,6-BP）水解为果糖 6-磷酸（F-6-P）的糖异生酶果糖 1,6-二磷酸酶 1（FBP1）是一种蛋白磷酸酶，方法是通过分子对接和分子动力学（MD）模拟对代谢磷酸酶进行高通量筛选。此外，我们通过磷酸蛋白质组学分析鉴定出 IκBα 是 FBP1 介导的去磷酸化的底物。从机制上讲，FBP1 在 TNFα 刺激下直接与 IκBα 的丝氨酸（S）32/36 相互作用并使其去磷酸化，从而抑制 NF-κB 的激活。MD 模拟表明，FBP1 介导的 IκBα 去磷酸化的催化机制与 F-1,6-BP 的去磷酸化相似，只是 IκBα 去磷酸化的能量障碍更高。在功能上，FBP1 依赖性 NF-κB 失活通过使肿瘤细胞对炎症应激敏感并防止髓系来源的抑制细胞的动员来抑制结直肠肿瘤发生。我们的发现揭示了 FBP1 作为蛋白磷酸酶的先前未被认识的作用，并确立了 FBP1 介导的 IκBα 去磷酸化在结直肠肿瘤发生中的关键作用。
