Department of Chemistry and Chemical Biology, Cornell University, Ithaca, NY, 14853, USA.
Department of Molecular Medicine, Cornell University, Ithaca, NY, 14853, USA.
Nat Commun. 2024 Mar 4;15(1):1971. doi: 10.1038/s41467-024-46351-3.
The glutaminase enzymes GAC and GLS2 catalyze the hydrolysis of glutamine to glutamate, satisfying the 'glutamine addiction' of cancer cells. They are the targets of anti-cancer drugs; however, their mechanisms of activation and catalytic activity have been unclear. Here we demonstrate that the ability of GAC and GLS2 to form filaments is directly coupled to their catalytic activity and present their cryo-EM structures which provide a view of the conformational states essential for catalysis. Filament formation guides an 'activation loop' to assume a specific conformation that works together with a 'lid' to close over the active site and position glutamine for nucleophilic attack by an essential serine. Our findings highlight how ankyrin repeats on GLS2 regulate enzymatic activity, while allosteric activators stabilize, and clinically relevant inhibitors block, filament formation that enables glutaminases to catalyze glutaminolysis and support cancer progression.
谷氨酰胺酶 GAC 和 GLS2 催化谷氨酰胺水解为谷氨酸，满足癌细胞的“谷氨酰胺成瘾”。它们是抗癌药物的靶点；然而，其激活机制和催化活性尚不清楚。在这里，我们证明 GAC 和 GLS2 形成纤维的能力与其催化活性直接相关，并展示了它们的冷冻电镜结构，为催化所需的构象状态提供了一个视图。纤维形成指导“激活环”采用特定构象，与“盖子”一起作用以封闭活性位点并将谷氨酰胺定位为受关键丝氨酸的亲核攻击。我们的发现强调了锚蛋白重复序列如何调节 GLS2 的酶活性，而别构激活剂稳定，临床相关抑制剂阻止纤维形成，使谷氨酰胺酶能够催化谷氨酰胺分解代谢并支持癌症进展。
