Levdansky Yevgen, Deme Justin C, Turner David J, Piczak Claire T, Pekovic Filip, Valkov Anna L, Tarasov Sergey G, Lea Susan M, Valkov Eugene
National Cancer Institute, National Institutes of Health, Frederick, MD, USA.
Nat Commun. 2025 Jul 12;16(1):6452. doi: 10.1038/s41467-025-61194-2.
Legionella pneumophila, an intracellular bacterial pathogen, injects effector proteins into host cells to manipulate cellular processes and promote its survival and proliferation. Here, we reveal a unique mechanism by which the Legionella effector PieF perturbs host mRNA decay by targeting the human CCR4-NOT deadenylase complex. High-resolution cryo-electron microscopy structures and biochemical analyses reveal that PieF binds with nanomolar affinity to the NOT7 and NOT8 catalytic subunits of CCR4-NOT, obstructing RNA access and displacing a catalytic Mg²⁺ ion from the active site. Additionally, PieF prevents NOT7/8 from associating with their partner deadenylases NOT6/6L, inhibiting the assembly of a functional deadenylase complex. Consequently, PieF robustly blocks mRNA poly(A) tail shortening and degradation with striking potency and selectivity for NOT7/8. This inhibition of deadenylation by PieF impedes cell cycle progression in human cells, revealing a novel bacterial strategy to modulate host gene expression.
嗜肺军团菌是一种细胞内细菌病原体，它将效应蛋白注入宿主细胞以操纵细胞过程并促进其存活和增殖。在此，我们揭示了一种独特的机制，通过该机制军团菌效应蛋白PieF靶向人类CCR4-NOT去腺苷酸化酶复合体来干扰宿主mRNA降解。高分辨率冷冻电子显微镜结构和生化分析表明，PieF以纳摩尔亲和力与CCR4-NOT的NOT7和NOT8催化亚基结合，阻碍RNA进入并从活性位点置换催化性Mg²⁺离子。此外，PieF阻止NOT7/8与其伙伴去腺苷酸化酶NOT6/6L结合，抑制功能性去腺苷酸化酶复合体的组装。因此，PieF以显著的效力和对NOT7/8的选择性强力阻断mRNA聚（A）尾的缩短和降解。PieF对去腺苷酸化的这种抑制作用阻碍了人类细胞的细胞周期进程，揭示了一种调节宿主基因表达的新型细菌策略。
