An Min, Cheng Xin, Zhang Yu, Gu Jiang, Mao Xuhu
Department of Clinical Microbiology and Immunology, College of Pharmacy and Medical Laboratory, Army Medical University (Third Military Medical University), Chongqing 400038, China.
Department of Biochemistry and Molecular Biology, School of Basic Medicine, Army Medical University (Third Military Medical University), Chongqing 400038, China.
Toxins (Basel). 2025 May 7;17(5):232. doi: 10.3390/toxins17050232.
lethal factor 1 (BLF1), a toxin derived from , reacts with eukaryotic initiation factor (eIF) 4A to inhibit protein synthesis. eIF4A1 and eIF4A2 are involved in translation initiation and share over 90% sequence similarity. However, they exert distinct effects on cancer treatment outcomes. To understand the molecular mechanism by which BLF1 modulates eIF4A isoforms in cancer cells, we investigated its effects on eIF4A-mediated adenosine 5'-triphosphate (ATP) hydrolysis. We found that eIF4A1 has a higher ATP-binding affinity compared to eIF4A2 (K = 6.55 ± 0.78 μM vs. K = 11.61 ± 2.33 μM). Meanwhile, we also found that eIF4A1 is more sensitive to changes in temperature, pH, and Mg concentration. Through N-terminal swapping and single amino acid mutations, we found that leucine 98 (L98) and alanine 100 (A100) play important roles in the ATPase activities of eIF4A isoforms. Moreover, BLF1 treatment significantly enhanced eIF4A2-mediated ATP hydrolysis at all tested ATP concentrations. These differences in BLF1-regulated eIF4A isoforms may explain its selective cytotoxicity against cancer cells. Our findings provide molecular insights into the functional difference between eIF4A isoforms and suggest that BLF1 might be of promising value for anticancer therapies.
致死因子1（BLF1）是一种源自[具体来源未给出]的毒素，它与真核起始因子（eIF）4A反应以抑制蛋白质合成。eIF4A1和eIF4A2参与翻译起始，并且序列相似性超过90%。然而，它们对癌症治疗结果产生不同的影响。为了理解BLF1在癌细胞中调节eIF4A异构体的分子机制，我们研究了它对eIF4A介导的腺苷5'-三磷酸（ATP）水解的影响。我们发现，与eIF4A2相比，eIF4A1具有更高的ATP结合亲和力（K = 6.55 ± 0.78 μM对K = 11.61 ± 2.33 μM）。同时，我们还发现eIF4A1对温度、pH和镁浓度的变化更敏感。通过N端交换和单氨基酸突变，我们发现亮氨酸98（L98）和丙氨酸100（A100）在eIF4A异构体的ATP酶活性中起重要作用。此外，在所有测试的ATP浓度下，BLF1处理均显著增强了eIF4A2介导的ATP水解。BLF1调节的eIF4A异构体的这些差异可能解释了其对癌细胞的选择性细胞毒性。我们的发现为eIF4A异构体之间的功能差异提供了分子见解，并表明BLF1可能在抗癌治疗中具有有前景的价值。
