Wang Jiaqi, Guo Ming, Dai Shuyan, Wei Hudie
Department of Oncology, NHC Key Laboratory of Cancer Proteomics & State Local Joint Engineering Laboratory for Anticancer Drugs, National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, Hunan 410008, China.
Department of Pharmacology, Xiangya School of Pharmaceutical Sciences, Central South University, Changsha, Hunan 410078, China.
iScience. 2025 Aug 6;28(9):113309. doi: 10.1016/j.isci.2025.113309. eCollection 2025 Sep 19.
BH3 mimetics targeting the BCL-2 family hold broad promise for cancer therapy. High similarity between the anti-apoptotic proteins BCL-XL and BCL-2 challenges the engineering of selective inhibitors. The BH3-only protein HRK is a natural selective inhibitor of BCL-XL and to a less extent of BCL-2. The detailed interaction mechanism remains elusive. Our structural and mutational analyses show that the discrepant conformational changes and non-conserved residues in the α2-α3 region are crucial for the preferential binding between BCL-XL and HRK. BCL-XL tolerates hydrophilic Thr33 or hydrophobic substitutions at the h1 position of HRK, whereas BCL-2 favors hydrophobic interactions, resulting in a weaker affinity for HRK. In addition, we design HRK-derived stapled peptides with improved helicity and activity against BCL-XL and BCL-2, and further elucidate the structural mechanism. Our findings reveal the binding specificity of HRK interactions with BCL-XL and BCL-2, and provide advanced insights into the development of BH3 mimetics.
靶向BCL-2家族的BH3模拟物在癌症治疗方面具有广阔前景。抗凋亡蛋白BCL-XL和BCL-2之间的高度相似性对选择性抑制剂的设计构成挑战。仅含BH3结构域的蛋白HRK是BCL-XL的天然选择性抑制剂，对BCL-2的抑制作用较弱。其详细的相互作用机制仍不清楚。我们的结构和突变分析表明，α2-α3区域中不同的构象变化和非保守残基对于BCL-XL与HRK之间的优先结合至关重要。BCL-XL能够耐受HRK的h1位置上的亲水性苏氨酸33或疏水性取代，而BCL-2则倾向于疏水相互作用，导致其对HRK的亲和力较弱。此外，我们设计了具有更高螺旋度和对BCL-XL及BCL-2活性的HRK衍生的订书肽，并进一步阐明了其结构机制。我们的研究结果揭示了HRK与BCL-XL和BCL-2相互作用的结合特异性，并为BH3模拟物的开发提供了深入见解。
