Anti-apoptotic BCL-2 regulation by changes in dynamics of its long unstructured loop

• Published in: Communications biology Vol. 3; no. 1; p. 668
• Main Authors: Lan, Yu-Jing, Yeh, Pei-Shan, Kao, Te-Yu, Lo, Yuan-Chao, Sue, Shih-Che, Chen, Yu-Wen, Hwang, Dennis W., Chiang, Yun-Wei
• Format: Journal Article
• Language: English
• Published: London Nature Publishing Group UK 12.11.2020; Nature Publishing Group
• Subjects: 101/6; 631/45/535; 631/57/2269; 631/92/56; 82/29; 82/80; 82/83; Affinity; Allosteric properties; Allosteric Regulation - genetics; Apoptosis; Bcl-2 protein; Biology; Biomedical and Life Sciences; Bridged Bicyclo Compounds, Heterocyclic - pharmacology; Flexibility; Humans; Life Sciences; Ligands; Magnetic resonance spectroscopy; Molecular Dynamics Simulation; Mutation; NMR; Nuclear magnetic resonance; Phosphorylation; Protein Domains; Protein structure; Proteins; Proto-Oncogene Proteins c-bcl-2 - chemistry; Proto-Oncogene Proteins c-bcl-2 - genetics; Proto-Oncogene Proteins c-bcl-2 - metabolism; Recombinant Proteins - chemistry; Recombinant Proteins - genetics; Recombinant Proteins - metabolism; Sulfonamides - pharmacology
• ISSN: 2399-3642; 2399-3642
• DOI: 10.1038/s42003-020-01390-6

BCL-2, a key protein in inhibiting apoptosis, has a 65-residue-long highly flexible loop domain (FLD) located on the opposite side of its ligand-binding groove. In vivo phosphorylation of the FLD enhances the affinity of BCL-2 for pro-apoptotic ligands, and consequently anti-apoptotic activity. However, it remains unknown as to how the faraway, unstructured FLD modulates the affinity. Here we investigate the protein-ligand interactions by fluorescence techniques and monitor protein dynamics by DEER and NMR spectroscopy tools. We show that phosphomimetic mutations on the FLD lead to a reduction in structural flexibility, hence promoting ligand access to the groove. The bound pro-apoptotic ligands can be displaced by the BCL-2-selective inhibitor ABT-199 efficiently, and thus released to trigger apoptosis. We show that changes in structural flexibility on an unstructured loop can activate an allosteric protein that is otherwise structurally inactive. Lan et al. make single and triple phosphomimetic mutations in a long flexible loop domain of BCL-2 and show that these mutations reduce structural flexibility and promote ligand access to the groove. Their study indicates that changes in structural flexibility on an unstructured loop can activate an allosteric, otherwise inactive protein.