Department of Molecular and Cell Biology, University of Connecticut, Storrs, CT, United States.
Social Profit Network, Menlo Park, CA, United States.
Elife. 2022 Aug 1;11:e75531. doi: 10.7554/eLife.75531.
Mitochondria play a central role in metabolic homeostasis, and dysfunction of this organelle underpins the etiology of many heritable and aging-related diseases. Tetrapeptides with alternating cationic and aromatic residues such as SS-31 (elamipretide) show promise as therapeutic compounds for mitochondrial disorders. In this study, we conducted a quantitative structure-activity analysis of three alternative tetrapeptide analogs, benchmarked against SS-31, that differ with respect to aromatic side chain composition and sequence register. We present the first structural models for this class of compounds, obtained with Nuclear Magnetic Resonance (NMR) and molecular dynamics approaches, showing that all analogs except for SS-31 form compact reverse turn conformations in the membrane-bound state. All peptide analogs bound cardiolipin-containing membranes, yet they had significant differences in equilibrium binding behavior and membrane interactions. Notably, analogs had markedly different effects on membrane surface charge, supporting a mechanism in which modulation of membrane electrostatics is a key feature of their mechanism of action. The peptides had no strict requirement for side chain composition or sequence register to permeate cells and target mitochondria in mammalian cell culture assays. All four peptides were pharmacologically active in serum withdrawal cell stress models yet showed significant differences in their abilities to restore mitochondrial membrane potential, preserve ATP content, and promote cell survival. Within our peptide set, the analog containing tryptophan side chains, SPN10, had the strongest impact on most membrane properties and showed greatest efficacy in cell culture studies. Taken together, these results show that side chain composition and register influence the activity of these mitochondria-targeted peptides, helping provide a framework for the rational design of next-generation therapeutics with enhanced potency.
线粒体在代谢稳态中起着核心作用，该细胞器的功能障碍是许多遗传性和与衰老相关疾病的病因。具有交替正电荷和芳香残基的四肽，如 SS-31（elamipretide），作为治疗线粒体疾病的治疗化合物具有广阔的前景。在这项研究中，我们对三种替代四肽类似物进行了定量构效关系分析，以 SS-31 为基准，这些类似物在芳香侧链组成和序列登记方面存在差异。我们首次提出了该类化合物的结构模型，通过核磁共振（NMR）和分子动力学方法获得，表明除 SS-31 外，所有类似物在膜结合状态下均形成紧凑的反向转折构象。所有肽类似物都结合含有心磷脂的膜，但它们在平衡结合行为和膜相互作用方面存在显著差异。值得注意的是，类似物对膜表面电荷有明显不同的影响，支持一种机制，即调节膜静电是其作用机制的关键特征。这些肽没有严格要求侧链组成或序列登记即可穿透细胞，并在哺乳动物细胞培养试验中靶向线粒体。在血清去除细胞应激模型中，所有四种肽都具有药理活性，但在恢复线粒体膜电位、保持 ATP 含量和促进细胞存活的能力方面存在显著差异。在我们的肽组中，含有色氨酸侧链的类似物 SPN10 对大多数膜特性的影响最强，在细胞培养研究中表现出最强的功效。总之，这些结果表明侧链组成和登记影响这些靶向线粒体的肽的活性，有助于为具有增强效力的下一代治疗剂的合理设计提供框架。
