Laboratory of Structural Chemistry and Biology, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary.
Hevesy György PhD School of Chemistry, Institute of Chemistry, Eötvös Loránd University, Pázmány Péter sétány 1/A, H-1117 Budapest, Hungary.
Molecules. 2023 Jul 26;28(15):5655. doi: 10.3390/molecules28155655.
Myostatin, an important negative regulator of muscle mass, is a therapeutic target for muscle atrophic disorders such as muscular dystrophy. Thus, the inhibition of myostatin presents a strategy to treat these disorders. It has long been established that the myostatin prodomain is a strong inhibitor of the mature myostatin, and the minimum peptide of the prodomain-corresponding to the α-helix of its lasso-region-responsible for the inhibitory efficiency was defined and characterized as well. Here we show that the minimum peptide segment based on the growth differentiation factor 11 (GDF11), which we found to be more helical in its stand-alone solvated stfate than the similar segment of myostatin, is a promising new base scaffold for inhibitor design. The proposed inhibitory peptides in their solvated state and in complex with the mature myostatin were analyzed by in silico molecule modeling supplemented with the electronic circular dichroism spectroscopy measurements. We defined the Gaussian-Mahalanobis mean score to measure the fraction of dihedral angle-pairs close to the desired helical region of the Ramachandran-plot, carried out RING analysis of the peptide-protein interaction networks and characterized the internal motions of the complexes using our rigid-body segmentation protocol. We identified a variant-11m2-that is sufficiently ordered both in solvent and within the inhibitory complex, forms a high number of contacts with the binding-pocket and induces such changes in its internal dynamics that lead to a rigidified, permanently locked conformation that traps this peptide in the binding site. We also showed that the naturally evolved α-helix has been optimized to simultaneously fulfill two very different roles: to function as a strong binder as well as a good leaving group. It forms an outstanding number of non-covalent interactions with the mature core of myostatin and maintains the most ordered conformation within the complex, while it induces independent movement of the gate-keeper β-hairpin segment assisting the dissociation and also results in the least-ordered solvated form which provides extra stability for the dissociated state and discourages rebinding.
肌肉生长抑制素（Myostatin）是肌肉质量的重要负调控因子，是肌肉萎缩性疾病（如肌肉营养不良症）的治疗靶点。因此，抑制肌肉生长抑制素是治疗这些疾病的一种策略。长期以来，人们一直认为肌肉生长抑制素前肽是成熟肌肉生长抑制素的强抑制剂，并且已经确定并表征了前肽对应的最小肽（对应于其套索区域的α-螺旋，负责抑制效率）。在这里，我们展示了基于生长分化因子 11（GDF11）的最小肽段，我们发现它在其独立的溶剂化状态下比肌肉生长抑制素的类似肽段更具螺旋性，是一种很有前途的新抑制剂设计基础支架。通过计算机分子建模并辅以电子圆二色性光谱测量，对溶剂化状态下和与成熟肌肉生长抑制素复合的拟议抑制肽进行了分析。我们定义了高斯-马哈拉诺比斯均值得分来测量接近拉曼查兰图中所需螺旋区域的二面角对分数，进行了肽-蛋白相互作用网络的 RING 分析，并使用我们的刚体分割协议对复合物的内部运动进行了表征。我们鉴定了变体 11m2-它在溶剂中和抑制复合物中都具有足够的有序性，与结合口袋形成大量接触，并诱导其内部动力学发生变化，从而导致僵化、永久性锁定构象，将该肽锁定在结合位点中。我们还表明，天然进化的α-螺旋已被优化为同时发挥两个非常不同的作用：作为强结合物以及良好的离去基团。它与成熟的肌肉生长抑制素核心形成了大量的非共价相互作用，并在复合物中保持最有序的构象，同时诱导门控β发夹段的独立运动，辅助解离，并且还导致最无序的溶剂化形式，为解离状态提供额外的稳定性，并阻止重新结合。
