Transforming growth factor‐β1 (TGF‐β1) signaling pathway has been implicated in the fibroblast activation of hypertrophic scarring (HS). Previously, we proposed a new biotherapeutic strategy to combat HS by disrupting the intermolecular interaction of TGF‐β1 with its cognate type‐II receptor (TβR‐II). Here, we further demonstrate that the binding site of TGF‐β1 to TβR‐II is not overlapped with the conformational wrist epitope and linear knuckle epitope that are traditionally recognized as the functional binding sites of bone morphogenetic protein‐2 (BMP‐2) to its type‐II receptor (BMPR‐II), which can thus be regarded as a new functional site we called elbow epitope. Structural, energetic, and dynamic investigations reveal that the elbow epitope consists of two sequentially discontinuous, spatially vicinal segments Loop^30‐34 and Turn^90‐95; they cannot work effectively to independently interact with TβR‐II. Rational redesign of the epitope is performed using an integrated in silio‐in vitro method based on crystal and modeled structure data. In the procedure, the two epitope segments are split from the interface of TGF‐β1‐TβR‐II complex and then connected with each other in a head‐to‐tail manner by adding a flexible poly‐(Gly)n linker between them, thus resulting in a series of combined peptides. We found that the peptide affinity reaches maximum at n = 2, which shares a consistent binding mode with the elbow epitope at native complex interface. The linker of either too long (n > 2) or too short (n < 2) cannot properly place the gap space between the two segments, thus impairing the binding compatibility of designed peptides with TβR‐II active site.

中文翻译：

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基于结构的发现和重新设计在肥厚性瘢痕生物治疗中通过其 II 型受体识别 TGF-β1 肘表位

转化生长因子-β1 (TGF-β1) 信号通路与肥厚性瘢痕 (HS) 的成纤维细胞活化有关。此前，我们提出了一种新的生物治疗策略，通过破坏 TGF-β1 与其同源 II 型受体 (TβR-II) 的分子间相互作用来对抗 HS。在这里，我们进一步证明 TGF-β1 与 TβR-II 的结合位点不与传统上被认为是骨形态发生蛋白-2 (BMP-2) 的功能结合位点的构象腕表位和线性关节表位重叠其II型受体（BMPR-II），因此可以被视为我们称为肘表位的新功能位点。结构、能量和动态研究表明，肘部表位由两个顺序不连续的空间相邻片段环^30-34和转弯^90-95组成；它们无法有效地独立与 TβR-II 相互作用。使用基于晶体和模型结构数据的体外集成方法对表位进行合理的重新设计。在此过程中，两个表位片段从 TGF-β1-TβR-II 复合物的界面分离，然后通过在它们之间添加一个灵活的 poly-(Gly) n接头以头尾方式相互连接，从而产生一系列组合肽。我们发现肽亲和力在 n = 2 时达到最大值，这与肘部具有一致的结合模式天然复合物界面的表位。太长 (n > 2) 或太短 (n < 2) 的接头无法正确放置两个片段之间的间隙空间，从而削弱设计肽与 TβR-II 活性位点的结合相容性。