Department of Obstetrics and Gynecology, Yidu Central Hospital Affiliated to Weifang Medical University, Weifang 262500, China.
Department of Obstetrics and Gynecology, Yidu Central Hospital Affiliated to Weifang Medical University, Weifang 262500, China.
Biophys Chem. 2021 Sep;276:106625. doi: 10.1016/j.bpc.2021.106625. Epub 2021 May 23.
Human epidermal growth factor receptor 2 (HER2) has been established as an approved druggable target for the treatment of patients with diverse gynecological tumors such as ovarian, cervical and breast cancers. The mitogen-inducible gene 6 (MIG6) protein is a negative regulator of HER2 signaling by using its Seg1 segment to disrupt the allosteric dimerization of HER2 kinase domain. Previous studies found that the Seg1 adopts three separated hotspots to interact with the HER2 dimerization interface, in which the third hotspot (H3) is located at the core region of the interface but its derived H3 peptide (PKYVS) and Tyr358Phe mutant (PKFVS) cannot bind effectively to the interface in an independent manner. In this study, we demonstrate that the H3 peptide can be converted from nonbinder to a moderate binder of HER2 by just adding an orthogonal noncovalent interaction system (X⋯O┄H) between a halogen bond (X⋯O) and a hydrogen bond (H┄O) involving peptide Phe358 residue and HER2 Val948/Trp951 residues. High-level calculations are utilized to rigorously characterize and rationally design the X⋯O┄H system, which is then optimized with different halogen atoms and at different substituting positions. It is revealed that there is a synergistic effect between the X⋯O and H┄O of the orthogonal interaction system; formation of the halogen bond can enhance the interaction strength of the hydrogen bond. In silico analysis and in vitro assay reach a consistence that Br-substitution at the m-position of peptide Phe358 phenyl moiety is the best choice that can render strong interaction for the X⋯O┄H system, which also makes the peptide 'bindable' to HER2 kinase domain, while F/Cl/I-substitution at the same position can only improve the peptide affinity moderately or modestly. In contrast, the Br-substitution at the o- and p-positions of peptide Phe358 phenyl moiety cannot define effective X⋯O┄H interaction and thus does not confer additional affinity to the HER2-peptide complex.
人类表皮生长因子受体 2（HER2）已被确定为治疗多种妇科肿瘤（如卵巢癌、宫颈癌和乳腺癌）的一种可用药靶。有丝分裂原诱导基因 6（MIG6）蛋白通过其 Seg1 片段干扰 HER2 激酶结构域的变构二聚化，从而成为 HER2 信号的负调节剂。先前的研究发现，Seg1 采用三个分离的热点与 HER2 二聚化界面相互作用，其中第三个热点（H3）位于界面的核心区域，但衍生的 H3 肽（PKYVS）和 Tyr358Phe 突变体（PKFVS）不能独立有效地与界面结合。在这项研究中，我们证明了 H3 肽可以通过在涉及肽 Phe358 残基和 HER2 Val948/Trp951 残基的氢键（H┄O）和卤键（X⋯O）之间添加正交非共价相互作用系统（X⋯O┄H），从非结合物转变为 HER2 的中等结合物。利用高精度计算严格表征和合理设计 X⋯O┄H 系统，然后使用不同的卤原子和不同的取代位置对其进行优化。结果表明，正交相互作用系统的 X⋯O 和 H┄O 之间存在协同效应；卤键的形成可以增强氢键的相互作用强度。计算机分析和体外测定结果一致表明，在肽 Phe358 苯环的 m 位取代 Br 是最佳选择，可以为 X⋯O┄H 系统提供强相互作用，这也使该肽能够“与 HER2 激酶结构域结合”，而在相同位置取代 F/Cl/I 只能适度或适度提高肽的亲和力。相比之下，肽 Phe358 苯环的 o-和 p-位取代 Br 不能确定有效的 X⋯O┄H 相互作用，因此不会为 HER2-肽复合物赋予额外的亲和力。
