利用I-Mutant2.0辅助设计与优化中东呼吸综合征冠状病毒融合抑制多肽

Ⅰ型膜融合蛋白(class I membrane fusion protein)在Ⅰ型包膜病毒入侵宿主细胞过程中发挥重要作用。基于抑制六螺旋结构形成的多肽类融合抑制剂设计的原理是模拟该蛋白融合区域的自身序列,与病毒融合蛋白结合形成异源六聚体,从而阻断病毒与靶细胞膜的融合。此类融合抑制剂的传统设计主要基于一级与二级结构,但为进一步强化其抗病毒活性,通常需依赖病毒膜融合蛋白三级结构信息,从而限制了对那些尚无病毒蛋白三级结构信息的新发病毒的多肽类融合抑制剂的快速优化和研发。本研究提出了不依赖蛋白三级结构信息,而利用I-Mutant2.0软件来辅助设计和优化多肽类病毒膜融合抑制剂的设想。根据I-Mutant2.0的预测结果,以中东呼吸综合征冠状病毒(Middle East respiratory syndrome coronavirus,MERS-CoV)为模型,分析该病毒HR2区融合抑制剂序列中若干适合与不适合优化的位点,并设计了一系列多肽。结果发现,对适合优化的位点进行调整的多肽,其对HR1的结合能力及对病毒的抑制活性均有所提升;反之,多肽活性明显下降。结果表明,利用I-Mutant2.0辅助设计与优化病毒融合抑制多肽的方法具有一定的可行性,为进一步开发新的融合抑制剂设计方法奠定了基础。

Using I-Mutant2.0 to assist the design and optimization of MERS-CoV fusion inhibitory peptides

Class I membrane fusion protein plays an important role in the entry of class I enveloped viruses. Peptide virus fusion inhibitors targeting the six-helix bundle structure of viral fusion protein were designed by mimicking partial sequence of the viral fusion protein. The peptides can interact with the viral fusion protein to form heterogeneous complexes, thus inhibiting the fusion between virus envelope and cell membrane. In classical approaches, the viral fusion inhibitors are designed mainly based on the primary and secondary structural information of fusion protein. However, to improve the antiviral activity, peptides should be optimized based on the tertiary structure of fusion protein. This may limit the rapid development of fusion inhibitors against emerging viruses because the tertiary structure information of these viral proteins is generally unavailable yet. In this study, we proposed to design and optimize viral fusion inhibitors based on the primary sequence, rather than the tertiary structure of the viral fusion protein using I-Mutant2.0 computer program. Using this program, several compatible and incompatible optimization sites in the sequence of a Middle East respiratory syndrome coronavirus (MERS-CoV) fusion inhibitory peptide were identified. Based on the analyzed results of MERS-CoV S protein HR2 region, several peptides with mutations in the compatible or incompatible optimization sites were designed and synthesized. It was found that modifications on compatible sites would significantly increase the inhibitory activity of the peptides, while modifications on incompatible sites resulted in decrease of the inhibitory activity of the peptides. The results confirmed the feasibility of this approach and laid the foundation for further development of novel virus fusion inhibitors.