Chimeric protein probes for C5a receptors through fusion of the anaphylatoxin C5a core region with a small-molecule antagonist  

作　　者：Chao Zuo Wei-Wei Shi Xiao-Xu Chen Marie Glatz Bernd Riedl Ingo Flamme Elisabeth Pook Jiawei Wang Ge-Min Fang Donald Bierer Lei Liu 

机构地区：[1]Tsinghua-Peking Center for Life Sciences,Ministry of Education Key Laboratory of Bioorganic Phosphorus Chemistry and Chemical Biology,Center for Synthetic and Systems Biology,Department of Chemistry,Tsinghua University,Beijing 100084,China [2]School of Life Science,Institutes of Physical Science and Information Technology,Anhui University,Hefei 230601,China [3]Bayer AG,Department of Medicinal Chemistry,Aprather Weg 18A,42096 Wuppertal,Germany [4]Bayer AG,Cardiovascular Research,42096 Wuppertal,Germany [5]Bayer AG,Lead Discovery,42096 Wuppertal,Germany

出　　处：《Science China Chemistry》2019年第10期1371-1378,共8页中国科学（化学英文版）

基　　金：supported by the National Key R&D Program of China (2017YFA0505200);the National Natural Science Foundation of China (21532004, 91753205, 81621002, 21621003)

摘　　要：Blockade of the interaction of anaphylatoxin C5a with its receptor C5aR1 has been actively studied as a potential treatment for many inflammatory diseases;but current C5a antagonists exhibit inadequate potency and poor species cross-reactivity, and novel biochemical tools are needed to investigate whether the core region of C5a contains important interaction epitopes that can explain these limitations. Herein, we report the development of chimeric protein C5a probes containing both the complete core region of rat or human C5a, and the small-molecule antagonist PMX53-1. These probes were chemically synthesized through hydrazide-based native chemical ligation of a linear peptide hydrazide with the requisite cyclopeptidic antagonist, both of which were made by solid-phase synthesis. Quasi-racemic X-ray crystallography established that attachment of PMX53-1 did not affect the structure of the core region of C5a. Subsequent C5aR1 activity assays demonstrated the probes can provide valuable insights into the development of C5a antagonists;for example, they exhibited significantly better binding affinity and much improved species cross-reactivity than PMX53-1, supporting the notion that the effect of some epitopes outside the C-terminus of C5a should be taken into consideration when designing better C5a antagonists. Surprisingly, the core region of C5a was found to partially agonize C5aR1, suggesting the presence of more than one agonistic interaction in the binding of C5a to C5aR1. This study exemplifies the value of chemical protein synthesis in developing novel receptor probes for drug discovery research.Blockade of the interaction of anaphylatoxin C5a with its receptor C5aR1 has been actively studied as a potential treatment for many inflammatory diseases; but current C5a antagonists exhibit inadequate potency and poor species cross-reactivity, and novel biochemical tools are needed to investigate whether the core region of C5a contains important interaction epitopes that can explain these limitations. Herein, we report the development of chimeric protein C5a probes containing both the complete core region of rat or human C5a, and the small-molecule antagonist PMX53-1. These probes were chemically synthesized through hydrazide-based native chemical ligation of a linear peptide hydrazide with the requisite cyclopeptidic antagonist, both of which were made by solid-phase synthesis. Quasi-racemic X-ray crystallography established that attachment of PMX53-1 did not affect the structure of the core region of C5a. Subsequent C5aR1 activity assays demonstrated the probes can provide valuable insights into the development of C5a antagonists; for example, they exhibited significantly better binding affinity and much improved species cross-reactivity than PMX53-1, supporting the notion that the effect of some epitopes outside the C-terminus of C5a should be taken into consideration when designing better C5a antagonists. Surprisingly, the core region of C5a was found to partially agonize C5aR1, suggesting the presence of more than one agonistic interaction in the binding of C5a to C5aR1. This study exemplifies the value of chemical protein synthesis in developing novel receptor probes for drug discovery research.

关 键 词：ANAPHYLATOXIN C5A PMX53 quasi-racemic X-ray CRYSTALLOGRAPHY native chemical LIGATION 

分 类 号：O62[理学—有机化学]