%A Bhavesh Khatri %A Ishika Pramanick %A Sameer Kumar Malladi %A Raju S Rajmani %A Sahil Kumar %A Pritha Ghosh %A Nayanika Sengupta %A R Rahisuddin %A Narender Kumar %A S Kumaran %A Rajesh P Ringe %A Raghavan Varadarajan %A Somnath Dutta %A Jayanta Chatterjee %O The copyright of this article belongs to Nature %J Nature Chemical Biology %T A dimeric proteomimetic prevents SARS-CoV-2 infection by dimerizing the spike protein %X Protein tertiary structure mimetics are valuable tools to target large protein-protein interaction interfaces. Here, we demonstrate a strategy for designing dimeric helix-hairpin motifs from a previously reported three-helix-bundle miniprotein that targets the receptor-binding domain (RBD) of severe acute respiratory syndrome-coronavirus-2 (SARS-CoV-2). Through truncation of the third helix and optimization of the interhelical loop residues of the miniprotein, we developed a thermostable dimeric helix-hairpin. The dimeric four-helix bundle competes with the human angiotensin-converting enzyme 2 (ACE2) in binding to RBD with 2:2 stoichiometry. Cryogenic-electron microscopy revealed the formation of dimeric spike ectodomain trimer by the four-helix bundle, where all the three RBDs from either spike protein are attached head-to-head in an open conformation, revealing a novel mechanism for virus neutralization. The proteomimetic protects hamsters from high dose viral challenge with replicative SARS-CoV-2 viruses, demonstrating the promise of this class of peptides that inhibit protein-protein interaction through target dimerization. %D 2022 %I NATURE %L open2981