Structure-based Design of Prefusion-stabilized SARS-CoV-2 Spikes

Ching-Lin Hsieh, Jory A. Goldsmith, Jeffrey M. Schaub, Andrea M. DiVenere, Hung-Che Kuo, Kamyab Javanmardi, Kevin C. Le, Daniel Wrapp, Alison Gene-Wei Lee, Yutong Liu, Chia-Wei Chou, Patrick O. Byrne, Christy K. Hjorth, Nicole V. Johnson, John Ludes-Meyers, Annalee W. Nguyen, Juyeon Park, Nianshuang Wang, Dzifa Amengor, Jason J. Lavinder, Gregory C. Ippolito, Jennifer A. Maynard†, Ilya J. Finkelstein† & Jason S. McLellan† († co-corresponding), Science :eabd0826 (2020).
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The COVID-19 pandemic has led to accelerated efforts to develop therapeutics and vaccines. A key target of these efforts is the spike (S) protein, which is metastable and difficult to produce recombinantly. Here, we characterized 100 structure-guided spike designs and identified 26 individual substitutions that increased protein yields and stability. Testing combinations of beneficial substitutions resulted in the identification of HexaPro, a variant with six beneficial proline substitutions exhibiting ~10-fold higher expression than its parental construct and the ability to withstand heat stress, storage at room temperature, and three freeze-thaw cycles. A 3.2 Å-resolution cryo-EM structure of HexaPro confirmed that it retains the prefusion spike conformation. High-yield production of a stabilized prefusion spike protein will accelerate the development of vaccines and serological diagnostics for SARS-CoV-2.