SARS-CoV-2 recruits a haem metabolite to evade antibody immunity

Annachiara Rosa, Valerie E Pye, Carl Graham, Luke Muir, Jeffrey Seow, Kevin W Ng, Nicola J Cook, Chloe Rees-Spear, Eleanor Parker, Mariana Silva Dos Santos, Carolina Rosadas, Alberto Susana, Hefin Rhys, Andrea Nans, Laura Masino, Chloe Roustan, Evangelos Christodoulou, Rachel Ulferts, Antoni Wrobel, Charlotte-Eve ShortMichael Fertleman, Rogier W Sanders, Judith Heaney, Moira Spyer, Svend Kjær, Andy Riddell, Michael H Malim, Rupert Beale, James I MacRae, Graham P Taylor, Eleni Nastouli, Marit J van Gils, Peter B Rosenthal, Massimo Pizzato, Myra O McClure, Richard S Tedder, George Kassiotis, Laura E McCoy, Katie J Doores, Peter Cherepanov

Research output: Contribution to journalArticlepeer-review

Abstract

The coronaviral spike is the dominant viral antigen and the target of neutralizing antibodies. We show that SARS-CoV-2 spike binds biliverdin and bilirubin, the tetrapyrrole products of haem metabolism, with nanomolar affinity. Using cryo-electron microscopy and X-ray crystallography we mapped the tetrapyrrole interaction pocket to a deep cleft on the spike N-terminal domain (NTD). At physiological concentrations, biliverdin significantly dampened the reactivity of SARS-CoV-2 spike with immune sera and inhibited a subset of neutralizing antibodies. Access to the tetrapyrrole-sensitive epitope is gated by a flexible loop on the distal face of the NTD. Accompanied by profound conformational changes in the NTD, antibody binding requires relocation of the gating loop, which folds into the cleft vacated by the metabolite. Our results indicate that the virus co-opts the haem metabolite for the evasion of humoral immunity via allosteric shielding of a sensitive epitope and demonstrate the remarkable structural plasticity of the NTD.

Original languageEnglish
JournalMedRxiv
DOIs
Publication statusPublished - 26 Jan 2021

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