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Cryo-EM structure of Human ACE2 bound to a high-affinity SARS CoV-2 mutantCryo-EM structure of Human ACE2 bound to a high-affinity SARS CoV-2 mutant
Structural highlights
FunctionACE2_HUMAN Carboxypeptidase which converts angiotensin I to angiotensin 1-9, a peptide of unknown function, and angiotensin II to angiotensin 1-7, a vasodilator. Also able to hydrolyze apelin-13 and dynorphin-13 with high efficiency. May be an important regulator of heart function. In case of human coronaviruses SARS and HCoV-NL63 infections, serve as functional receptor for the spike glycoprotein of both coronaviruses.[1] [2] [3] Publication Abstract from PubMedEmerging SARS-CoV-2 variants are creating major challenges in the ongoing COVID-19 pandemic. Being able to predict mutations that could arise in SARS-CoV-2 leading to increased transmissibility or immune evasion would be extremely valuable in development of broad-acting therapeutics and vaccines, and prioritising viral monitoring and containment. Here we use in vitro evolution to seek mutations in SARS-CoV-2 receptor binding domain (RBD) that would substantially increase binding to ACE2. We find a double mutation, S477N and Q498H, that increases affinity of RBD for ACE2 by 6.5-fold. This affinity gain is largely driven by the Q498H mutation. We determine the structure of the mutant-RBD:ACE2 complex by cryo-electron microscopy to reveal the mechanism for increased affinity. Addition of Q498H to SARS-CoV-2 RBD variants is found to boost binding affinity of the variants for human ACE2 and confer a new ability to bind rat ACE2 with high affinity. Surprisingly however, in the presence of the common N501Y mutation, Q498H inhibits binding, due to a clash between H498 and Y501 side chains. To achieve an intermolecular bonding network, affinity gain and cross-species binding similar to Q498H alone, RBD variants with the N501Y mutation must acquire instead the related Q498R mutation. Thus, SARS-CoV-2 RBD can access large affinity gains and cross-species binding via two alternative mutational routes involving Q498, with route selection determined by whether a variant already has the N501Y mutation. These mutations are now appearing in emerging SARS-CoV-2 variants where they have the potential to influence human-to-human and cross-species transmission. In vitro evolution predicts emerging SARS-CoV-2 mutations with high affinity for ACE2 and cross-species binding.,Bate N, Savva CG, Moody PCE, Brown EA, Evans SE, Ball JK, Schwabe JWR, Sale JE, Brindle NPJ PLoS Pathog. 2022 Jul 18;18(7):e1010733. doi: 10.1371/journal.ppat.1010733. , eCollection 2022 Jul. PMID:35849637[4] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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