title: A virus-binding hot spot on human angiotensin-converting enzyme 2 is critical for binding of two different coronaviruses.
abstract: How viruses evolve to select their receptor proteins for host cell entry is puzzling. We recently determined the crystal structures of NL63 coronavirus (NL63-CoV) and SARS coronavirus (SARS-CoV) receptor-binding domains (RBDs), each complexed with their common receptor, human angiotensin-converting enzyme 2 (hACE2), and proposed the existence of a virus-binding hot spot on hACE2. Here we investigated the function of this hypothetical hot spot using structure-guided biochemical and functional assays. The hot spot consists of a salt bridge surrounded by hydrophobic tunnel walls. Mutations that disturb the hot spot structure have significant effects on virus/receptor interactions, revealing critical energy contributions from the hot spot structure. The tunnel structure at the NL63-CoV/hACE2 interface is more compact than that at the SARS-CoV/hACE2 interface, and hence RBD/hACE2 binding affinities are decreased either by NL63-CoV mutations decreasing the tunnel space or by SARS-CoV mutations increasing the tunnel space. Furthermore, NL63-CoV RBD inhibits hACE2-dependent transduction by SARS-CoV spike protein, a successful application of the hot spot theory that has the potential to become a new antiviral strategy against SARS-CoV infections. These results suggest that the structural features of the hot spot on hACE2 were among the driving forces for the convergent evolution of NL63-CoV and SARS-CoV.
authors.affiliation: Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
authors.forename: Kailang
authors.initials: K
authors.lastname: Wu
authors.forename: Lang
authors.initials: L
authors.lastname: Chen
authors.forename: Guiqing
authors.initials: G
authors.lastname: Peng
authors.forename: Wenbo
authors.initials: W
authors.lastname: Zhou
authors.forename: Christopher A
authors.initials: CA
authors.lastname: Pennell
authors.forename: Louis M
authors.initials: LM
authors.lastname: Mansky
authors.forename: Robert J
authors.initials: RJ
authors.lastname: Geraghty
authors.forename: Fang
authors.initials: F
authors.lastname: Li
mesh_terms: D000085962:Angiotensin-Converting Enzyme 2; D058957:Coronavirus NL63, Human / Q000502:physiology*; D004252:DNA Mutational Analysis; D006801:Humans; D007703:Peptidyl-Dipeptidase A / Q000235:genetics / Q000378:metabolism*; D011485:Protein Binding; D011991:Receptors, Virus / Q000235:genetics / Q000378:metabolism*; D045473:Severe acute respiratory syndrome-related coronavirus / Q000502:physiology*; D014161:Transduction, Genetic; D053585:Virus Attachment
chemical_list: D011991:Receptors, Virus; D007703:Peptidyl-Dipeptidase A; C000705307:ACE2 protein, human; D000085962:Angiotensin-Converting Enzyme 2