A Virus-Binding Hot Spot on Human Angiotensin-Converting Enzyme 2 Is Critical for Binding of Two Different Coronaviruses

Department of Pharmacology, University of Minnesota Medical School, Minneapolis, MN 55455, USA.
Journal of Virology (Impact Factor: 4.44). 03/2011; 85(11):5331-7. DOI: 10.1128/JVI.02274-10
Source: PubMed


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.

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    • "As civet (c) ACE2 displayed affinity for both human (Tor2 and GD03) and civet SARS-CoV isolates (Sz02 and Gd05), while human (h) ACE2 preferentially bound the S protein RBD of human isolates, biochemical studies were performed to define mutations influencing RBD affinity (Li, 2008; Wu et al., 2012, 2011; Li et al., 2005b). These studies identified two regions of interaction between the S protein RBD and ACE2 at which mutations evolved to accommodate a switch in preference from cACE2 to hACE2 (Li, 2008; Wu et al., 2012, 2011). The two regions were designated hotspot 31 and hotspot 353. "
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    Preview · Article · Mar 2015 · Virology
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    • "The antiviral activity found is ∼3× more pronounced than the activity against the SARS coronavirus (Li et al., 2003; Ivens et al., 2005). This is not unexpected since both viruses are known to bind the ACE2 receptor differently and have evolved independently in their ability to use it for cellular entry (Wu et al., 2011). "
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