Structural basis of receptor recognition by SARS-CoV-2

Area of Science:

• Virology
• Structural Biology
• Biochemistry

Background:

• A novel coronavirus, SARS-CoV-2, causes the COVID-19 pandemic.
• Understanding viral entry mechanisms, specifically receptor recognition, is vital for controlling SARS-CoV-2.
• Both SARS-CoV-2 and SARS-CoV utilize human angiotensin-converting enzyme 2 (ACE2) as their cellular receptor.

Purpose of the Study:

• To determine the crystal structure of the SARS-CoV-2 spike protein's receptor-binding domain (RBD) in complex with human ACE2.
• To elucidate the structural basis for the enhanced ACE2 binding affinity of SARS-CoV-2 compared to SARS-CoV.
• To investigate the ACE2 recognition mechanism of RaTG13, a bat coronavirus closely related to SARS-CoV-2.

Main Methods:

• X-ray crystallography to determine the structure of the SARS-CoV-2 RBD-ACE2 complex.
• Comparative structural analysis between SARS-CoV-2 RBD and SARS-CoV RBD.
• Functional assays to assess ACE2 binding affinity and receptor usage.

Main Results:

• The crystal structure revealed a more compact ACE2-binding ridge in SARS-CoV-2 RBD compared to SARS-CoV RBD.
• Specific residue changes in SARS-CoV-2 RBD stabilize critical binding hotspots at the RBD-ACE2 interface, increasing binding affinity.
• RaTG13, a related bat coronavirus, also uses human ACE2, suggesting shared receptor recognition mechanisms.

Conclusions:

• The structural features of SARS-CoV-2 RBD enhance its binding affinity to human ACE2, potentially contributing to its efficient transmission.
• Comparative analysis of ACE2 recognition among SARS-CoV-2, SARS-CoV, and RaTG13 provides insights into potential zoonotic origins and interspecies transmission.
• This structural understanding guides the development of targeted intervention strategies against SARS-CoV-2 entry.