Post by Nadica (She/Her) on Nov 2, 2024 5:46:42 GMT
Facilitating and restraining virus infection using cell-attachable soluble viral receptors - Published Oct 31, 2024
Significance
Understanding the mechanism of receptor usage by SARS-CoV-2 is crucial for antiviral treatment. Angiotensin converting enzyme 2 (ACE2) is the known entry receptor for the SARS-CoV-2 spike protein. Our findings reveal that for a protein to function as an entry receptor for SARS-CoV-2, it needs to satisfy two essential criteria: interaction with the spike receptor-binding domain (RBD) and close proximity to the cell membrane. Following this rule, RBD-binding SARS-CoV-2 inhibitory proteins, such as neutralizing antibodies and nanobodies, when present on the cell surface, all act as entry receptors. We have applied this knowledge in engineering cell-attachable RBD-binders with significantly improved antiviral activity and for converting cell surface proteins into viral receptors to facilitate virus infection in various virus-based applications.
Abstract
SARS-CoV-2 uses the receptor binding domain (RBD) of its spike protein to recognize and infect host cells by binding to the cell surface receptor angiotensin converting enzyme 2 (ACE2). The ACE2 receptor is composed of peptidase domain (PD), collectrin-like domain, transmembrane domain, and short cytoplasmic domain, and may exist as a dimer on cell surface. The RBD binding site is located atop of the ACE2 PD, but the involvement of other domains in virus infection is uncertain. We found that the ACE2 PD alone, whether anchored to cell membrane via a glycosylphosphatidylinositol anchor or attached to another surface protein, is fully functional as a receptor for spike-mediated cell fusion and virus infection. However, for ACE2 to function as the viral receptor, the RBD binding site must be positioned in close proximity to the cell membrane. Elevating the surface height of ACE2 using long and rigid protein spacers reduces or eliminates cell fusion and virus infection. Moreover, we found that the RBD-targeting neutralizing antibodies, nanobodies, and de novo designed miniprotein binders, when present on cell surface, also act as viral receptors, facilitating cell fusion and virus infection. Our data demonstrate that RBD binding and close membrane proximity are essential properties for a receptor to effectively mediate SARS-CoV-2 infection. Importantly, we show that soluble RBD-binders can be engineered to make cells either susceptible or resistant to virus infection, which has significant implications for antiviral therapy and various virus-mediated applications.
Significance
Understanding the mechanism of receptor usage by SARS-CoV-2 is crucial for antiviral treatment. Angiotensin converting enzyme 2 (ACE2) is the known entry receptor for the SARS-CoV-2 spike protein. Our findings reveal that for a protein to function as an entry receptor for SARS-CoV-2, it needs to satisfy two essential criteria: interaction with the spike receptor-binding domain (RBD) and close proximity to the cell membrane. Following this rule, RBD-binding SARS-CoV-2 inhibitory proteins, such as neutralizing antibodies and nanobodies, when present on the cell surface, all act as entry receptors. We have applied this knowledge in engineering cell-attachable RBD-binders with significantly improved antiviral activity and for converting cell surface proteins into viral receptors to facilitate virus infection in various virus-based applications.
Abstract
SARS-CoV-2 uses the receptor binding domain (RBD) of its spike protein to recognize and infect host cells by binding to the cell surface receptor angiotensin converting enzyme 2 (ACE2). The ACE2 receptor is composed of peptidase domain (PD), collectrin-like domain, transmembrane domain, and short cytoplasmic domain, and may exist as a dimer on cell surface. The RBD binding site is located atop of the ACE2 PD, but the involvement of other domains in virus infection is uncertain. We found that the ACE2 PD alone, whether anchored to cell membrane via a glycosylphosphatidylinositol anchor or attached to another surface protein, is fully functional as a receptor for spike-mediated cell fusion and virus infection. However, for ACE2 to function as the viral receptor, the RBD binding site must be positioned in close proximity to the cell membrane. Elevating the surface height of ACE2 using long and rigid protein spacers reduces or eliminates cell fusion and virus infection. Moreover, we found that the RBD-targeting neutralizing antibodies, nanobodies, and de novo designed miniprotein binders, when present on cell surface, also act as viral receptors, facilitating cell fusion and virus infection. Our data demonstrate that RBD binding and close membrane proximity are essential properties for a receptor to effectively mediate SARS-CoV-2 infection. Importantly, we show that soluble RBD-binders can be engineered to make cells either susceptible or resistant to virus infection, which has significant implications for antiviral therapy and various virus-mediated applications.