Post by Nadica (She/Her) on Oct 3, 2024 4:46:00 GMT
Oligomerization-driven avidity correlates with SARS-CoV-2 cellular binding and inhibition - Published Sept 19, 2024
Significance
Viral entry is mediated by interactions between multivalent proteins, which are difficult to capture with current structural and biophysical methods owing to the underlying heterogeneity and requirement for a membrane surface. Here, we use mass photometry to quantify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) interaction and inhibition taking place in solution and on lipid membranes. We show that multivalency and cooperativity control the spike–angiotensin-converting enzyme 2 (ACE2) interactions making the general reduction to a 1:1 interaction model inadequate to capture the underlying molecular dynamics. We find evidence for ACE2 inducing spike oligomerization in a variant-dependent manner that enhances its cellular affinity by driving receptor clustering. In addition, induced oligomerization emerges as a fundamental mode of action of antibodies, operating on its own, or combined with traditional receptor blocking.
Abstract
Cellular processes are controlled by the thermodynamics of the underlying biomolecular interactions. Frequently, structural investigations use one monomeric binding partner, while ensemble measurements of binding affinities generally yield one affinity representative of a 1:1 interaction, despite the majority of the proteome consisting of oligomeric proteins. For example, viral entry and inhibition in SARS-CoV-2 involve a trimeric spike surface protein, a dimeric angiotensin-converting enzyme 2 (ACE2) cell-surface receptor and dimeric antibodies. Here, we reveal that cooperativity correlates with infectivity and inhibition as opposed to 1:1 binding strength. We show that ACE2 oligomerizes spike more strongly for more infectious variants, while exhibiting weaker 1:1 affinity. Furthermore, we find that antibodies use induced oligomerization both as a primary inhibition mechanism and to enhance the effects of receptor-site blocking. Our results suggest that naive affinity measurements are poor predictors of potency, and introduce an antibody-based inhibition mechanism for oligomeric targets. More generally, they point toward a much broader role of induced oligomerization in controlling biomolecular interactions.
Significance
Viral entry is mediated by interactions between multivalent proteins, which are difficult to capture with current structural and biophysical methods owing to the underlying heterogeneity and requirement for a membrane surface. Here, we use mass photometry to quantify severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) interaction and inhibition taking place in solution and on lipid membranes. We show that multivalency and cooperativity control the spike–angiotensin-converting enzyme 2 (ACE2) interactions making the general reduction to a 1:1 interaction model inadequate to capture the underlying molecular dynamics. We find evidence for ACE2 inducing spike oligomerization in a variant-dependent manner that enhances its cellular affinity by driving receptor clustering. In addition, induced oligomerization emerges as a fundamental mode of action of antibodies, operating on its own, or combined with traditional receptor blocking.
Abstract
Cellular processes are controlled by the thermodynamics of the underlying biomolecular interactions. Frequently, structural investigations use one monomeric binding partner, while ensemble measurements of binding affinities generally yield one affinity representative of a 1:1 interaction, despite the majority of the proteome consisting of oligomeric proteins. For example, viral entry and inhibition in SARS-CoV-2 involve a trimeric spike surface protein, a dimeric angiotensin-converting enzyme 2 (ACE2) cell-surface receptor and dimeric antibodies. Here, we reveal that cooperativity correlates with infectivity and inhibition as opposed to 1:1 binding strength. We show that ACE2 oligomerizes spike more strongly for more infectious variants, while exhibiting weaker 1:1 affinity. Furthermore, we find that antibodies use induced oligomerization both as a primary inhibition mechanism and to enhance the effects of receptor-site blocking. Our results suggest that naive affinity measurements are poor predictors of potency, and introduce an antibody-based inhibition mechanism for oligomeric targets. More generally, they point toward a much broader role of induced oligomerization in controlling biomolecular interactions.