Interaction Between SARS-CoV-2 Spike Protein S1 Subunit and Oyster Heat Shock Protein 70

Area of Science:

• Environmental Science
• Virology
• Biochemistry

Background:

• Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) has been detected in marine environments.
• Filter-feeding shellfish, like Pacific oysters, can bioaccumulate SARS-CoV-2.
• Oyster heat shock protein 70 (oHSP70) is a potential binding receptor for SARS-CoV-2's spike protein S1 subunit (rS1).

Purpose of the Study:

• To investigate the binding interaction between recombinant oHSP70 (roHSP70) and SARS-CoV-2 rS1.
• To determine the affinity of roHSP70 for rS1 and compare it to known interactions.
• To identify key regions and amino acids in roHSP70 involved in rS1 binding.

Main Methods:

• Surface Plasmon Resonance (SPR)-based Biacore assays to measure binding affinity (K_D).
• Enzyme-Linked Immunosorbent Assay (ELISA) for validation.
• Construction and testing of truncated and mutated roHSP70 proteins based on molecular docking.

Main Results:

• The binding affinity of roHSP70 for rS1 (K_D = 20.4 nM) is comparable to rACE2 for rS1 (K_D = 16.7 nM).
• All tested truncated segments (N, C, M) and mutated sites of roHSP70 showed significantly reduced affinity for rS1.
• These findings indicate that multiple regions and specific amino acids of roHSP70 are involved in binding to SARS-CoV-2 rS1.

Conclusions:

• roHSP70 exhibits a strong binding affinity for SARS-CoV-2 rS1, suggesting its role in virus bioaccumulation in oysters.
• The study provides a theoretical foundation for understanding SARS-CoV-2 uptake in shellfish.
• roHSP70 can be explored as a potential capture agent for detecting SARS-CoV-2 in environmental samples.