Researchers at the Francis Crick Institute have compared the original SARS-CoV-2 spike protein with a mutated version that arose last spring.
They have found structural differences that could help to explain why the mutated version remains the dominant form circulating in all recent variants of concern, such as the UK and South African strains.
As SARS-CoV-2 has evolved, mutations impacting the structure of the viral spike protein have affected how it binds to and infects cells.
These changes have had huge implications for the spread of disease as new variants dominate, in part due to changes in the fitness of the virus.
The scientists used electron cryomicroscopy to gain detailed images of a variant form of SARS-CoV-2 spike protein. They then compared this with a previous study examining the original “Wuhan” form of the virus. The variant spike, called G614, is a mutated version that first arose around spring 2020 and is now the dominant version of the spike in circulation, including in the recently identified variants of concern.
By analysing their structures, the researchers found that the mutated G614 spike would more easily bind to human cells due to its open and flexible structure. While the original spike adopted a generally more closed form, they observed that the mutant spike could adopt a greater number of open and erect conformations, which would prime the protein for binding to the human cell receptor ACE2.
