Researchers from China have discovered how the novel coronavirus binds with and infects human cells, in a finding that will help develop viral detection techniques and potential antiviral therapies, reports Science Mag.
Coronavirus binds with human cells via ACE2 enzyme
Researchers in China used a process called cryogenic electron microscopy and found that coronavirus enters human cells using a glycoprotein called SARS-CoV-2 spike (S), which binds to the human cell membrane protein angiotensin-converting enzyme 2 (ACE2), via which the virus enters human cells.
As the coronavirus infects a human cell, the S protein is cleaved into subunits, S1 and S2. S1 holds a receptor-binding domain (RBD), which is how COVID-19 can directly bind to the peptidase domain (PD) of ACE2. S2 is thought to play a further role in cellular fusion.
This is why Chinese researchers used cryogenic electron microscopy (cryo-EM) to map the structure of the ACE2 while it's joined to an amino acid transporter called B0AT1. The scientists also found how COVID-19 may connect to another complex structure called ACE2-B0AT1.
New study may help develop antivirals or vaccine
The study also suggests that ACE2 needs to undergo a molecular process where it binds with another identical molecule to be active, or, in other words: infectious. The resulting molecule can bind two COVID-19 S protein molecules at the same time.
The scientists also studied the ways SARS-CoV-2 RBD binds differently compared to how other SARS-CoV-RBDs bind, which showed how subtle changes in the molecular binding sequence makes the structure of the coronavirus stronger, while others reduce its structural integrity.
The scientists concluded that their research may inform global efforts to design new antibodies customized to specifically target ACE2 or other coronavirus spike proteins, which would prevent coronavirus infection.