Subtle Influence of ACE2 Glycan Processing on SARS-CoV-2 Recognition

Area of Science:

• Virology
• Glycobiology
• Molecular Biology

Background:

• SARS-CoV-2 infection severity exhibits significant variability, with the underlying molecular mechanisms remaining unclear.
• Glycosylation, particularly sialic acid modifications on human cells, is a potential factor influencing SARS-CoV-2 binding.
• Both the SARS-CoV-2 spike glycoprotein and the human ACE2 receptor are heavily glycosylated, suggesting a role for these modifications.

Purpose of the Study:

• To investigate the impact of angiotensin-converting enzyme 2 (ACE2) glycosylation status on its interaction with the SARS-CoV-2 spike (S) protein.
• To determine if specific glycoforms of ACE2 affect viral binding.
• To elucidate the role of ACE2 glycosylation in the early stages of SARS-CoV-2 infection.

Main Methods:

• Generation of a panel of engineered ACE2 glycoforms.
• Mass spectrometry analysis to characterize site-specific glycan modifications on ACE2.
• Binding assays to assess the interaction between SARS-CoV-2 spike protein and engineered ACE2 glycoforms.

Main Results:

• Mass spectrometry confirmed distinct site-specific glycan modifications on the engineered ACE2 glycoforms.
• Hypersialylated or oligomannose-type ACE2 glycoforms showed a slight impediment to SARS-CoV-2 spike binding.
• Complete deglycosylation of ACE2 did not alter SARS-CoV-2 binding affinity.

Conclusions:

• ACE2 glycosylation does not appear to be a major determinant of SARS-CoV-2 binding.
• The influence of glycosylation on SARS-CoV-2 pathobiology may occur through mechanisms other than direct effects on ACE2 receptor binding.
• Further research is needed to explore alternative roles of glycosylation in SARS-CoV-2 infection dynamics.