N-Glycans modulate tilting of HIV-1 envelope glycoprotein

Area of Science:

• Structural Biology
• Virology
• Computational Biology

Background:

• Human immunodeficiency virus-1 (HIV-1) is a global health crisis with no available vaccine.
• The HIV-1 envelope glycoprotein (Env) mediates viral entry and is the primary target for immune responses.
• Understanding Env's structure and dynamics in its native membrane environment is crucial for therapeutic development.

Purpose of the Study:

• To investigate the molecular dynamics of the full-length, glycosylated HIV-1 Env glycoprotein in a lipid bilayer.
• To identify the role of N-linked glycans in modulating Env conformation and dynamics.
• To uncover potential vulnerabilities in the Env structure for immunogen design.

Main Methods:

• Microsecond-long, all-atom molecular dynamics simulations of glycosylated HIV-1 Env.
• Embedding the Env glycoprotein in a biologically relevant lipid bilayer.
• Corroboration of simulation results with cryo-electron tomography data.

Main Results:

• A pronounced tilting motion of the Env glycoprotein relative to the membrane was observed.
• N-linked glycans at positions N88 and N611 were identified as critical modulators of Env tilting.
• Specific sites of vulnerability within the Env glycan shield were illuminated.

Conclusions:

• HIV-1 Env exhibits significant tilting dynamics within the viral membrane.
• Glycan modifications at N88 and N611 play a key role in regulating Env's conformational flexibility.
• These findings provide insights into Env's immune evasion mechanisms and suggest avenues for novel immunogen design.