Molecular interaction between HIV-1 major envelope glycoprotein and dextran sulfate

Area of Science:

• Molecular biology
• Virology
• Biochemistry

Background:

• HIV-1 entry relies on the interaction between the viral envelope glycoprotein gp160 and host cell receptors.
• Dextran sulfate is a sulfated polysaccharide with known anti-HIV-1 activity.
• The precise mechanism of dextran sulfate's antiviral action requires further elucidation at the molecular level.

Purpose of the Study:

• To investigate the molecular interaction between HIV-1 recombinant gp160 (rgp160) and low-molecular-weight dextran sulfate.
• To determine the specificity and affinity of this interaction.
• To explore the potential role of this interaction in the anti-HIV-1 activity of dextran sulfate.

Main Methods:

• Utilizing sulfated dextran beads to assess binding with rgp160.
• Performing inhibition assays with soluble dextran sulfate and dextran.
• Investigating the effect of pH on the interaction.
• Analyzing the inhibition of rgp160 binding to soluble recombinant CD4 (sT4) by dextran sulfate.

Main Results:

• Demonstrated a specific, saturable, and pH-dependent interaction between rgp160 and sulfated dextran beads.
• Showed that soluble dextran sulfate inhibited this interaction, while soluble dextran did not.
• Estimated a low affinity (Kd in the 10(-4) M range) for the rgp160-dextran sulfate interaction.
• Confirmed that dextran sulfate inhibits rgp160 binding to soluble recombinant CD4 (sT4) when pre-incubated with rgp160.

Conclusions:

• Confirmed a specific, albeit low-affinity, molecular interaction between dextran sulfate and HIV-1 rgp160.
• This interaction is distinct from the binding of rgp160 to CD4.
• The findings suggest that the interaction between dextran sulfate and rgp160 contributes to dextran sulfate's anti-HIV-1 activity.