Clustering of HIV-1 Subtypes Based on gp120 V3 Loop electrostatic properties

Area of Science:

• Molecular biology
• Virology
• Biophysics

Background:

• The V3 loop of HIV-1 gp120 is crucial for viral entry, mediating coreceptor usage (CCR5/CXCR4) and influencing tropism.
• Electrostatic interactions are hypothesized to govern the V3 loop's binding to CCR5 and CXCR4.
• HIV-1 subtypes exhibit diverse V3 loop sequences and associated phenotypic tropisms.

Purpose of the Study:

• To investigate the role of electrostatic potentials and charge distributions in HIV-1 V3 loop structure and function.
• To analyze spatial electrostatic properties of V3 loop consensus sequences using hierarchical clustering.
• To correlate electrostatic features with coreceptor selectivity, prevalence, and geographic distribution.

Main Methods:

• Hierarchical clustering analysis of spatial electrostatic potentials and charges.
• Analysis of V3 loop consensus sequences from various HIV-1 subtypes.
• Correlation of electrostatic clustering with sequence data, net charge, and coreceptor tropism.

Main Results:

• While most V3 loops share a +3 net charge, spatial electrostatic distributions are key discriminators for binding and infectivity.
• Subcluster formation reveals common origins but distinct electrostatic properties, often lost in sequence-based clustering.
• Ionic strength affects electrostatic potential clustering, providing insights not seen with charge or sequence clustering alone.

Conclusions:

• Spatial distribution of electrostatic potentials and charges, alongside sequence and net charge, are critical for V3 loop-coreceptor recognition and viral entry.
• Electrostatic potential drives long-range V3 loop-coreceptor interaction, while charge distribution refines short-range binding.
• A model for coreceptor selectivity is proposed, integrating sequence, glycosylation motifs, and electrostatic properties.