Abstract
BackgroundInsertion of T4 lysozyme (T4L) into the GPCR successfully enhanced GPCR protein stability and solubilization. However, the biological functions of the recombinant GPCR protein have not been analyzed.MethodsWe engineered the CCR5-T4L mutant and expressed and purified the soluble recombinant protein using an E.coli expression system. The antiviral effects of this recombinant protein in THP-1 cell lines, primary human macrophages, and PBMCs from different donors were investigated. We also explored the possible mechanisms underlying the observed antiviral effects.ResultsOur data showed the biphasic inhibitory and promotion effects of different concentrations of soluble recombinant CCR5-T4L protein on R5 tropic human immunodeficiency virus-1 (HIV-1) infection in THP-1 cell lines, human macrophages, and PBMCs from clinical isolates. We demonstrated that soluble recombinant CCR5-T4L acts as a HIV-1 co-receptor, interacts with wild type CCR5, down-regulates the surface CCR5 expression in human macrophages, and interacts with CCL5 to inhibit macrophage migration. Using binding assays, we further determined that recombinant CCR5-T4L and [125I]-CCL5 compete for the same binding site on wild type CCR5.ConclusionsOur results suggest that recombinant CCR5-T4L protein marginally promotes HIV-1 infection at low concentrations and markedly inhibits infection at higher concentrations. This recombinant protein may be helpful in the future development of anti-HIV-1 therapeutic agents.
Highlights
CC chemokine receptor 5 (CCR5) belongs to the G protein-coupled receptor (GPCR) protein family
We demonstrated that soluble recombinant CCR5-T4 lysozyme (T4L) acts as a human immunodeficiency virus-1 (HIV-1) co-receptor, interacts with wild type CCR5, down-regulates the surface CCR5 expression in human macrophages, and interacts with CCL5 to inhibit macrophage migration
Our results suggest that recombinant CCR5-T4L protein marginally promotes HIV-1 infection at low concentrations and markedly inhibits infection at higher concentrations
Summary
CC chemokine receptor 5 (CCR5) belongs to the G protein-coupled receptor (GPCR) protein family. These proteins contain 7-transmembrane domains and mediate signal transduction events through their interaction with G proteins. CCR5 is a functional receptor for Chemokine (C-C motif) ligand 3 (CCL3 or MIP-1α), CCL4 (MIP-1β), CCL5 (RANTES), monocyte chemotactic protein (MCP)-2, and MCP-4 [1, 2]. Insertion of T4 lysozyme (T4L) into the GPCR successfully enhanced GPCR protein stability and solubilization. The biological functions of the recombinant GPCR protein have not been analyzed
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