Abstract: The protein-protein interaction (PPI) between human transporter SR2 (TRN-SR2) and HIV-1 integrase (IN) is an effective target for anti-HIV therapy. It has important clinical significance and broad application prospects to find and design effective inhibitors of this PPI. In order to screen inhibitors targeting the PPI between TRN-SR2 and HIV-1 IN, the recombinant TRN-SR2 proteins were expressed in E. coli Rosetta (DE3) and purified by GST affinity chromatography column. The result showed that the recombinant TRN-SR2 protein was obtained with a concentration of 0.80 mg/mL. The interaction between TRN-SR2 and HIV-1 IN was confirmed in vitro by biofilm interferometry (BLI). The results showed that the binding signal increased significantly with TRN-SR2 binding to HIV-1 IN and the equilibrium dissociation constant (KD) was determined as 45.2 nmol/L. The optimal reaction concentrations of TRN-SR2 and HIV-1 IN in the target inhibitor screening system were determined by homogeneous time-resolved fluorescence (HTRF) and cross-titration experiments, which were 20 and 40 nmol/L, respectively. All these results suggested that the recombinant TRN-SR2 protein was biologically active and could effectively interact with HIV-1 IN in vitro. The determination of the optimal concentration of TRN-SR2 and HIV-1IN in the screening system also provides a basis for the subsequent screening of inhibitors.

Key words: HIV-1 integrase, TRN-SR2, protein-protein interaction, BLI, HTRF