Inhibitory effect of the polyanionic drug suramin on the in vitro HIV DNA integration reaction

An obligatory step in retroviral growth is the integration of a DNA copy of the viral RNA into the genomic DNA of the host. Recombinant human immunodeficiency virus type I (HIV-1) integrase (IN) expressed in Escherichia coli efficiently catalyzes the overall in vitro integration reaction, namely the processing of the LTR ends and the strand transfer reaction. Using the 3' end of synthetic oligonucleotides which match the termini of the HIV-1 U5 LTR as substrate and supercoiled pSP65 DNA as target, we have investigated the effect of the polyanionic drug suramin on the catalytic activity of the IN protein. It was found that at stoichiometric suramin to protein ratios, suramin displays a strong inhibitory effect on both the processing and strand transfer reactions. This inhibitory effect is related to the decrease of IN protein binding efficiency to the LTR end DNA fragment.