A novel short peptide is a specific inhibitor of the human immunodeficiency virus type 1 integrase

The retroviral encoded protein integrase (IN) is required for the insertion of the human immunodeficiency virus type 1 (HIV-1) proviral DNA into the host genome. In spite of the crucial role played by IN in the retroviral life cycle, which makes this enzyme an attractive target for the development of new anti-AIDS agents, very few inhibitors have been described and none seems to have a potential use in anti-HIV therapy. To obtain potent and specific IN inhibitors, we used the two-hybrid system to isolate short peptides. Using HIV-1 IN as a bait and a yeast genomic library as the source of inhibitory peptides (prey), we isolated a 33-mer peptide (I33) that bound tightly to the enzyme. I33 inhibited both in vitro IN activities, i.e. 3' end processing and strand transfer. Further analysis led us to select a shorter peptide, EBR28, corresponding to the N-terminal region of I33. Truncated variants showed that EBR28 interacted with the catalytic domain of IN interfering with the binding of the DNA substrate. Alanine single substitution of each EBR28 residue (alanine scanning) allowed the identification of essential amino acids involved in the inhibition. The EBR28 NMR structure shows that this peptide adopts an alpha-helical conformation with amphipathic properties. Additionally, EBR28 showed a significant antiviral effect when assayed on HIV-1 infected human cells. Thus, this potentially important short lead peptide may not only be helpful to design new anti-HIV agents, but also could prove very useful in further studies of the structural and functional characteristics of HIV-1 IN.