The human immunodeficiency virus type 1 (HIV-1) integrase (IN) protein is an emerging target for the development of anti-HIV drugs. We recently described a new approach for inhibiting IN by "shiftides"-peptides that inhibit the protein by shifting its oligomerization equilibrium from the active dimer to the inactive tetramer. In this study, we used the yeast two-hybrid system with the HIV-1 IN as a bait and a combinatorial peptide aptamer library as a prey to select peptides of 20 amino acids that specifically bind IN. Five non-homologous peptides, designated as IN-1 to IN-5, were selected. ELISA studies confirmed that IN binds the free peptides. All the five peptides interact with IN with comparable affinity (Kd≈10 μM), as was revealed by fluorescence anisotropy studies. Only one peptide, IN-1, inhibited the enzymatic activity of IN in vitro and the HIV-1 replication in cultured cells. In correlation, fluorescence anisotropy binding experiments revealed that of the five peptides, only the inhibitory IN-1 inhibited the DNA binding of IN. Analytical gel filtration experiments revealed that only the IN-1 and not the four other peptides shifted the oligomerization equilibrium of IN towards the tetramer. Thus, the results show a distinct correlation between the ability of the selected peptides to inhibit IN activity and that to shift its oligomerization equilibrium.
Bibliographical noteFunding Information:
This work was supported in part by grants from the Israel Science Foundation, Israel Ministry of Health (grant no. 888/05) and Austrian National Bank (to A.L.), by an institutional Bikura grant from the Israeli Science Foundation (to A.F.) and by the Horowitz Foundation (to A.L. and A.F.). The following reagent was obtained through the AIDS Research and Reference Reagent Program of the Division of AIDS, National Institute of Allergy and Infectious Diseases, NIH: HIV-1 Consensus B Pol (15-mer) peptides (complete set from National Institute of Allergy and Infectious Diseases Division of AIDS). We thank Dr. M. Kotler for his critical reading of the manuscript.
- fluorescence anisotropy
- synthetic peptides
- yeast two-hybrid