Abstract
The viral enzyme integrase (IN) is essential for the replication of human immunodeficiency virus type 1 (HIV-1) and represents an important target for the development of new antiretroviral drugs. In this study, we focused on the N-terminal domain (NTD), which is mainly involved into protein oligomerization process, for the development and synthesis of a library of overlapping peptide sequences, with specific length and specific offset covering the entire native protein sequence NTD IN 1–50. The most potent fragment, VVAKEIVAH (peptide 18), which includes a His residue instead of the natural Ser at position 39, inhibits the HIV-1 IN activity with an IC50 value of 4.5 μM. Amino acid substitution analysis on this peptide revealed essential residues for activity and allowed us to identify two nonapeptides (peptides 24 and 25), that show a potency of inhibition similar to the one of peptide 18. Interestingly, peptide 18 does not interfere with the dynamic interplay between IN subunits, while peptides 24 and 25 modulated these interactions in different manners. In fact, peptide 24 inhibited the IN-IN dimerization, while peptide 25 promoted IN multimerization, with IC50 values of 32 and 4.8 μM, respectively. In addition, peptide 25 has shown to have selective anti-infective cell activity for HIV-1. These results confirmed peptide 25 as a hit for further development of new chemotherapeutic agents against HIV-1.
Highlights
Integrase (IN) is a key enzyme for the integration of the human immunodeficiency virus type 1 (HIV-1) genome into the host cell chromosome and, a very promising target for anti-AIDS drug design
Starting from HIV-1 IN N-terminal domain (NTD) we synthesized an overlapping peptide library to generate a library of peptide sequences of specific length and specific offset, to cover the entire native protein sequence NTD IN 1–50
The relevance of both a α-helix structure and a Zn2+ chelating group on the inhibitory activity was assessed by the synthesis of three peptides derived from peptide 11, in which the Cys residue was deleted or substituted by His amino acid a residue involved in the Zn2+ coordination (Wolfe et al, 2001; Liao et al, 2013)
Summary
Integrase (IN) is a key enzyme for the integration of the HIV-1 genome into the host cell chromosome and, a very promising target for anti-AIDS drug design. Following translocation to the nucleus, IN uses the hydroxyl ends as a substrate reaction for a nucleophilic attack integrating the viral genome in the host chromosomal DNA (strand-transfer reaction, STIN) (Semenova et al, 2006; Delelis et al, 2008). The N-terminal domain (NTD, residues 1–50) contains a zinc-binding H12H16C40C43 motif and contributes to protein oligomerization process (Engelman and Craigie, 1992; Cai et al, 1997). The central domain (CCD, residues 51–212) encloses the enzyme active site characterized by the catalytic triad D64D116E152, which is highly conserved in all INs, with the two residues D64 and D116 forming a coordination complex with divalent ions like Mn2+ and Mg2+ (Goldgur et al, 1998; Chen et al, 2000). The C-terminal domain (CTD, residues 213–288), which is the least conserved domain between retroviral INs, binds non- to DNA and is involved in IN multimerization (Chen et al, 2000)
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