Structural and functional similarities between synthetic HIV gp41 peptides and defensins.

Synthetic peptides derived from the putative immunosuppressive region of HIV-1 gp41 were examined to identify the amino acids required for suppressive activity. The active sequence was similar to the pseudosubstrate regulatory peptide of protein kinase C and to a sequence from the cyclic immune peptides known as defensins. The activity of the gp41 peptides appeared to be dependent upon a structural conformation, possibly a looped motif like that found in defensins. This similarity to defensins, which can insert themselves into lipid bilayers, was further strengthened by demonstrating that gp41 peptides have the ability to associate with liposomes and lymphocyte membranes. These results suggest that the immunosuppressive region of gp41 may participate in the membrane interactions required for viral fusion and infectivity.