A Short Lipopeptide Derived from the N-Heptad Repeat Region Inhibits HIV-1 Gp41 Mediated Fusion Via an Altered Mode of Action

Abstract

Human immunodeficiency virus (HIV-1) fusion is mediated by the gp41 subunit of the envelope glycoprotein (ENV). Folding into the post-fusion conformation is apparently the rate limiting step for the fusion reaction and it enables inhibition of the fusion process. This is demonstrated by the inhibitory capability of N- or C-peptides derived from the N-or C-terminal heptad repeat (NHR or CHR) regions, respectively. These peptides have been shown to bind their endogenous counterparts thereby preventing progression into the post-fusion conformation and arresting fusion. Since N-peptides tend to aggregate, C-peptides are more potent fusion inhibitors, and therefore, attracted most therapeutic effort and research. Here we show that a short peptide derived from the classical NHR region is highly potent inhibitor only when linked to a fatty acid at the N- and not the C-terminus. To our knowledge, this is the shortest potent inhibitory peptide derived from the NHR region. Using biophysical and cellular approaches, we: (i) revealed that its mode of action is altered from other classical N-peptide, and (ii) suggest a new motif in the NHR involved in stabilization of the post-fusion conformation. Besides shedding light on the mechanism of HIV-cell fusion, the similarity between the ENV of lentiviruses provides a new approach for designing short inhibitors from the NHR region of other viruses as well.