Limits...
Rational improvement of gp41-targeting HIV-1 fusion inhibitors: an innovatively designed Ile-Asp-Leu tail with alternative conformations

View Article: PubMed Central - PubMed

ABSTRACT

Peptides derived from the C-terminal heptad repeat (CHR) of HIV gp41 have been developed as effective fusion inhibitors against HIV-1, but facing the challenges of enhancing potency and stability. Here, we report a rationally designed novel HIV-1 fusion inhibitor derived from CHR-derived peptide (Trp628~Gln653, named CP), but with an innovative Ile-Asp-Leu tail (IDL) that dramatically increased the inhibitory activity by up to 100 folds. We also determined the crystal structures of artificial fusion peptides N36- and N43-L6-CP-IDL. Although the overall structures of both fusion peptides share the canonical six-helix bundle (6-HB) configuration, their IDL tails adopt two different conformations: a one-turn helix with the N36, and a hook-like structure with the longer N43. Structural comparison showed that the hook-like IDL tail possesses a larger interaction interface with NHR than the helical one. Further molecular dynamics simulations of the two 6-HBs and isolated CP-IDL peptides suggested that hook-like form of IDL tail can be stabilized by its binding to NHR trimer. Therefore, CP-IDL has potential for further development as a new HIV fusion inhibitor, and this strategy could be widely used in developing artificial fusion inhibitors against HIV and other enveloped viruses.

No MeSH data available.


Two different conformations of IDL tail in fusion inhibitor CP-IDL.(A) Crystal structure of N36-L6-C34 (PDB: 1AIK), N36-L6-CP-IDL and N43-L6-CP-IDL, shown in both side view and cross-section view. NHR is colored in grey, C34 in blue. In N36-L6-CP-IDL, CP in forest and IDL in violet. In N43-L6-CP-IDL, CP in split pea and IDL in magentas, extend region of N43 in cyan. (B) Superposition of two crystal structures in the tail region, NHR are shown as electrostatic surface.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
getmorefigures.php?uid=PMC5036048&req=5

f2: Two different conformations of IDL tail in fusion inhibitor CP-IDL.(A) Crystal structure of N36-L6-C34 (PDB: 1AIK), N36-L6-CP-IDL and N43-L6-CP-IDL, shown in both side view and cross-section view. NHR is colored in grey, C34 in blue. In N36-L6-CP-IDL, CP in forest and IDL in violet. In N43-L6-CP-IDL, CP in split pea and IDL in magentas, extend region of N43 in cyan. (B) Superposition of two crystal structures in the tail region, NHR are shown as electrostatic surface.

Mentions: To explore the exact binding mode of the artificial IDL tail, we first determined the crystal structure of a fusion peptide N36-L6-CP-IDL, where N36 is a NHR peptide widely employed in the structural studies of HIV-1 fusion core. Unexpectedly, well-defined electron density (Fig. S2A) shows that the whole CP-IDL folds into a continuous α-helix (Fig. 2A), which can be perfectly superimposed to the C34 peptide in 6-HB structure (Fig. 2B), despite the significant difference between their tail sequences (the counterpart of Ile-Asp-Leu in C34 is Glu-Lys-Asn, Fig. 1A). By forming almost one turn of the helix, the isoleucine and aspartic acid residues of IDL are located at the outer side and hence have no interactions with N36, while the leucine residue participates in hydrophobic interactions with Ile548 and Val549 from two adjacent NHR helices, respectively (Fig. 3A). The interface area between one CP-IDL and trimeric NHR is 1098~1218 Å2, where IDL tails contribute 66~124 Å2 (approximately 10%). In addition, we noticed that, “below” the N-terminus of N36, there are plenty of space allowing more residues from NHR to interact with IDL tail, of which the structural features cannot be unveiled by the structure of N36-L6-CP-IDL.


Rational improvement of gp41-targeting HIV-1 fusion inhibitors: an innovatively designed Ile-Asp-Leu tail with alternative conformations
Two different conformations of IDL tail in fusion inhibitor CP-IDL.(A) Crystal structure of N36-L6-C34 (PDB: 1AIK), N36-L6-CP-IDL and N43-L6-CP-IDL, shown in both side view and cross-section view. NHR is colored in grey, C34 in blue. In N36-L6-CP-IDL, CP in forest and IDL in violet. In N43-L6-CP-IDL, CP in split pea and IDL in magentas, extend region of N43 in cyan. (B) Superposition of two crystal structures in the tail region, NHR are shown as electrostatic surface.
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5036048&req=5

f2: Two different conformations of IDL tail in fusion inhibitor CP-IDL.(A) Crystal structure of N36-L6-C34 (PDB: 1AIK), N36-L6-CP-IDL and N43-L6-CP-IDL, shown in both side view and cross-section view. NHR is colored in grey, C34 in blue. In N36-L6-CP-IDL, CP in forest and IDL in violet. In N43-L6-CP-IDL, CP in split pea and IDL in magentas, extend region of N43 in cyan. (B) Superposition of two crystal structures in the tail region, NHR are shown as electrostatic surface.
Mentions: To explore the exact binding mode of the artificial IDL tail, we first determined the crystal structure of a fusion peptide N36-L6-CP-IDL, where N36 is a NHR peptide widely employed in the structural studies of HIV-1 fusion core. Unexpectedly, well-defined electron density (Fig. S2A) shows that the whole CP-IDL folds into a continuous α-helix (Fig. 2A), which can be perfectly superimposed to the C34 peptide in 6-HB structure (Fig. 2B), despite the significant difference between their tail sequences (the counterpart of Ile-Asp-Leu in C34 is Glu-Lys-Asn, Fig. 1A). By forming almost one turn of the helix, the isoleucine and aspartic acid residues of IDL are located at the outer side and hence have no interactions with N36, while the leucine residue participates in hydrophobic interactions with Ile548 and Val549 from two adjacent NHR helices, respectively (Fig. 3A). The interface area between one CP-IDL and trimeric NHR is 1098~1218 Å2, where IDL tails contribute 66~124 Å2 (approximately 10%). In addition, we noticed that, “below” the N-terminus of N36, there are plenty of space allowing more residues from NHR to interact with IDL tail, of which the structural features cannot be unveiled by the structure of N36-L6-CP-IDL.

View Article: PubMed Central - PubMed

ABSTRACT

Peptides derived from the C-terminal heptad repeat (CHR) of HIV gp41 have been developed as effective fusion inhibitors against HIV-1, but facing the challenges of enhancing potency and stability. Here, we report a rationally designed novel HIV-1 fusion inhibitor derived from CHR-derived peptide (Trp628~Gln653, named CP), but with an innovative Ile-Asp-Leu tail (IDL) that dramatically increased the inhibitory activity by up to 100 folds. We also determined the crystal structures of artificial fusion peptides N36- and N43-L6-CP-IDL. Although the overall structures of both fusion peptides share the canonical six-helix bundle (6-HB) configuration, their IDL tails adopt two different conformations: a one-turn helix with the N36, and a hook-like structure with the longer N43. Structural comparison showed that the hook-like IDL tail possesses a larger interaction interface with NHR than the helical one. Further molecular dynamics simulations of the two 6-HBs and isolated CP-IDL peptides suggested that hook-like form of IDL tail can be stabilized by its binding to NHR trimer. Therefore, CP-IDL has potential for further development as a new HIV fusion inhibitor, and this strategy could be widely used in developing artificial fusion inhibitors against HIV and other enveloped viruses.

No MeSH data available.