Design of a novel peptide inhibitor of HIV fusion that disrupts the internal trimeric coiled-coil of gp41.
The pre-hairpin intermediate of gp41 from the human immunodeficiency virus (HIV) is the target for two classes of fusion inhibitors that bind to the C-terminal region or the trimeric coiled-coil of N-terminal helices, thereby preventing formation of the fusogenic trimer of hairpins. Using rational design, two 36-residue peptides, N36(Mut(e,g)) and N36(Mut(a,d)), were derived from the parent N36 peptide comprising the N-terminal helix of the gp41 ectodomain (residues 546-581 of HIV-1 envelope), characterized by analytical ultracentrifugation and CD, and assessed for their ability to inhibit HIV fusion using a quantitative vaccinia virus-based fusion assay. N36(Mut(e,g)) contains nine amino acid substitutions designed to disrupt interactions with the C-terminal region of gp41 while preserving contacts governing the formation of the trimeric coiled-coil. N36(Mut(a,d)) contains nine substitutions designed to block formation of the trimeric coiled-coil but retains residues that interact with the C-terminal region of gp41. N36(Mut(a,d)) is monomeric, is largely random coil, does not interact with the C34 peptide derived from the C-terminal region of gp41 (residues 628-661), and does not inhibit fusion. The trimeric coiled-coil structure is therefore a prerequisite for interaction with the C-terminal region of gp41. N36(Mut(e,g)) forms a monodisperse, helical trimer in solution, does not interact with C34, and yet inhibits fusion about 50-fold more effectively than the parent N36 peptide (IC(50) approximately 308 nm versus approximately 16 microm). These results indicate that N36(Mut(e,g)) acts by disrupting the homotrimeric coiled-coil of N-terminal helices in the pre-hairpin intermediate to form heterotrimers. Thus N36(Mut(e,g)) represents a novel third class of gp41-targeted HIV fusion inhibitor. A quantitative model describing the interaction of N36(Mut(e,g)) with the pre-hairpin intermediate is presented.
Bewley
Carole A
CA
Laboratories of Bioorganic Chemistry, Chemical Physics, and Molecular Biology, NIDDK, National Institutes of Health, Bethesda, Maryland 20892, USA. caroleb@intra.niddk.nih.gov
Louis
John M
JM
Ghirlando
Rodolfo
R
Clore
G Marius
GM
D000595:Amino Acid Sequence; D019380:Anti-HIV Agents / Q000494:pharmacology*; D002942:Circular Dichroism; D004305:Dose-Response Relationship, Drug; D015195:Drug Design; D006678:HIV / Q000378:metabolism*; D015700:HIV Envelope Protein gp41 / Q000737:chemistry*; D008954:Models, Biological; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry; D011487:Protein Conformation / Q000187:drug effects; D017434:Protein Structure, Tertiary; D014461:Ultracentrifugation
D019380:Anti-HIV Agents; D015700:HIV Envelope Protein gp41; D010455:Peptides