title: Helical and coiled-coil-forming properties of peptides derived from and inhibiting human immunodeficiency virus type 1 integrase assessed by 1H-NMR--use of NH temperature coefficients to probe coiled-coil structures.
abstract: Human immunodeficiency virus type 1 integrase (HIV-1 IN) which catalyzes viral DNA integration into the host genome of infected cells represents an attractive target for AIDS therapy. We have previously demonstrated the ability of the IN-(147-175)-peptide derived from the catalytic core domain of HIV-1 IN to inhibit the enzyme activity in vitro. IN-(147-175)-peptide contains four heptad repeats and displays a high propensity for coiled-coil formation while its [P159]IN-(147-175)-peptide analog (Lys159-->Pro in the protein, Lys13-->Pro in the peptide) is unable to form a stable coiled-coil and is devoid of inhibitory activity [Sourgen, F., Maroun, R. G., Frère, V., Bouziane, M., Auclair, C., Troalen, F. & Fermandjian, S. (1996) Eur. J. Biochem. 240, 765-773]. Now, we report results from an NMR study on IN-(147-175)-peptide and [P159]IN-(147- 175)-peptide as well as on an optimized [E156, A163, A167]IN-(147-175)-peptide that is a better inhibitor of IN than IN-(147-175)-peptide. While in aqueous solution, IN-(147-175)-peptide and [P159]IN-(147-175)-peptide display only nascent helical features, [E156, A163, A167]IN-(147-175)-peptide exhibits 20% of helical content. In 20% trifluoroethanol/80% H2O, the helix content is the highest for [E156, A163, A167]IN-(147-175)-peptide (approximately 70%) and the lowest for [P159]IN-(147-175)-peptide (approximately 40%), due to a local helix break caused by the Pro residue. The NHs of residues in the two central helical heptads (a-g) of IN-(147-175)-peptide and [E156, A163, A167]IN-(147-175)-peptide display a regular periodic variation of their temperature coefficients in 20% trifluoroethanol. The b, c and f residues on the hydrophilic face of the amphipathic helix show high coefficients reflecting hydrogen bonded NHs, while the a and d residues on the hydrophobic face exhibit low coefficients, near random-coil values. The particular arrangement of the hydrophobic side-chains of a and d residues at the coiled-coil interface reduces the access of trifluoroethanol molecules to their amide groups. The inability of trifluoroethanol molecules to create interactions with the amide C=O groups, these being required to strengthen the intrahelical C=O...H-N hydrogen bonds, is the main cause for observation of heptadic a and d residues with low NH temperature coefficients. Such effects concern mostly the two central helical heptads of IN-(147-175)-peptide and [E156, A163, A167]IN-(147-175)-peptide implying that these ones are engaged in stable parallel coiled coils. Our results provide a link between the propensity of peptides for helix formation, their coiled-coil properties and their efficiency to inhibit IN.
authors.affiliation: Laboratoire de RMN, UPRES-A CNRS 6014, IRCOF, IFRMP n 23, Mont Saint-Aignan, France.
authors.forename: D
authors.initials: D
authors.lastname: Krebs
authors.forename: R G
authors.initials: RG
authors.lastname: Maroun
authors.forename: F
authors.initials: F
authors.lastname: Sourgen
authors.forename: F
authors.initials: F
authors.lastname: Troalen
authors.forename: D
authors.initials: D
authors.lastname: Davoust
authors.forename: S
authors.initials: S
authors.lastname: Fermandjian
mesh_terms: D000595:Amino Acid Sequence; D019427:HIV Integrase / Q000737:chemistry*; D019428:HIV Integrase Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D015497:HIV-1 / Q000201:enzymology*; D006801:Humans; D006860:Hydrogen Bonding; D009682:Magnetic Resonance Spectroscopy; D008969:Molecular Sequence Data; D010446:Peptide Fragments / Q000737:chemistry / Q000494:pharmacology; D017433:Protein Structure, Secondary; D013696:Temperature
chemical_list: D019428:HIV Integrase Inhibitors; D010446:Peptide Fragments; D019427:HIV Integrase