title: Conformational and associative behaviours of the third helix of antennapedia homeodomain in membrane-mimetic environments.
abstract: The third helix of antennapedia homeodomain pAntp-(43-58) can translocate through cell membrane and has been used as an intracellular vehicle for delivering peptides and oligonucleotides. The conformational and associative behaviour of two peptidic vectors pAntp-(43-58) and [Pro50] pAntp-(43-58) has been analyzed by different biophysical methods. pAntp-(43-58) adopts an amphipathic helical structure in 30% (by vol.) hexafluoroisopropanol, in perfluoro-tert-butanol and in the presence of SDS micelles. CD spectra indicate that the conformation of [Pro50]pAntp-(43-58) in contrast to pAntp-(43-58) is independent of the media used. 1H-NMR spectroscopy in SDS micelles or in perfluoro-tert-butanol allows detection of aggregated peptides probably in a ribbon 2(7) type conformation. These conformations became the predominant structure when Gln50 was replaced by Pro50. Interproton-distance restraints derived from NOE measurements have been classified in two groups corresponding to two types of structures: alpha-helix and essentially extended structures. Consecutive CH alpha (i)/ CH alpha (i + 1) NOEs are only compatible with aggregates. Simulated annealing calculation of dimeric structure agrees with phi and psi angles in the beta-sheet and gamma-turn regions. Fluorescence spectroscopy analysis has shown that the indole groups of both peptides penetrate into SDS micelles; both peptides also induce the formation of micelles at very low concentration of SDS (20 microM). Similar interaction was observed with reverse-phase micelles made of bis(2-ethyhexyl) sodium sulfosuccinate and small unilamellar vesicles (SUV) made of a mixture of phosphatidylcholine/phosphatidylserine. 31P-NMR of vesicles (SUV and large unilamellar vesicles) indicated that the addition of pAntp analogues did not affect the size of phosphatidylcholine/phosphatidylserine vesicles. The addition of pAntp analogues to lipidic dispersions modulates lipid polymorphism in different ways depending on the mixtures of acidic lipids.
authors.affiliation: Laboratoire de Chimie Organique Biologique, URA CNRS 493, Université P. et M. Curie, Paris, France.
authors.forename: J P
authors.initials: JP
authors.lastname: Berlose
authors.forename: O
authors.initials: O
authors.lastname: Convert
authors.forename: D
authors.initials: D
authors.lastname: Derossi
authors.forename: A
authors.initials: A
authors.lastname: Brunissen
authors.forename: G
authors.initials: G
authors.lastname: Chassaing
mesh_terms: D000595:Amino Acid Sequence; D051943:Antennapedia Homeodomain Protein; D001665:Binding Sites; D002942:Circular Dichroism; D018398:Homeodomain Proteins / Q000737:chemistry*; D008081:Liposomes; D009682:Magnetic Resonance Spectroscopy; D008823:Micelles; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000737:chemistry; D010446:Peptide Fragments / Q000737:chemistry*; D011485:Protein Binding; D017433:Protein Structure, Secondary; D013816:Thermodynamics; D014157:Transcription Factors
chemical_list: D051943:Antennapedia Homeodomain Protein; D018398:Homeodomain Proteins; D008081:Liposomes; D008823:Micelles; D009687:Nuclear Proteins; D010446:Peptide Fragments; D014157:Transcription Factors