title: Does tetracycline bind helix 2 of prion? An integrated spectroscopical and computational study of the interaction between the antibiotic and alpha helix 2 human prion protein fragments.
abstract: We demonstrate here that tetracycline (TC) can strongly interact (KD' = 189 +/- 7 nM) with model peptides derived from the C-terminal globular domain of the prion protein, hPrP [173-195], and that interaction concerns residues within the C-terminal half of the helix 2, a short region previously indicated as endowed with ambivalent conformational behavior and implicated in PrP conversion to the beta-sheet-rich, infective scrapie variant. Data have been confirmed by binding studies with the N-terminal truncated 180-195 variant that displays a dissociation constant of 483 +/- 30 nM. Remarkably, TC does not influence the structure of the N-terminally fluoresceinated peptides that both show alpha-helical conformations. Docking calculations and molecular dynamics simulations suggest a direct, strong interaction of the antibiotic with exposed side chain functional groups of threonines 190-193 on the solvent-exposed surface of helix 2.
authors.affiliation: Istituto di Biostrutture e Bioimmagini del CNR, Sezione Biostrutture, via Mezzocannone 16, 80134 Napoli, Italy.
authors.forename: Luisa
authors.initials: L
authors.lastname: Ronga
authors.forename: Emma
authors.initials: E
authors.lastname: Langella
authors.forename: Pasquale
authors.initials: P
authors.lastname: Palladino
authors.forename: Daniela
authors.initials: D
authors.lastname: Marasco
authors.forename: Barbara
authors.initials: B
authors.lastname: Tizzano
authors.forename: Michele
authors.initials: M
authors.lastname: Saviano
authors.forename: Carlo
authors.initials: C
authors.lastname: Pedone
authors.forename: Roberto
authors.initials: R
authors.lastname: Improta
authors.forename: Menotti
authors.initials: M
authors.lastname: Ruvo
mesh_terms: D000595:Amino Acid Sequence; D000900:Anti-Bacterial Agents / Q000737:chemistry; D002942:Circular Dichroism; D006801:Humans; D007700:Kinetics; D008969:Molecular Sequence Data; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry / Q000302:isolation & purification; D011328:Prions / Q000737:chemistry / Q000378:metabolism*; D011485:Protein Binding; D011487:Protein Conformation; D012997:Solvents; D013050:Spectrometry, Fluorescence; D013752:Tetracycline / Q000737:chemistry / Q000378:metabolism*
chemical_list: D000900:Anti-Bacterial Agents; D010455:Peptides; D011328:Prions; D012997:Solvents; D013752:Tetracycline