Multidimensional NMR spectroscopy for the study of histone H4–Ni(ii) interaction

Abstract

The N-terminal 30-amino acid tail of histone H4, a nuclear protein, was studied as a model for the interaction of this protein with Ni(II) ions. The behaviour of the ends-blocked Ac-SGRGKGGKGLGKGGA₁₅K₁₆R₁₇H₁₈R₁₉KVLRDNIQGIT-Am fragment towards Ni(II) was analyzed with multidimensional NMR (1D, 2D TOCSY, NOESY) and UV-Vis spectroscopy. As expected, the coordination involved the imidazolic nitrogen of the His₁₈ residue and the three deprotonated amidic nitrogens of the His₁₈, Arg₁₇ and Lys₁₆ residues, respectively. A model for the structure of the complex was calculated from the inter-residual NOEs recorded in 2D NOESY spectra. The structure obtained shows that the interaction with the metal is responsible for deep changes in the conformation of the peptide, blocking the side chain of Arg₁₇ and Lys₁₆ residues above the coordination plane. These structural modifications may be physiologically relevant to the mechanism of nickel carcinogenesis.