Involvement of histidines 11, 15 and 19 in the binding of zinc to the fusogenic H5WYG peptide

摘要

The histidine-rich GLFHAIAHFIHGGWHGLIHGWYG peptide (H5WYG) coordinates a Zn2+ ion and forms a stable peptide-metal complex promoting membrane fusion at physiologic pH. In our previous article titled 'Histidine-rich peptide: evidence for a single zinc-binding site on H5WYG peptide that promotes membrane fusion at neutral pH' in Journal of Mass Spectrometry (2009, 44,81-89), tandem mass spectrometry experiments have provided evidence for the binding of a single Zn2+ ion to H5WYG and suggested that this binding is shared between H-11, H-19 and probably H-15 residues. To clarify the involvement of these histidine residues in the binding to the Zn2+ ion and especially to remove the doubt about the implication of the H-15 residue, here we have used three H5WYG mutants termed H5WYGH11A, H5WYGH15A and H5WYGH19A, whose H-11, H-15 and H-19 residues were replaced with an alanine residue. The novelty introduced by these new tandem mass spectrometry experiments performed with the mutants is the demonstration that H-15 is involved in the binding of the single Zn2+ ion and that it may even favour the setting of another Zn2+ ion. Thus, the three histidines H-11, H-15 and H-19 could lead to a specific structuring of H5WYG that can promote membrane fusion upon the binding of zinc.