We previously showed that the metal-binding domain 1-16 of intact amyloid-beta (Aβ) is involved in interactions with a number of proteins from the cytosolic fraction of SK-N-SH human neuroblastoma cells in a zinc-dependent manner only. It is known that hereditary mutations in the Aβ metal-binding domain (Aβ(1-16)), which accelerate the development of Alzheimer's disease and post-translational modifications of amino acid residues, can significantly affect the domain's structure in the presence of zinc ions. In this work, using the molecular fishing methodology for Aβ(l-16) isoforms with the Taiwanese mutation (D7H) and a phosphorylated Ser8 residue, proteins from the cytosol of SK-N-SH cells were found that are able to form zinc-dependent non-covalent complexes with these domains. The partner proteins identified for these isoforms differed from those for intact Aβ(1-16). In contrast, the Aβ(1-16) isoform with the English mutation (H6R) and the Aβ(1-16) isoform containing both an isomerized Asp7 residue and phosphorylated Ser8 residue did not interact with cytosolic proteins. The results are useful for developing methods for rational modulation of protein-protein interactions involving natural isoforms of beta-amyloid, and also indicate the possible role of beta-amyloid with phosphorylated Ser8 as a molecule involved in normal physiological processes.
Keywords: Alzheimer's disease; SK-N-SH cells; amyloid-beta; isoforms; metal-binding domain; protein-protein interactions; zinc.