The Dynamic Interactions of a Multitargeting Domain in Ameloblastin Protein with Amelogenin and Membrane

Abstract

The enamel matrix protein Ameloblastin (Ambn) has critical physiological functions, including regulation of mineral formation, cell differentiation, and cell–matrix adhesion. We investigated localized structural changes in Ambn during its interactions with its targets. We performed biophysical assays and used liposomes as a cell membrane model. The xAB2N and AB2 peptides were rationally designed to encompass regions of Ambn that contained self-assembly and helix-containing membrane-binding motifs. Electron paramagnetic resonance (EPR) on spin-labeled peptides showed localized structural gains in the presence of liposomes, amelogenin (Amel), and Ambn. Vesicle clearance and leakage assays indicated that peptide–membrane interactions were independent from peptide self-association. Tryptophan fluorescence and EPR showed competition between Ambn–Amel and Ambn–membrane interactions. We demonstrate localized structural changes in Ambn upon interaction with different targets via a multitargeting domain, spanning residues 57 to 90 of mouse Ambn. Structural changes of Ambn following its interaction with different targets have relevant implications for the multifunctionality of Ambn in enamel formation.

Revisiting ameloblastin; addressing the EMT-ECM axis above and beyond oral biology

“…Ameloblastin (AMBN) is a pleiotropic protein (Spoutil et al, 2023) previously assumed to be specifically expressed by ameloblasts and responsible for extracellular crystal formation of enamel during tooth development (Lacruz et al, 2017;Liang et al, 2019). While AMBNrelated research has primarily focused on dental tissues, potential AMBN functions in nonoral tissues and organs have been suggested Stakkestad et al, 2018;Kegulian et al, 2023). During embryonic development, it can be present in salivary glands (Sharifi et al, 2021) and also in adult adipose tissue (Stakkestad et al, 2018).…”