Center for Craniofacial Molecular Biology, Department of Biomedical Sciences, Herman Ostrow School of Dentistry, University of Southern California, Los Angeles, CA 90033, USA.
Department of Neuroscience and Physiology, Department of Biochemistry and Molecular Medicine, Zilkha Neurogenetic Institute, Keck School of Medicine, University of Southern California, Los Angeles, CA 90033, USA.
Int J Mol Sci. 2023 Feb 9;24(4):3484. doi: 10.3390/ijms24043484.
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.
釉基质蛋白 ameloblastin（Ambn）具有关键的生理功能，包括调节矿化、细胞分化和细胞-基质黏附。我们研究了 Ambn 在与靶标相互作用过程中的局部结构变化。我们进行了生物物理测定，并使用脂质体作为细胞膜模型。xAB2N 和 AB2 肽是经过合理设计的，包含了 Ambn 中包含自组装和含有螺旋的膜结合基序的区域。对自旋标记肽的电子顺磁共振（EPR）研究表明，在脂质体、釉原蛋白（Amel）和 Ambn 存在的情况下，局部结构得到了增强。囊泡清除和渗漏实验表明，肽-膜相互作用与肽自组装无关。色氨酸荧光和 EPR 表明 Ambn-Amel 和 Ambn-膜相互作用之间存在竞争。我们通过跨越小鼠 Ambn 57 到 90 位残基的多靶向结构域，证明了 Ambn 在与不同靶标相互作用时会发生局部结构变化。Ambn 与不同靶标相互作用后的结构变化，对 Ambn 在釉质形成中的多功能性具有重要意义。
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