A solution NMR investigation into the impaired self-assembly properties of two murine amelogenins containing the point mutations T21→I or P41→T.
A solution NMR investigation into the impaired self-assembly properties of two murine amelogenins containing the point mutations T21→I or P41→T.
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DOI：
10.1016/j.abb.2013.07.015
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发表时间：
2013-09-15
影响因子：
3.9
通讯作者：
Shaw WJ
中科院分区：
文献类型：
--
作者：
Buchko GW;Lin G;Tarasevich BJ;Shaw WJ
牙釉质发生障碍描述了一组导致牙釉质缺陷的遗传性疾病。与人类釉质形成相关的两种疾病是釉原蛋白的点突变T21→I或P40→T，釉原蛋白是在釉质生物矿化的早期阶段存在于成釉细胞中的主要蛋白质。通过核磁共振波谱法探测野生型鼠釉原蛋白（M180）和两种含有鼠釉原蛋白中的等同突变的蛋白质T21→I（M180-I）和P41→T（M180-T）的生物物理性质。在低蛋白浓度（0.1 mM）下，M180、M180-I和M180-T在pH 3.0的2%乙酸中主要是单体，并且两种突变都不产生主要的结构变化。作为蛋白质（0.1至1.8 mM）和NaCl（0至400 mM）浓度的函数的化学位移扰动研究表明，相对于野生型釉原蛋白，突变通过在较低的蛋白质或盐浓度下引起自组装来影响自缔合特性，其中观察到的M180-I的影响最大。在这两种条件下，过早的自组装开始附近的N-末端，提供了进一步的证据，该区域在自组装过程中的重要性。与野生型M180相比，M180-I和M180-T在较低的蛋白质浓度和较低的离子强度下的自缔合可以解释这些突变的临床表型，即有缺陷的釉质形成。
Amelogenesis imperfecta describes a group of inherited disorders that results in defective tooth enamel. Two disorders associated with human amelogenesis imperfecta are the point mutations T21→I or P40→T in amelogenin, the dominant protein present in ameloblasts during the early stages of enamel biomineralization. The biophysical properties of wildtype murine amelogenin (M180) and two proteins containing the equivalent mutations in murine amelogenin, T21→I (M180-I) and P41→T (M180-T), were probed by NMR spectroscopy. At low protein concentration (0.1 mM) M180, M180-I, and M180-T are predominately monomeric at pH 3.0 in 2% acetic acid and neither mutation produces a major structural change. Chemical shift perturbation studies as a function of protein (0.1 to 1.8 mM) and NaCl (0 to 400 mM) concentration show that the mutations affect the self-association properties by causing self-assembly at lower protein or salt concentrations, relative to wildtype amelogenin, with the largest effect observed for M180-I. Under both conditions, the premature self-assembly is initiated near the N-terminus, providing further evidence for the importance of this region in the self-assembly process. The self-association of M180-I and M180-T at lower protein concentrations and lower ionic strengths than wildtype M180 may account for the clinical phenotypes of these mutations, defective enamel formation.