Sequence-Defined Energetic Shifts Control the Disassembly Kinetics and Microstructure of Amelogenin Adsorbed onto Hydroxyapatite (100).
Sequence-Defined Energetic Shifts Control the Disassembly Kinetics and Microstructure of Amelogenin Adsorbed onto Hydroxyapatite (100).
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DOI：
10.1021/acs.langmuir.5b02549
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发表时间：
2015-09-29
期刊：
影响因子：
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通讯作者：
Tarasevich BJ
中科院分区：
文献类型：
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作者：
Tao J;Buchko GW;Shaw WJ;De Yoreo JJ;Tarasevich BJ
蛋白质与表面之间的相互作用对许多重要过程至关重要，包括生物矿化、生物材料的生物相容性和生物传感器的功能。虽然许多蛋白质以单体或小寡聚体形式存在，但釉原蛋白是一种独特的蛋白质，其自组装成称为“纳米球”的超分子结构，即直径为20-60 nm的数百个单体的聚集体。在溶液中观察到纳米球四级结构;然而，吸附到羟基磷灰石（HAP）表面上的釉原蛋白的四级结构是未知的，即使它可能对釉原蛋白在釉质形成期间形成高度伸长和复杂组装的HAP微晶的功能是重要的。我们报告的相互作用的釉蛋白，釉原蛋白（rpM 179），与一个定义明确的（100）面制备的大晶体的HAP的合成的研究。高分辨率原位原子力显微镜（AFM）被用来直接观察蛋白质吸附到HAP在分子水平上的水溶液环境中。我们的研究表明，釉原蛋白纳米球分解到HAP表面，分解成更大的纳米球的寡聚体（25聚体）亚基。在某些情况下，拆卸事件是第一次直接观察到的原位成像。通过尺寸分析对吸附物量进行定量，确定了与HAP（100）特定表面的蛋白质结合能（17.1kbT）。拆解的动力学在老化溶液中大大减慢，表明纳米球内的寡聚体-寡聚体结合相互作用存在时间依赖性增加。通过将组氨酸标签连接到rpM 179的N-末端以形成rp（H）M180，釉原蛋白序列的微小变化导致在下面的第一层的顶部上吸附完整的第二层。我们的研究阐明了超分子蛋白质结构如何相互作用并在表面分解，以及釉原蛋白一级序列的微小变化如何影响分解过程。
The interactions between proteins and surfaces are critical to a number of important processes including biomineralization, the biocompatibility of biomaterials, and the function of biosensors. Although many proteins exist as monomers or small oligomers, amelogenin is a unique protein that self-assembles into supramolecular structures called “nanospheres,” aggregates of hundreds of monomers that are 20–60 nm in diameter. The nanosphere quaternary structure is observed in solution; however, the quaternary structure of amelogenin adsorbed onto hydroxyapatite (HAP) surfaces is not known even though it may be important to amelogenin’s function in forming highly elongated and intricately assembled HAP crystallites during enamel formation. We report studies of the interactions of the enamel protein, amelogenin (rpM179), with a well-defined (100) face prepared by the synthesis of large crystals of HAP. High-resolution in situ atomic force microscopy (AFM) was used to directly observe protein adsorption onto HAP at the molecular level within an aqueous solution environment. Our study shows that the amelogenin nanospheres disassemble onto the HAP surface, breaking down into oligomeric (25-mer) subunits of the larger nanosphere. In some cases, the disassembly event is directly observed by in situ imaging for the first time. Quantification of the adsorbate amounts by size analysis led to the determination of a protein binding energy (17.1kbT) to a specific face of HAP (100). The kinetics of disassembly are greatly slowed in aged solutions, indicating that there are time-dependent increases in oligomer–oligomer binding interactions within the nanosphere. A small change in the sequence of amelogenin by the attachment of a histidine tag to the N-terminus of rpM179 to form rp(H)M180 results in the adsorption of a complete second layer on top of the underlying first layer. Our research elucidates how supramolecular protein structures interact and break down at surfaces and how small changes in the primary sequence of amelogenin can affect the disassembly process.