Rao Ashit, Roncal-Herrero Teresa, Schmid Elina, Drechsler Markus, Scheffner Martin, Gebauer Denis, Kröger Roland, Cölfen Helmut
Physical Chemistry, Department of Chemistry, University of Konstanz, Universitätsstr. 10, Konstanz 78464, Germany.
Faculty of Science and Technology, Physics of Complex Fluids, University of Twente, PO Box 217, Enschede 7500 AE, The Netherlands.
ACS Cent Sci. 2019 Feb 27;5(2):357-364. doi: 10.1021/acscentsci.8b00853. Epub 2019 Feb 1.
Cellular machineries guide the bottom-up pathways toward crystal superstructures based on the transport of inorganic precursors and their precise integration with organic frameworks. The biosynthesis of mesocrystalline spines entails concerted interactions between biomolecules and inorganic precursors; however, the bioinorganic interactions and interfaces that regulate material form and growth as well as the selective emergence of structural complexity in the form of nanostructured crystals are not clear. By investigating mineral nucleation under the regulation of recombinant proteins, we show that SpSM50, a matrix protein of the sea urchin spine, stabilizes mineral precursors via vesicle-confinement, a function conferred by a low-complexity, disordered region. Site-specific proteolysis of this domain by a collagenase initiates phase transformation of the confined mineral phase. The residual C-type lectin domain molds the fluidic mineral precursor into hierarchical mesocrystals identical to structural crystal modules constituting the biogenic mineral. Thus, the regulatory functions of proteolytic enzymes can guide biomacromolecular domain constitutions and interfaces, in turn determining inorganic phase transformations toward hybrid materials as well as integrating organic and inorganic components across hierarchical length scales. Bearing striking resemblance to biogenic mineralization, these hybrid materials recruit bioinorganic interactions which elegantly intertwine nucleation and crystallization phenomena with biomolecular structural dynamics, hence elucidating a long-sought key of how nature can orchestrate complex biomineralization processes.
细胞机制基于无机前体的运输及其与有机框架的精确整合，引导自下而上的途径形成晶体超结构。介晶刺的生物合成需要生物分子与无机前体之间的协同相互作用；然而，调节材料形态和生长以及以纳米结构晶体形式选择性出现结构复杂性的生物无机相互作用和界面尚不清楚。通过研究重组蛋白调控下的矿物成核过程，我们发现海胆刺的基质蛋白SpSM50通过囊泡限制作用稳定矿物前体，这一功能由一个低复杂性、无序区域赋予。胶原酶对该结构域进行位点特异性蛋白水解，引发受限矿物相的相变。残余的C型凝集素结构域将流体矿物前体塑造成与构成生物矿物的结构晶体模块相同的分级介晶。因此，蛋白水解酶的调节功能可以引导生物大分子结构域的组成和界面，进而决定向杂化材料的无机相变以及在分级长度尺度上整合有机和无机成分。这些杂化材料与生物矿化有着惊人的相似之处，它们利用生物无机相互作用，将成核和结晶现象与生物分子结构动力学巧妙地交织在一起，从而阐明了长期以来人们一直在寻找的关于自然如何协调复杂生物矿化过程的关键。
