Control of calcium oxalate crystal growth by face-specific adsorption of an osteopontin phosphopeptide
Control of calcium oxalate crystal growth by face-specific adsorption of an osteopontin phosphopeptide
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DOI：
10.1021/ja0745613
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发表时间：
2007-12-05
影响因子：
15
通讯作者：
Hunter, Graeme K.
中科院分区：
文献类型：
--
作者：
Grohe, Bernd;O'Young, Jason;Hunter, Graeme K.
矿物相关蛋白质被认为可以调节生物矿化的许多方面，包括晶体的位置、类型、取向、形状和纹理。为了了解蛋白质如何达到这种精细的控制水平，我们正在研究磷蛋白骨桥蛋白（OPN）和生物矿物草酸钙一水合物（COM）之间的相互作用。在本研究中，我们已经合成了对应于大鼠骨OPN（pSHEpSTEQSDAIDpSAEK）的氨基酸220-235的肽，所述氨基酸220 - 235是在蛋白质中发现的几个高度磷酸化的、富含天冬氨酸和谷氨酸的序列之一。为了研究磷酸化在与晶体相互作用中的作用，制备了不含（P0）、含一种（P1）或含所有三种（P3）磷酸盐的肽。使用共聚焦显微镜和扫描电子显微镜的一种新的组合，我们表明，这些肽优先吸附到COM的{100}面，并抑制这些面在磷酸化依赖的方式增长。为了表征OPN肽吸附到COM的机制，我们进行了蛋白质-晶体相互作用的第一个原子尺度的分子动力学模拟。P3吸附到{100}面比P1快得多，P1又比PO吸附得快。在所有情况下，天冬氨酸和谷氨酸，而不是磷酸丝氨酸，是与晶体表面接触最密切的氨基酸。这些研究已经确定了骨桥蛋白中的COM面特异性吸附基序，并描绘了羧酸盐和磷酸盐基团在矿物相关磷蛋白抑制晶体生长中的单独作用。我们建议，形成近距离，稳定，和面对特定的相互作用是磷蛋白的能力，以调节生物矿化过程中的一个关键因素。
Mineral-associated proteins have been proposed to regulate many aspects of biomineralization, including the location, type, orientation, shape, and texture of crystals. To understand how proteins achieve this exquisite level of control, we are studying the interaction between the phosphoprotein osteopontin (OPN) and the biomineral calcium oxalate monohydrate (COM). In the present study, we have synthesized peptides corresponding to amino acids 220-235 of rat bone OPN (pSHEpSTEQSDAIDpSAEK), one of several highly phosphorylated, aspartic-, and glutamic acid-rich sequences found in the protein. To investigate the role of phosphorylation in interaction with crystals, peptides containing no (P0), one (P1), or all three (P3) phosphates were prepared. Using a novel combination of confocal microscopy and scanning electron microscopy, we show that these peptides adsorb preferentially to {100} faces of COM and inhibit growth of these faces in a phosphorylation-dependent manner. To characterize the mechanism of adsorption of OPN peptides to COM, we have performed the first atomic-scale molecular-dynamics simulation of a protein-crystal interaction. P3 adsorbs to the {100} face much more rapidly than P1, which in turn adsorbs more rapidly than PO. In all cases, aspartic and glutamic acid, not phosphoserine, are the amino acids in closest contact with the crystal surface. These studies have identified a COM face-specific adsorption motif in OPN and delineated separate roles for carboxylate and phosphate groups in inhibition of crystal growth by mineral-associated phosphoproteins. We propose that the formation of close-range, stable, and face-specific interactions is a key factor in the ability of phosphoproteins to regulate biomineralization processes.