The N- and C-Terminal Regions of the Pearl-Associated EF Hand Protein, PFMG1, Promote the Formation of the Aragonite Polymorph in Vitro
The N- and C-Terminal Regions of the Pearl-Associated EF Hand Protein, PFMG1, Promote the Formation of the Aragonite Polymorph in Vitro
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DOI：
10.1021/cg100363m
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发表时间：
2010-10-01
影响因子：
3.8
通讯作者：
Evans, John Spencer
中科院分区：
文献类型：
--
作者：
Amos, Fairland F.;Destine, Edly;Evans, John Spencer
最近的研究表明，软体动物贝壳珠层蛋白序列形成碳酸钙多晶体文石的能力，与这些蛋白内部存在内在无序的序列有关。虽然蛋白质结构紊乱和多态形成之间的确切关系尚不清楚，但人们对发现其他可以诱导文石形成的内在紊乱的珍珠层蛋白质序列的例子有明确的兴趣。在本报告中，我们将内在紊乱与文石形成之间的关系扩展到另一组珍珠层蛋白序列。这种被称为PFMG1的蛋白质与日本珍珠贝的珍珠形成有关。种fucata。我们证明了代表PFMG1的30个AA N和c端序列区域的合成肽在溶液中使纳米级文石成核，而无需额外的添加剂。与不含肽或牛血清白蛋白的对照相比，PFMG1末端序列似乎在形成生物矿物质的周围形成基质样环境，这一过程将在以后的报道中更详细地定义。此外，我们确定这些PFMG1末端序列在溶液中具有无序结构，可以使用结构稳定溶剂2,2,2-三氟乙醇稳定为部分折叠结构（螺旋结构，β结构）。虽然我们不知道这些肽在体外促进文石成核的机制，但我们认为这些末端序列是pfmg1介导的珍珠贝内文石多态形成的参与者，这些序列的内在无序性和折叠倾向对这种活性至关重要。
Recent studies indicate that the ability or mollusk shell nacre protein sequences to form the calcium carbonate polymorph, aragonite, are linked to the presence of intrinsically disordered sequences within these proteins. Although the exact relationship between protein structural disorder and polymorph formation is not clear, there is a definite interest in discovering other examples of intrinsically disordered nacre protein sequences that can induce aragonite formation. In this report, we extend the relationship between intrinsic disorder and aragonite formation to another set of nacre protein sequences. This protein, known as PFMG1, is associated with pearl formation in the Japanese pearl oyster. Pinctada fucata. We demonstrate that synthetic peptides representing the 30 AA N- and C-terminal sequence regions of PFMG1 nucleate nanoscale-sized aragonite in solution without the need for additional additives. Compared to controls containing no peptide or bovine serum albumin, the PFMG1 terminal sequences appear to form a matrix-like environment around the forming biominerals, and this process will he defined in more detail in later reports. Furthermore, we establish that these PFMG1 terminal sequences possess disordered structures in solution that can he stabilized into partially folded structures (a helix, beta structures) using the structure-stabilizing solvent, 2,2,2-trifluoroethanol. Although we do not know the mechanism by which these peptides promote aragonite nucleation in vitro, we believe that these terminal sequences are participants in PFMG1-mediated aragonite polymorph formation within the oyster pearl and that the intrinsic disorder and folding propensities of these sequences are crucial for this activity.