Molecular basis of tunable iridescence and excellent proton conductance of the reflectin assembly

反射蛋白是头足类动物中的一个大规模无序蛋白质家族，它们形成可调节的纳米组装体，使它们的体色能够瞬间改变。在体外，这些组件表现出极好的质子电导，可与最先进的人工材料相媲美。本计画将阐明反射光的可调颜色与极佳质子传导性的分子机制。这些知识将使合理设计的生物相容性人工材料的基础上可编程的光学和电学性能的反射。将培训多名本科生和一名研究生。PI将在当地K-12学校的推广活动中利用蛋白质的迷人性质，以促进STEM并激励下一代普通科学家和工程师。在同源反射中发现了几个保守的氨基酸序列，重现了全长蛋白质的特性。组装体中有序的分级结构和伴随的氢键网络是其有趣的光学和电学性质的主要原因。然而，亚基蛋白质的强烈紊乱禁止通过cryoEM或X射线衍射等技术在高分辨率下进行表征。该项目将应用固态NMR（ssNMR），这是非结晶样品的理想技术，以确定由一个称为（ref 2C）4的保守片段形成的组装体的原子结构模型。这些知识将解决悖论：如何在很大程度上无序亚基蛋白组装成有序布拉格反射器在光波长尺度调制光学特性。进一步的ssNMR实验将进行探测质子扩散的组装，这将解剖分子基序在一个残基特定的分辨率负责出色的质子导电性。这一建议是共同资助的材料研究部（MPS/DMR），化学，生物工程，环境，和运输系统（ENG/CBET）和分子和细胞生物科学部（BIO/MCB）该奖项反映了NSF的法定使命，并通过使用基金会的知识价值和更广泛的影响审查标准进行评估，被认为值得支持。

Reflectins are a family of largely-disordered proteins in cephalopods that form tunable nano-assemlies to enable instantaneous change of their body color. In vitro these assemblies exhibit superb protonic conductance, comparable to the-state-of-the-art artificial materials. This project will elucidate the molecular mechanism underpinning the tunable coloration and superb protonic conductivity of reflectins. This knowledge will enable rational design of bio-compatible artificial materials based on reflectins with programmable optical and electrical properties. Multiple undergraduates and one graduate will be trained. The PI will exploit the fascinating nature of the protein in his outreach activities for local K-12 schools to promote STEM and to inspire next general scientists and engineers.Several conserved amino acid sequences were found in homologous reflectins, recapitulating the properties of the full-length proteins. The intriguing optical and electrical properties were attributed to the ordered hierarchical structures and accompanied hydrogen bonding network in assemblies. However, the strong disorder of subunit proteins prohibits characterization at high resolution by techniques such as cryoEM or X-ray diffraction. This project will apply solid state NMR (ssNMR), the ideal technique for noncrystalline sample, to determine the atomic structural model of the assembly formed by one of the conserved fragments called (ref2C)4. This knowledge will resolve the paradox: how largely disordered subunit proteins assemble into ordered Bragg reflectors at light wavelength scale to modulate optical properties. Further ssNMR experiments will be performed to probe proton diffusion in the assembly, which will dissect the molecular motif at a residue-specific resolution responsible for the outstanding protonic conductivity.This proposal is co-funded by Division of Materials Research (MPS/DMR), Division of Chemical, Bioengineering, Environmental, and Transport Systems (ENG/CBET) and Division of Molecular and Cellular Biosciences (BIO/MCB).This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.