2D MEMBRANE PROTEIN CRYSTALLIZATION USING DNA TEMPLATE

本子项目是利用由NIH/NCRR资助的中心赠款提供的资源的众多研究子项目之一。子项目和研究者（PI）可能已经从另一个NIH来源获得了主要资金，因此可以在其他CRISP条目中表示。列出的机构是中心的，不一定是研究者的机构。我们的目标是使用自组装的二维（2D） DNA晶格来指导膜蛋白的周期性组装，以获得高质量的晶体。近年来，冷冻电镜晶体学已被用于从蛋白质分子的二维晶体中获得高分辨率结构，前提是可以获得高质量的二维晶体。目前，大分子的二维结晶方法严重依赖于蛋白质分子表面之间不可预测的相互作用（例如疏水和静电相互作用）。已经开发出使用生物素标记或镍螯合脂质将链亲和素或组氨酸标记的蛋白质组织成二维晶体的方法。然而，在这些设计中，控制蛋白质分子的间距或周期性仍然很难控制。这种控制是组织不同维度的蛋白质所必需的。通过结合Allen在3D膜晶体学方面的专业知识和Yan在DNA自组装方面的专业知识，我们建议开发一种强大的模块化技术，利用自组装的二维DNA晶格将跨膜蛋白质组织成周期性的二维晶体。这种模块化技术将使我们能够合理地将感兴趣的蛋白质组织成有序的二维晶体，这将有助于利用冷冻电子显微镜研究阐明其分子结构。膜蛋白的结构研究将有助于我们了解细胞膜的功能，并将对设计跨膜给药产生重大影响。

This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. Our goal is to use self-assembled two-dimensional (2D) DNA lattices to direct periodic assembly of membrane proteins to obtain high quality crystals. In recent years, cryo-EM crystallography has been used to obtain high-resolution structures from 2D crystals of protein molecules provided that quality 2D crystals can be achieved. Currently the methods for 2D crystallization of macromolecules heavily rely on unpredictable interaction between the surfaces of the protein molecules (e.g. hydrophobic and electrostatic interaction). Methods have been developed to use biotin-tagged or nickel chelated lipids to organize streptavidin or histidine-tagged proteins into 2D crystal. However, controlled spacing or periodicity of the protein molecule is still hard to control in these designs. Such control is needed to organize proteins of various dimensions. By combining the expertise from Allen on 3D membrane crystallography and Yan on DNA self-assembly, we propose to develop a robust and modular technology to use self-assembled 2D DNA lattices to organize transmembrane proteins into periodical 2D crystals. This modular technology will enable us to rationally organize the protein of interest into an ordered 2D crystal which will facilitate the elucidation of their molecular structures using cryo-electron microscopy studies. Structural studies of membrane proteins will help us understand cellular membrane functions and will have significant impact in designing drug delivery across the membrane.