酶催化介导的点击标记策略：细菌糖基化末端N-乙酰半乳糖的靶向多维检测

原核细菌糖基化在致病菌侵染宿主细胞过程中扮演着重要角色。但是，相比于真核细胞糖基化系统深入的研究，细菌糖基化的研究尚显不足：不论是涉及的细菌种类还是糖苷单元和它们组成的糖链结构；这主要是因为细菌本身的特点，另一方面，胜任细菌糖基化研究的分析技术和方法有待进一步发展。本项目针对细菌表面糖基化糖链末端N-乙酰半乳糖（GalNAc）开展研究，发展适于细菌糖基化研究的检测方法学；设计集成靶向基团/报告元素/荧光基团/生物富集基团于一体的多功能标签分子，构建基于酶催化介导和点击偶联标记的靶向多维分析平台（元素质谱/荧光成像/生物质谱），研究GalNAc的含量、动态分布和所处糖链结构与致病菌侵染能力之间的关系。可以预期，针对GalNAc建立的靶向多维测量平台将深化对细菌致病机制的理解，也将撬动细菌其他种类糖基化研究的开展，为基于糖苷的抗生素药物的设计提供基础科学支撑。

Prokaryotic glycosylation plays a crucial role in the processes of bacterial infection towards their host cells. However, research on bacterial glycosylation is less investigated compared with the more extensive and/or intensive studies on eukaryotic glycosylation, considering either the bacterial species involved or the glycan-glycan structure clarified. Such outcomes are partly because of the intrinsic features of bacteria themselves and, more likely lack of capable analytical techniques and related methods. In this project, we aim to develop an analytical methodology that is capable for study of terminal N-Acetylgalactosamine (GalNAc) in the glycan structure on bacterial cell surface. We plan to design and synthesize a multifunctional labeling molecule that has targeting warhead, report element, fluorophore and bioconcentration moieties, thus based on the specificity of galactose oxidase catalysis and bio-orthogonal click reaction, a multidimensional analytical platform integrating, for example, elemental mass spectrometry, fluorescence imaging and biological mass spectrometry towards the terminal GalNAc can be established. On such a platform, study of the relationship between bacterial infection ability and the content, dynamic distribution of the terminal GalNAc and its linked glycan structure can be performed. It is expectable that the targeted multidimensional measurement platform established in this project will not only provide more information on understanding of GalNAc-mediated pathogenic mechanism of bacteria, but also will leverage the developments of research on other types of bacterial glycosylation, providing basic science support on the design of glycan-based novel antibiotics.