Lee So Young, Marando Victoria M, Smelyansky Stephanie R, Kim Daria E, Calabretta Phillip J, Warner Theodore C, Bryson Bryan D, Kiessling Laura L
Department of Chemistry, Massachusetts Institute of Technology, Cambridge, Massachusetts 02139, United States.
Department of Chemistry, University of Wisconsin Madison, Madison, Wisconsin 53706, United States.
J Am Chem Soc. 2024 Jan 10;146(1):377-385. doi: 10.1021/jacs.3c09495. Epub 2023 Dec 19.
() is one of history's most successful human pathogens. By subverting typical immune responses, can persist within a host until conditions become favorable for growth and proliferation. Virulence factors that enable mycobacteria to modulate host immune systems include a suite of mannose-containing glycolipids: phosphatidylinositol mannosides, lipomannan, and lipoarabinomannan (LAM). Despite their importance, tools for their covalent capture, modification, and imaging are limited. Here, we describe a chemical biology strategy to detect and visualize these glycans. Our approach, biosynthetic incorporation, is to synthesize a lipid-glycan precursor that can be incorporated at a late-stage step in glycolipid biosynthesis. We previously demonstrated selective mycobacterial arabinan modification by biosynthetic incorporation using an exogenous donor. This report reveals that biosynthetic labeling is general and selective: it allows for cell surface mannose-containing glycolipid modification without nonspecific labeling of mannosylated glycoproteins. Specifically, we employed azido-()-farnesyl phosphoryl-β-d-mannose probes and took advantage of the strain-promoted azide-alkyne cycloaddition to label and directly visualize the localization and dynamics of mycobacterial mannose-containing glycolipids. Our studies highlight the generality and utility of biosynthetic incorporation as the probe structure directs the selective labeling of distinct glycans. The disclosed agents allowed for direct tracking of the target immunomodulatory glycolipid dynamics in cellulo. We anticipate that these probes will facilitate investigating the diverse biological roles of these glycans.
（某病原体）是历史上最成功的人类病原体之一。通过颠覆典型的免疫反应，（该病原体）能够在宿主体内持续存在，直至条件有利于其生长和增殖。使分枝杆菌能够调节宿主免疫系统的毒力因子包括一系列含甘露糖的糖脂：磷脂酰肌醇甘露糖苷、脂甘露聚糖和脂阿拉伯甘露聚糖（LAM）。尽管它们很重要，但用于其共价捕获、修饰和成像的工具却很有限。在这里，我们描述了一种化学生物学策略来检测和可视化这些聚糖。我们的方法，即生物合成掺入，是合成一种脂质 - 聚糖前体，该前体可以在糖脂生物合成的后期步骤中掺入。我们之前使用外源性供体通过生物合成掺入证明了分枝杆菌阿拉伯聚糖的选择性修饰。本报告表明生物合成标记具有通用性和选择性：它允许对细胞表面含甘露糖的糖脂进行修饰，而不会对甘露糖基化糖蛋白进行非特异性标记。具体而言，我们使用了叠氮基 - （某物质） - 法尼基磷酸 - β - D - 甘露糖探针，并利用应变促进的叠氮化物 - 炔烃环加成来标记并直接可视化分枝杆菌含甘露糖的糖脂的定位和动态。我们的研究强调了生物合成掺入的通用性和实用性，因为探针结构指导了对不同聚糖的选择性标记。所公开的试剂允许在细胞内直接追踪目标免疫调节糖脂的动态。我们预计这些探针将有助于研究这些聚糖的多种生物学作用。
