Multifunctional Proximity Labeling Strategy for Lipid Raft-Specific Sialic Acid Tracking and Engineering

Lipid raft-specific glycosylation has been implicated in many biological processes, including intracellular trafficking, cell adhesion, signal transduction, and host-pathogen interactions. The major predicament in lipid raft-specific glycosylation research is the unavailability of tools for tracking and manipulating glycans on lipid rafts at the microstructural level. To overcome this challenge, we developed a multifunctional proximity labeling (MPL) platform that relies on cholera toxin B subunit to localize horseradish peroxidase on lipid rafts. In addition to the prevailing electron-rich amino acids, modified sialic acid was included in the horseradish peroxidase-mediated proximity labeling substrate via purposefully designed chemical transformation reactions. In combination with sialic acid editing, the self-renewal of lipid raft-specific sialic acid was visualized. The MPL method enabled tracking of lipid raft dynamics under methyl-β-cyclodextrin and mevinolin treatments; in particular, the alteration of lipid rafts markedly affected cell migration. Furthermore, we embedded functional molecules into the method and implemented raft-specific sialic acid gradient engineering. Our novel strategy presents opportunities for tailoring lipid raft-specific sialic acids, thereby regulating interactions associated with lipid raft regions (such as cell-virus and cell-microenvironment interactions), and can aid in the development of lipid raft-based therapeutic regimens for tumors.