9-Azido Analogues of Three Sialic Acid Forms for Metabolic Remodeling of Cell-Surface Sialoglycans

Abstract

Neu5Ac, Neu5Gc, and KDN are three forms of sialic acids in vertebrates that possess distinct biological functions. Herein, we report the synthesis and metabolic incorporation of the 9-azido analogues of three sialic acid forms in mammalian cells. The incorporated sialic acid analogues enable fluorescent imaging of cell-surface sialoglycans and proteomic profiling of sialoglycoproteins. Furthermore, we apply them to metabolically engineer cell surfaces with sialoglycans terminated with distinct sialic acids or their 9-azido analogues. The remodeled cells expressing specific cell-surface sialoglycoforms show distinct binding affinity toward subtilase cytotoxin (SubAB), a toxin secreted by Shiga toxigenic Escherichia coli. The 9-azido analogues of sialic acid forms developed in this work provide a versatile tool for metabolic remodeling of cell-surface properties and modulating pathogen–host interactions.

In Situ Determination of Sialic Acid on Cell Surface with a pH-Regulated Polymer Enzyme Nanoreactor

“…Also, the SA expression on A549 cells was higher than that on HeLa cells, which was in good agreement with the previous reports (Table S2). [6][7][8]20 Furthermore, the SA expression on the surface of HepG2 was in good agreement with the data obtained using the commercial SA kit (4.7 nmol in 1 × 10 6 cells).…”

“…5,6 SA usually presents on the cell surface as sialoglycoconjugates, such as sialylated proteins and lipids. 7 Traditional SA sensing strategies, including mass spectrometry, 8 plasmon resonance, 9,10 colorimetric methods, 11,12 liquid chromatography, 13 electrochemical sensing, 14,15 and fluorescence analysis 16−20 have limitations for in situ analysis applications. The most frequently used SA analysis approach focuses on the separation and extraction of SA-terminated glycopeptides, enzymolysis, and liquid chromatography-mass spectrometric analysis.…”

“…Sialic acid (SA), or N -acetyl neuraminic acid, is a nine-carbon acidic monosaccharide. It is known to be an indicator for some cancers owing to its overexpression on cell surfaces. − SA on the outermost cell surface is involved in cellular communication and the key points of the immune system, which has been studied for exploitation in tumor therapies. , SA usually presents on the cell surface as sialoglycoconjugates, such as sialylated proteins and lipids . Traditional SA sensing strategies, including mass spectrometry, plasmon resonance, , colorimetric methods, , liquid chromatography, electrochemical sensing, , and fluorescence analysis − have limitations for in situ analysis applications.…”

Chemical labeling and analysis of sialoglycans

“…图 5 新型非天然唾液酸的开发及应用. (a) 9AzNeu5Ac、9AzNeu5Gc和9AzKDN是对应3种唾液酸亚型的非天然唾液酸, 实现了唾液酸亚型特 异的生物正交标记 [71] . (b) 双功能唾液酸9AzSiaNDAz和9AzSiaNAl, 可分别用于唾液酸结合蛋白的鉴定和唾液酸化聚糖的双色成像 [72] .…”

“…Development and application of novel unnatural sialic acids. (a) 9-Azido analogues of three sialic acid forms, 9AzNeu5Ac, 9AzNeu5Gc and 9AzKDN, enable metabolic labeling of specific sialoglycoforms[71] …”