Complex carbohydrates (often called “glycans”) are one of four major building blocks of life, playing  crucial roles in numerous biological processes. Almost all vertebrate cell surfaces are decorated with complex variations of sialoglycan structures terminating with a set of nine-carbon-backbone monosaccharides known as Sialic acids (Sias), which in turn display much diversity. Sialoglycans are important in diverse biological processes, including cell-cell interactions, immune regulation, cellular homeostasis, host-pathogen interactions and microbial pathogenesis. Characterization of the vast sialoglycome remains limited due to the lack of optimal tools and techniques. Although traditional glycomic methods are useful, methodologies for purification and analysis can disrupt or overlook crucial aspects of Sia diversity or fail to elucidate native structures as they exist in biological systems. The <i>in situ</i> detection and analysis of sialoglycans has largely relied on plant lectins or antibodies whose specificities are limited and/or uncertain. Meanwhile, host-pathogen-commensal interactions have already evolved specific Sialoglycan-binding preferences of various bacterial adhesins, toxin subunits and viral hemagglutinin-esterases. We took advantage of such molecules to develop a series of Sialoglycan Recognizing Probes (SGRPs) to provide a convenient and systematic approach to investigate the mammalian sialoglycome. Key residues in the binding pocket of each probe were mutated to provide their respective nonbinding controls. We used a sialoglycan microarray consisting of more than 200 defined sialoglycans to define the binding specificities of the SGRPs. Further optimization for practical applications is being performed by applying the probes towards ELISA, Western Blot, FACS analysis and immunohistochemistry. While further work is needed to define a comprehensive suite of SGRPs, our current efforts provide a reliable toolkit with high order of specificity to track the dynamic mammalian sialoglycome, an approach requiring little or no experience in glycan chemistry or analysis.

Sialoglycan recognizing probes (SGRPs): Toolkit for precise probing of the dynamic mammalian sialoglycome

2019 Fall National Meeting

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