Cellular and Molecular Engineering of Glycan Sialylation in Heterologous Systems

Abstract

Glycans have been shown to play a key role in many biological processes, such as signal transduction, immunogenicity, and disease progression. Among the various glycosylation modifications found on cell surfaces and in biomolecules, sialylation is especially important, because sialic acids are typically found at the terminus of glycans and have unique negatively charged moieties associated with cellular and molecular interactions. Sialic acids are also crucial for glycosylated biopharmaceutics, where they promote stability and activity. In this regard, heterogenous sialylation may produce variability in efficacy and limit therapeutic applications. Homogenous sialylation may be achieved through cellular and molecular engineering, both of which have gained traction in recent years. In this paper, we describe the engineering of intracellular glycosylation pathways through targeted disruption and the introduction of carbohydrate active enzyme genes. The focus of this review is on sialic acid-related genes and efforts to achieve homogenous, humanlike sialylation in model hosts. We also discuss the molecular engineering of sialyltransferases and their application in chemoenzymatic sialylation and sialic acid visualization on cell surfaces. The integration of these complementary engineering strategies will be useful for glycoscience to explore the biological significance of sialic acids on cell surfaces as well as the future development of advanced biopharmaceuticals.

Expression Patterns of Glycosylation Regulators Define Tumor Microenvironment and Immunotherapy in Gastric Cancer

“…More than half of the proteins in organisms have glycosylation modification, including transcription factors and metabolism-related enzymes ( Ferreira et al, 2021 ; Sun et al, 2021 ; Zheng et al, 2021 ). Glycosylation modification affects protein spatial conformation, activity, transportation, and positioning and is widely involved in intercellular recognition, regulation, and signal transduction ( Hombu et al, 2021 ). Protein glycosylation has been proved to play an important role in the occurrence and progression of various metabolic diseases ( Dozio et al, 2021 ) and malignant tumor diseases ( Reily et al, 2019 ).…”

Redirection of CAR-T Cell Cytotoxicity Using Metabolic Glycan Labeling with Unnatural Sugars

“…However, flow cytometry analysis revealed that Ac 4 ManN-DNP treatment also failed to yield the surface presentation of glycans modified with DNP hapten on cancer cells, unlike the two-step labeling with Ac 4 ManNAz and DBCO-DNP (Figure 4e). A series of enzymatic reactions are required to convert the derivatives of ManNAc into sialic acids, which are then incorporated into the nonreducing termini of N-glycans 23 (Figure 5a). Given that our above-described results suggested that hapten-modified ManNAc derivatives may not be suitable substrates for the initial enzymatic reactions, we synthesized two hapten-conjugated sialic acid derivatives, fluorescein isothiocyanate-conjugated sialic acid (Sia-FITC) and dinitrophenyl-conjugated sialic acid (Sia-DNP), 24,25 (Figure 5b,c) to bypass the initial enzymatic steps.…”

Protein structure, a genetic encoding for glycosylation

“…Similarly, low fulfillment is seen in high-yield expression systems 87 necessitating, in some cases, supplementation with maturing glycoenzymes. 88–90…”