Sialidases as regulators of bioengineered cellular surfaces

Cell surface glycosylation plays a key role in regulating cellular interactions and signaling. Sialidases, or neuraminidases (NEUs), are enzymes that remove sialic acids from glycoproteins and glycolipids. While their general role in glycan turnover is established, their specific substrate preferences and functional outcomes remain unclear. Prior research has shown that sialic acid modifications can influence cell adhesion and signaling. However, the extent to which sialidases can accommodate unnatural sialic acid derivatives has not been fully explored. This uncertainty limits the design of glycoengineered cells and the development of sialidase inhibitors. No prior work had resolved how sialidases respond to structurally altered sialic acids. This gap motivated the current investigation into the substrate permissivity of cell-surface sialidases. Understanding this could improve the precision of glycoengineering and drug development. The study aimed to test whether sialidases can process unnatural sialic acids introduced via metabolic engineering.

The goal of this work was to assess the substrate flexibility of cell-surface sialidases toward unnatural sialic acid derivatives. Sialidases regulate glycan structures, which are critical for cell behavior. However, the extent to which these enzymes can tolerate structural modifications in sialic acids is unknown. The researchers sought to determine if sialidases can cleave unnatural sialic acids introduced into cells via glycoengineering. This knowledge could inform the design of glycoengineered cells and sialidase inhibitors. The study also aimed to evaluate how different R-group modifications on sialic acids affect sialidase activity. By using fluorogenic reporters, the team could directly measure sialidase activity on modified glycans. This approach allowed them to test a range of unnatural sialic acid derivatives. The findings could clarify the role of sialidases in glycoengineering and inhibitor development.

The researchers synthesized fluorogenic reporters of sialidase activity using unnatural sialic acids. These reporters were designed to be incorporated into cell surface glycans via metabolic glycoengineering. The study used Jurkat cells as a model system to assess sialidase activity. Cells were exposed to various sialic acid derivatives with different R-group modifications. Fluorogenic activity was measured to determine sialidase cleavage efficiency. The team tested a range of R-group substitutions, including bulky, hydrophobic, and fluorinated moieties. They used Jurkat cells because they express cell-surface sialidases. The experimental setup allowed for direct observation of sialidase activity on engineered glycans. By comparing cleavage rates across different sialic acid derivatives, the researchers could assess sialidase substrate permissivity.

The study found that Jurkat cell-surface sialidases can cleave unnatural sialic acids with varying efficiencies. Sialidases showed differential activity depending on the R-group modification of the sialic acid. Bulky, hydrophobic, and fluorinated moieties altered the structure-activity relationship of sialidase cleavage. Some modifications enhanced cleavage, while others reduced it. The results confirmed that sialidases can process unnatural sialic acids introduced via glycoengineering. The cleavage efficiency was not uniform across all R-group types, indicating substrate specificity. The fluorogenic reporters provided a direct measure of sialidase activity on modified glycans. These findings suggest that sialidases are flexible in their substrate tolerance. The study highlights the importance of glycan presentation in sialidase function.

The authors concluded that cell-surface sialidases are capable of cleaving unnatural sialic acids introduced via glycoengineering. The study revealed that sialidase activity is influenced by the R-group modifications on sialic acids. The differential cleavage rates suggest that sialidases have a degree of substrate flexibility. These findings support the idea that sialidases can accommodate structural variations in sialic acids. The results provide insights into the functional permissivity of sialidases in glycoengineering contexts. The study also highlights the importance of glycan presentation in sialidase binding and activity. The findings may inform the design of glycoengineered cells and sialidase inhibitors. The authors propose that these results could guide future efforts in metabolic glycoengineering and drug development.