Engineering of complex protein sialylation in plants

Area of Science:

• Biochemistry
• Glycobiology
• Plant Biotechnology

Background:

• Sialic acids (Sias) are crucial terminal glycans on proteins, with polysialic acid (polySia) playing diverse biological roles.
• Producing defined sialylated structures is challenging due to immense glycan diversity, hindering therapeutic development.

Purpose of the Study:

• To develop a plant-based expression system for controlled in vivo synthesis of defined sialylated structures.
• To enable precise investigation of sialic acid functions and facilitate rational glycan engineering for biotechnological applications.

Main Methods:

• Utilized a combination of stable plant transformation and transient expression modules.
• Introduced human sialylation pathway genes into glycosylation-deficient plant mutants.
• Co-expressed human α2,8-polysialyltransferases for polySia synthesis.

Main Results:

• Generated transgenic plants capable of synthesizing sialylated glycoproteins in α2,6- or α2,3-linkages.
• Achieved synthesis of polysialic acid structures with a degree of polymerization exceeding 40.
• Demonstrated functional activity of plant-derived polySia in cell-based assays, including inhibition of microglia activation.

Conclusions:

• The engineered plant platform allows controlled production of defined sialic acid structures.
• This approach facilitates experimental investigation of sialylation and glycan engineering.
• Plant-derived polySia exhibit functional activity, highlighting their therapeutic potential.