N-glycan sialylation in a silkworm-baculovirus expression system

Area of Science:

• Biotechnology
• Glycobiology
• Recombinant Protein Production

Background:

• The silkworm-baculovirus system is a powerful tool for producing recombinant proteins, including glycoproteins.
• Native silkworm N-glycosylation produces pauci-mannose type glycans lacking sialic acid and galactose, which differ from mammalian structures.
• Sialic acid residues are crucial for various protein functions, necessitating their incorporation into recombinant glycoproteins.

Purpose of the Study:

• To engineer silkworms for the production of glycoproteins with mammalian-like N-glycan structures, specifically incorporating sialic acid and galactose.
• To establish controllable pathways for galactosylation and sialylation in the silkworm expression system.
• To investigate the impact of different sialyltransferases and glycosyltransferases on N-glycan complexity.

Main Methods:

• Co-expression of galactosyltransferase and sialyltransferase enzymes in the silkworm.
• Supplementation of the silkworm culture medium with sialylation-related substrates.
• Modification of sialylation patterns by altering the specific sialyltransferase expressed.
• Co-expression of N-acetylglucosaminyltransferase II to enhance glycan complexity.

Main Results:

• Successful production of sialylated N-glycans on recombinant proteins in silkworms.
• Control over α2,3/α2,6 sialylation linkage by selecting specific sialyltransferases.
• Demonstration of di-sialylated N-glycan structures through the co-expression of N-acetylglucosaminyltransferase II.
• Significant advancement in tailoring N-glycosylation profiles in a silkworm expression system.

Conclusions:

• The study successfully established pathways for galactosylation and sialylation in silkworms, enabling the production of complex N-glycans.
• This glycoengineering approach provides a novel method for producing therapeutic glycoproteins with desired mammalian-like glycosylation patterns.
• The findings offer critical insights into controlling and manipulating N-glycosylation in silkworm-based recombinant protein production systems.