Related Experiment Video
Updated: Jul 9, 2026
08:26
Analysis of N-glycans from Raphanus sativus Cultivars Using PNGase H+
Published on: June 25, 2018
N-glycan modification in Aspergillus species
Elke Kainz1, Andreas Gallmetzer, Christian Hatzl
1Fungal Genomics Unit, Austrian Research Centers and BOKU Vienna, Muthgasse 18, A-1190 Vienna, Austria.
Applied and Environmental Microbiology
|December 18, 2007
Summary
Filamentous fungi can now be engineered for therapeutic glycoprotein production. Researchers modified N-glycosylation pathways in Aspergillus species to create human-like glycan structures.
Area of Science:
- Biotechnology
- Molecular Biology
- Glycobiology
Background:
- Production of therapeutic glycoproteins in filamentous fungi is limited by differences in N-glycosylation pathways between fungi and mammals.
- Fungal cells cannot naturally produce complex N-glycans found on mammalian therapeutic proteins.
Purpose of the Study:
- To engineer protein N-glycosylation in Aspergillus species for the production of therapeutic glycoproteins.
- To develop fungal strains capable of producing humanized complex N-glycans on therapeutic proteins.
Main Methods:
- Functionally expressed heterologous chimeric fusion proteins in fungal hosts.
- Engineered N-glycan biosynthesis by introducing functional alpha-1,2-mannosidase and GlcNAc transferase I.
- Deleted algC genes involved in early fungal glycosylation pathway steps.
Main Results:
- Isolated a strain producing increased amounts of Man5GlcNAc2 type N-glycans.
- Achieved GlcNAcMan5GlcNac2 N-glycans through further engineering.
- Produced Man3GlcNAc2 N-glycans by deleting algC genes.
Conclusions:
- Demonstrated successful modification of fungal N-glycosylation pathways in Aspergillus.
- This glycan engineering is a significant step towards producing humanized complex N-glycans on therapeutic proteins in filamentous fungi.
Related Concept Videos
01:25Protein Glycosylation
Glycosylation, the most common post-translational modification for proteins, serves diverse functions. Adding sugars to proteins makes the proteins more resistant to proteolytic digestion. Glycosylated proteins can act as markers and receptors to promote cell-cell adhesion. Additionally, they have many essential quality control functions in the cell, such as correct protein folding and facilitating transport of misfolded proteins to the cytosol, which can be degraded.
Glycosylation occurs in...
Glycosylation occurs in...
01:24Oligosaccharide Assembly
Protein glycosylation starts in the ER lumen and continues in the Golgi apparatus. Glycosyltransferases catalyze the addition of sugar molecules or glycosylation of proteins. Usually, these enzymes add sugars to the hydroxyl groups of selected serine or threonine residues to form O-linked glycans or the amino groups of asparagine residues to form N-linked glycans. Different positions on the same polypeptide chain can contain differently linked glycans.
Multiple sugar molecules that may or may...
Multiple sugar molecules that may or may...
01:05Proteoglycans
Glycans, a class of complex heterogeneous molecules, can be covalently attached to proteins to form glycosylated proteins that regulate various physiological and pathological processes. Glycosylated proteins or glycoproteins comprise N-linked and O-linked oligosaccharides. O-glycosylation is the most common type of protein glycosylation. Here, glycans attach to the oxygen atom of the hydroxyl groups of Serine or Threonine residues. O-linked glycosylation occurs later in protein processing,...
01:26Protein Modifications in the RER
Modification of secretory and transmembrane proteins entering the rough ER begins in the ER lumen. These modifications aid in protein folding and stabilize the acquired tertiary structure. Protein modifications in the rough ER co-occur at different stages of protein folding.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.
Broadly, these modifications can be categorized into four main categories — glycosylation, formation of disulfide bonds, assembly of protein subunits, and specific proteolytic cleavages like removal of signal sequences.
01:28Fungal Phylum Ascomycota
Phylum Ascomycota, a major division within the subkingdom Dikarya, comprises a diverse range of fungal species, including both unicellular yeasts and filamentous molds such as Aspergillus and Penicillium. These fungi thrive in a variety of habitats, from aquatic ecosystems to terrestrial environments, playing crucial ecological and economic roles.Morphology and ReproductionThe defining characteristic of Ascomycetes, commonly referred to as sac fungi, is the ascus—a sac-like structure that...
01:29Protein Folding Quality Check in the RER
ER is the primary site for the maturation and folding of soluble and transmembrane secretory proteins. The calnexin cycle is a specific chaperone system that folds and assesses the confirmation of N-glycosylated proteins before they can exit the ER lumen. The primary players of this quality check pipeline are the lectins, ER-resident chaperones, and a glucosyl transferase enzyme. In case the calnexin system in the lumen fails to salvage a misfolded protein, it is transported to the cytoplasm...