TY - JOUR
T1 - Glycoengineering of Aspergillus nidulans to produce precursors for humanized N-glycan structures
AU - Anyaogu, Diana Chinyere
AU - Hansen, Anders Holmgaard
AU - Hoof, Jakob Blæsbjerg
AU - Majewska, Natalia I.
AU - Contesini, Fabiano Jares
AU - Paul, Jackson T.
AU - Nielsen, Kristian Fog
AU - Hobley, Timothy John
AU - Yang, Shuang
AU - Zhang, Hui
AU - Betenbaugh, Michael
AU - Mortensen, Uffe Hasbro
N1 - Publisher Copyright:
© 2021
PY - 2021/9
Y1 - 2021/9
N2 - Filamentous fungi secrete protein with a very high efficiency, and this potential can be exploited advantageously to produce therapeutic proteins at low costs. A significant barrier to this goal is posed by the fact that fungal N-glycosylation varies substantially from that of humans. Inappropriate N-glycosylation of therapeutics results in reduced product quality, including poor efficacy, decreased serum half-life, and undesirable immune reactions. One solution to this problem is to reprogram the glycosylation pathway of filamentous fungi to decorate proteins with glycans that match, or can be remodeled into, those that are accepted by humans. In yeast, deletion of ALG3 leads to the accumulation of Man5GlcNAc2 glycan structures that can act as a precursor for remodeling. However, in Aspergilli, deletion of the ALG3 homolog algC leads to an N-glycan pool where the majority of the structures contain more hexose residues than the Man3-5GlcNAc2 species that can serve as substrates for humanized glycan structures. Hence, additional strain optimization is required. In this report, we have used gene deletions in combination with enzymatic and chemical glycan treatments to investigate N-glycosylation in the model fungus Aspergillus nidulans. In vitro analyses showed that only some of the N-glycan structures produced by a mutant A. nidulans strain, which is devoid of any of the known ER mannose transferases, can be trimmed into desirable Man3GlcNAc2 glycan structures, as substantial amounts of glycan structures appear to be capped by glucose residues. In agreement with this view, deletion of the ALG6 homolog algF, which encodes the putative α-1,3- glucosyltransferase that adds the first glucose residue to the growing ER glycan structure, dramatically reduces the amounts of Hex6-7HexNAc2 structures. Similarly, these structures are also sensitive to overexpression of the genes encoding the heterodimeric α-glucosidase II complex. Without the glucose caps, a new set of large N-glycan structures was formed. Formation of this set is mostly, perhaps entirely, due to mannosylation, as overexpression of the gene encoding mannosidase activity led to their elimination. Based on our new insights into the N-glycan processing in A. nidulans, an A. nidulans mutant strain was constructed in which more than 70% of the glycoforms appear to be Man3-5GlcNAc2 species, which may serve as precursors for further engineering in order to create more complex human-like N-glycan structures.
AB - Filamentous fungi secrete protein with a very high efficiency, and this potential can be exploited advantageously to produce therapeutic proteins at low costs. A significant barrier to this goal is posed by the fact that fungal N-glycosylation varies substantially from that of humans. Inappropriate N-glycosylation of therapeutics results in reduced product quality, including poor efficacy, decreased serum half-life, and undesirable immune reactions. One solution to this problem is to reprogram the glycosylation pathway of filamentous fungi to decorate proteins with glycans that match, or can be remodeled into, those that are accepted by humans. In yeast, deletion of ALG3 leads to the accumulation of Man5GlcNAc2 glycan structures that can act as a precursor for remodeling. However, in Aspergilli, deletion of the ALG3 homolog algC leads to an N-glycan pool where the majority of the structures contain more hexose residues than the Man3-5GlcNAc2 species that can serve as substrates for humanized glycan structures. Hence, additional strain optimization is required. In this report, we have used gene deletions in combination with enzymatic and chemical glycan treatments to investigate N-glycosylation in the model fungus Aspergillus nidulans. In vitro analyses showed that only some of the N-glycan structures produced by a mutant A. nidulans strain, which is devoid of any of the known ER mannose transferases, can be trimmed into desirable Man3GlcNAc2 glycan structures, as substantial amounts of glycan structures appear to be capped by glucose residues. In agreement with this view, deletion of the ALG6 homolog algF, which encodes the putative α-1,3- glucosyltransferase that adds the first glucose residue to the growing ER glycan structure, dramatically reduces the amounts of Hex6-7HexNAc2 structures. Similarly, these structures are also sensitive to overexpression of the genes encoding the heterodimeric α-glucosidase II complex. Without the glucose caps, a new set of large N-glycan structures was formed. Formation of this set is mostly, perhaps entirely, due to mannosylation, as overexpression of the gene encoding mannosidase activity led to their elimination. Based on our new insights into the N-glycan processing in A. nidulans, an A. nidulans mutant strain was constructed in which more than 70% of the glycoforms appear to be Man3-5GlcNAc2 species, which may serve as precursors for further engineering in order to create more complex human-like N-glycan structures.
KW - Aspergillus nidulans
KW - Filamentous fungi
KW - Glycoengineering
KW - ManGlcNAc
KW - N-Glycosylation
UR - http://www.scopus.com/inward/record.url?scp=85108875212&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=85108875212&partnerID=8YFLogxK
U2 - 10.1016/j.ymben.2021.06.001
DO - 10.1016/j.ymben.2021.06.001
M3 - Article
C2 - 34174425
AN - SCOPUS:85108875212
SN - 1096-7176
VL - 67
SP - 153
EP - 163
JO - Metabolic Engineering
JF - Metabolic Engineering
ER -