Recombinant Aspergillus niger Nascent polypeptide-associated complex subunit alpha (egd2)
Description
2.1. Biological Role
The NAC complex, composed of alpha and beta subunits, interacts with nascent polypeptide chains emerging from ribosomes. Its primary function is to prevent premature interactions with other cellular components, ensuring proper protein folding and targeting . BetaNAC binds directly to the ribosome, while both subunits contact nascent chains .
3.1. Gene Source and Expression
The eg2 gene from Trichoderma reesei encodes an endoglucanase (EC 3.2.1.4) capable of hydrolyzing cellulose. Recombinant A. niger strains (e.g., D15[eg2]PyrG) expressing eg2 under the constitutive gpd promoter were evaluated for enzyme production .
3.3. Fermentation Optimization
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Maximum activity (54 U/mL) was achieved in 10% whey medium with 0.6% NaNO₃ .
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Glycosylation variability led to heterogeneity in SDS-PAGE profiles (45–65 kDa) .
4.1. Promoter Selection
The gpd promoter (glyceraldehyde-3-phosphate dehydrogenase) was used for constitutive expression of eg2 . This contrasts with inducible promoters (e.g., glaA), which require specific carbon sources .
4.2. Host Strain Selection
The protease-deficient A. niger D15 strain minimizes degradation of recombinant proteins during secretion .
4.3. Secretion Pathway Optimization
Fungal secretion pathways involve ER-associated chaperones (e.g., BipA, Hsp70) and glycosylation machinery . Overexpression of foldases (e.g., Pdi) and stress-responsive genes (e.g., RESS) was observed in recombinant strains .
Product Specs
Target Background
KEGG: ang:ANI_1_290134
STRING: 5061.CADANGAP00011626
