Lack of endoplasmic reticulum 1,2-α-mannosidase activity that trims N-glycan Man9GlcNAc2 to Man8GlcNAc2 isomer B in a manE gene disruptant of Aspergillus oryzae.

The gene manE, encoding a probable class I endoplasmic reticulum 1,2-α-mannosidases (ER-Man), was identified from the filamentous fungus Aspergillus oryzae due to similarity to orthologs. It removes a single mannose residue from Man(9)GlcNAc(2), generating Man(8)GlcNAc(2) isomer B. Disruption of manE caused drastic decreases in ER-Man activity in A.

Cloning and expression of 1,2-alpha-mannosidase gene (fmanIB) from filamentous fungus Aspergillus oryzae: in vivo visualization of the FmanIBp-GFP fusion protein.

1,2-alpha-Mannosidase catalyzes the specific cleavage of 1,2-alpha-mannose residues from protein-linked N-glycan. In this study, a novel DNA sequence homologous to the authentic 1,2-alpha-mannosidase was cloned from a cDNA library prepared from solid-state cultured Aspergillus oryzae. The fmanIB cDNA consisted of 1530 nucleotides and encoded a protein of 510 amino acids in which all consensus motifs of the class I alpha-mannosidase were conserved.