Biomedical Engineering Reference
In-Depth Information
C
HAPTER
14
Engineering Fungal Expression
Systems: Recombinant Expression
of Two Class I
α
-1,
2-Mannosidases from the
Filamentous Fungus
Aspergillus nidulans
C. Joshua Eades and William E. Hintz*
Abstract
Engineering of glycan specifi c expression systems is being undertaken in numerous
different expression systems, including fungal expression systems. N-glycosyl-
ation, the post-translational attachment of specifi c oligosaccharides to asparagine
residues in newly formed proteins, has been shown to be important in modulating
the biochemical and/or pharmacological properties of proteins and may affect
half-life, immunogenicity, activity, and/or effi cacy of glycoproteins. The fi delity
of expressed proteins may thus be maintained by engineering expression systems
to produce native N-glycans. The α-1,2-mannosidases are key in the development
of N-glycans in both higher and lower eukaryotes. Understanding their biochem-
istry and substrate specifi city has important applications in the development of
humanized protein expression systems. Here we report an analysis and biochemi-
cal characterization of α-1,2-mannosidase enzymes from the fi lamentous fungus
Aspergillus nidulans
. Two Class 1 α-1,2-mannosidases from
A. nidulans
are shown
to be capable of reducing the oligosaccharide Man
9
GlcNAc
2
to Man
5
GlcNAc
2
,
the precursor for further complex N-glycan structures—this indicates that these
enzymes may have overlapping and possibly redundant activities. The α-1,2-
