Cooperative role of calnexin and TigA in Aspergillus oryzae glycoprotein folding

In this study, we found that a protein disulfide isomerase homolog TigA can bind with A. oryzae CNX (AoCNX), which was revealed to specifically recognize monoglucosylated glycans, similarly to CNX derived from other species, and accelerate the folding of G1M9GN2-ribonuclease (RNase) in vitro. For refolding experiments, a homogeneous monoglucosylated high-mannose-type glycoprotein G1M9GN2-RNase was chemoenzymatically synthesized from G1M9GN-oxazoline and GN-RNase. Denatured G1M9GN2-RNase was refolded with highest efficiency in the presence of both soluble form of AoCNX and TigA. TigA contains two thioredoxin domains with CGHC motif, mutation analysis of which revealed that the one in N-terminal regions is involved in binding to AoCNX, while the other in catalyzing protein refolding. The results suggested that in glycoprotein folding process of A. oryzae, TigA plays a similar role as ERp57 in mammalian cells, as a partner protein of AoCNX.
Source: Glycobiology - Category: Biology Authors: Tags: Glycan Recognition Source Type: research