Expression and in vitro glycosylation of recombinant edible bird nest (EBN) mucin

Edible bird's nest (EBN) is considered a delicacy in Chinese cuisine. The nests are produced by male swiftlets (Aerodramus sp.). Due to their high price, the nutritional benefit from EBN can currently only be afforded by affluent consumers. Therefore, the ability to identify and produce recombinant, functional EBN mucins is highly desirable. Herein, we report the identification, bacterial expression, purification and glycosylation of the first recombinant mucin derived from the Edible-nest Swiftlet Aerodramus fuciphagus (AfMuc). Recombinant AfMuc was successfully expressed at high expression levels and purified to near homogeneity by nickel-chelation affinity chromatography. The in vitro glycosylation of the recombinant AfMuc protein backbone resulted in the addition of up to four GalNAc residues and could be achieved by using a human and a previously unstudied Aerodramus fuciphagus polypeptide N-acetylgalactosaminyltransferase (HsGalNT2 and AfGalNT2, respectively). A comparison of the biochemical properties of these enzymes revealed characteristics of these enzymes.