Purification of the receptor for the N-acetyl-d-glucosamine specific adhesin of Mannheimia haemolytica from bovine neutrophils

The GlcNAc-specific adhesin from Mannheimia haemolytica (MhA) has been shown to participate in pathogenicity of mannheimiosis due to its capacity to adhere to tracheal epithelial cells and activate the oxidative burst of bovine neutrophils. In this work, we purified the MhA receptor from bovine neutrophils (MhAr) by affinity chromatography on MhA-Sepharose. The MhAr, which corresponded to approximately 2% of the protein from cell lysate, is a glycoprotein mainly composed of Glu, Ala, Ser, Gly, and Asp, without cysteine. The glycan portion, which corresponds to 20% by weight, is composed of GalNAc, GlcNAc, Man, Gal, and NeuAc. The receptor is a 165-kDa glycoprotein, as determined by molecular sieve chromatography under native conditions; SDS-PAGE analysis shows a heterodimer of 83 and 80 kDa subunits. This work suggests that the GlcNAc-containing receptor plays a relevant role by activating bovine neutrophils through non-opsonic mechanisms.