Purification and characterization of an adhesin from Pasteurella haemolytica

We purified an adhesin from Pasteurella. haemolytica by affinity chromatogr aphy using glutaraldehyde treated rabbit erythrocytes stroma, The adhesin i s a protein of 68 kDa, as determined by SDS-PAGE, and the most abundant ami no acids constituting this protein mere Gly, Ser, Glx, and Ala, and low con centrations of Cys, Met, and Tyr residues mere also found. The N-terminal s equence of the adhesin is ANEVNVYIYKQPYLI, No carbohydrate residues were de tected, The adhesin agglutinated rabbit erythrocytes but when the latter we re desialylated or pronase treated the agglutinating activity was abolished . The agglutinating activity of the adhesin was inhibited with N-acetyl-D-g lucosamine (GlcNAc), and in a lesser degree with N-acetyl-neuraminic acid ( NeuAc). GalNAc, N-glycolyl-neuraminic acid, N-deacetylated GlcNAc, or neutr al sugars do not modify the activity of the adhesin, The equatorial -OH on C4 and the NH-acetylated group on C2 from GlcNAc, as well as the 4-OH and N H-acetylated group on C5 from NeuAc seem to be responsible for the interact ion with the adhesin, The protein is divalent cation-dependent and thermola bile, As for the agglutinating activity, the adhesion of P.haemolytica to t racheal cell-cultures was inhibited by GlcNAc, NeuAc or the purified adhesi n, strongly suggesting that the P.haemolytica adhesin plays an important ro le in infection,