CHARACTERIZATION OF TRUNCATED HUMAN MANNAN-BINDING PROTEIN (MBP) EXPRESSED IN ESCHERICHIA-COLI

Mannan-binding protein (MBP) is a calcium-dependent mammalian serum le ctin important in first-line host defense. MBP belongs to the collecti n family, which is characterized by an NH2-terminal cysteine-rich doma in, a collagen-like domain, a neck domain, and a carbohydrate recognit ion domain (CRD). We have expressed a recombinant human MBP, consistin g of the short collagen region (two repeats of Gly-Xaa-Yaa amino acid sequences), the neck domain, and the CRD, in Escherichia coli. The tru ncated MBP was capable of forming trimers by association of the neck d omain and could bind sugar with a specificity similar to that of the n ative form. Results of hemagglutination inhibition (HI) assay of influ enza A virus showed that the truncated MBP inhibited hemagglutination less strongly, although the native MBP induced the HI phenomenon. Thes e results suggest that an oligomeric structure is an advantage for MBP to have full biological activity against influenza A virus.