Crystal structure of macrophage migration inhibitory factor from human Å lymphocyte at 2.1 Å resolution

Abstract

The three‐dimensional structure of the macrophage migration inhibitory factor (MIF) from human lymphocytes has been determined by X‐ray crystallography at 2.1 A resolution. The structure was solved by a molecular replacement technique using the coordinates of rat MIF. The molecule forms a trimer structure similar to the rat MIF. However, unlike the rat MIF whose C‐terminal tail (residues 104–114) is disordered in the crystal, human MIF has a dermite main‐chain conformation up to the C‐terminal end. These eleven residues create two more β‐strands and join to the inter‐subunit β‐sheet which contribute to forming a trimer structure. Thus, the trimer structure consists of three seven‐stranded β‐sheets surrounded by six α‐helices. Each β‐sheet is comprised of β‐strands from each of the three monomers. This architecture is almost identical to 5‐carboxymethyl‐2‐hydroxymuconate isomerase (CHMI) and is related to the E. coli signal transducing protein P_II.