Abstact

We report the solution structure of the chemotactic cytokine (chemokine) vMIP-II. This protein has unique biological activities in that it blocks infection by several different human immunodeficiency virus type 1 (HIV-1) strains. This occurs because vMIP-II binds to a wide range of chemokine receptors, some of which are used by HJV to gain cell entry. vMIP-II is a monomeric protein, unlike most members of the chemokine family, and its structure consists of a disordered N-terminus, followed by a helical turn (Gln25-Leu27), which leads into the first strand of a three-stranded antiparallel beta-sheet (Ser29-Thr34; Gly42-Thr47; Gln52-Asp56). Following the sheet is a C-terminal alpha-helix, which extends from residue Asp60 until Gln68. The final five residues beyond the C-terminal helix (Pro70-Arg74) are in an extended conformation, but several of these C-terminal residues contact the first beta-strand. The structure of vMIP-II is compared to other chemokines that also block infection by HIV-1, and the structural basis of its lack of ability to form a dimer is discussed.