THE SOLUTION STRUCTURE OF HIV-1 NEF REVEALS AN UNEXPECTED FOLD AND PERMITS DELINEATION OF THE BINDING SURFACE FOR THE SH3 DOMAIN OF HCK TYROSINE PROTEIN-KINASE

The solution structure of HIV-1 Nef has been solved by multidimensiona l heteronuclear NMR spectroscopy. The construct employed to circumvent problems associated with aggregation was a double-deletion mutant (De lta 2-39, Delta 159-173) in which conformationally disordered regions of the protein at the N terminus and in a long solvent-exposed flexibl e loop were removed, without affecting the properties or structural in tegrity of the remainder of the protein. Despite the absence of any se quence similarity, the overall fold of Nef is reminiscent of that of t he family of winged helix-turn-helix DNA binding proteins. The binding surface of Nef for the SH3 domain of Hck tyrosine protein kinase has been mapped and reveals a non-contiguous (in terms of amino-acid seque nce) interaction surface. This unique feature may suggest possible ave nues for drug design aimed at inhibiting the interaction between Nef a nd SH3 domains.