A SOLUBLE ACTIVE MUTANT OF HIV-1 INTEGRASE - INVOLVEMENT OF BOTH THE CORE AND CARBOXYL-TERMINAL DOMAINS IN MULTIMERIZATION

Structural studies of human immunodeficiency virus type 1 (HIV-1) inte grase have been impeded by the low solubility of the protein. By syste matic replacement of hydrophobic residues, we previously identified a single amino acid change (F185K) that dramatically improved the solubi lity of the catalytic domain of HIV-1 integrase and enabled the struct ure to be determined by x-ray crystallography. We have introduced the same mutation into full-length HIV-1 integrase. The resulting recombin ant protein is soluble and fully active in vitro, whereas, HIV-1 carry ing the mutation is replication-defective due to improper virus assemb ly. Analysis of the recombinant protein by gel filtration and sediment ation equilibrium demonstrate a dimer-tetramer self-association. We fi nd that the regions involved in multimerization map to both the cataly tic core and carboxyl-terminal domains. The dramatically improved solu bility of this protein make it a good candidate for structural studies .