A Critical Role of the C-terminal Segment for Allosteric Inhibitor Induced Aberrant Multimerization of HIV-1 Integrase [DNA and Chromosomes]

August 12th, 2014 by Shkriabai, N., Dharmarajan, V., Slaughter, A., Kessl, J. J., Larue, R. C., Feng, L., Fuchs, J. R., Griffin, P. R., Kvaratskhelia, M.

Allosteric HIV-1 integrase (IN) inhibitors (ALLINIs) are a promising class of antiretroviral agents for clinical development. While ALLINIs promote aberrant IN multimerization and inhibit IN interaction with its cellular cofactor LEDGF/p75 with comparable potencies in vitro, their primary mechanism of action in infected cells is through inducing aberrant multimerization of IN. Crystal structures have shown that ALLINIs bind at the IN catalytic core domain dimer interface and bridge two interacting subunits. However, how these interactions promote higher-order protein multimerization is not clear. Here we used mass spectrometry-based protein footprinting to monitor surface topology changes in full length wild type (WT) and the drug-resistant A128T mutant INs in the presence of ALLINI-2. These experiments have identified protein-protein interactions that extend beyond the direct inhibitor binding site and which lead to aberrant multimerization of WT but not A128T IN. Specifically, we demonstrate that C-terminal residues K264 and K266 play an important role in the inhibitor induced aberrant multimerization of the WT protein. Our findings provide structural clues for exploiting IN multimerization as a new, attractive therapeutic target and are expected to facilitate development of improved inhibitors.