Description of Research Expertise

The Structural Biology of Retroviral Integrases. Retroviral integrase (IN) catalyzes the incorporation of viral cDNA into the host genome. The design of effective pharmacological treatments remains of paramount importance to the treatment of HIV/AIDS, and detailed structural models of intact IN oligomers in their various states are essential to new structure-based drug design efforts. My work on the retroviral integrase (IN) has focused on the understanding of higher-order structure and oligomeric forms of the full-length integrase when bound to host factors and DNA, with the overall goal of determining the molecular details of the larger macromolecular assemblies that underlie the steps of retroviral integration and other stages of the viral life cycle.

My research has married X-ray crystallography and rigorous biophysical methods to approach these fundamental questions. These approaches have included the application of small angle X-ray and neutron scattering (SAXS/SANS), analytical ultracentrifugation, multi-angle light scattering, and molecular modeling. These studies have yielded understanding of the quaternary structure and stoichiometry of IN, IN-DNA, and IN-host factor assemblies.

Most recently these approaches have been brought to bear on an exciting new class of allosteric inhibitors (“ALLINIs”) that is able to inhibit IN via selective modulation of its oligomeric properties. Surprisingly, ALLINIs interfere not with DNA integration but with viral particle assembly late during HIV replication. In 2016, we reported a breakthrough in the structural biology of HIV Integrase: the first crystal structure of HIV-1 Integrase in complex with the ALLINI GSK 1264. To our knowledge, this is the first time full-length HIV-1 integrase has been crystallized. The structure shows GSK1264 bound to the dimer interface of the catalytic domain, and also positioned at this interface is a C-terminal domain (CTD) from an adjacent IN dimer. In the crystal lattice, IN forms an open polymer mediated by this interaction. Further studies of a panel of ALLINIs show that HIV escape mutants with reduced sensitivity commonly alter amino acids at or near the inhibitor-mediated interface, and that HIV escape mutations often encode substitutions that reduce multimerization.