Our long-term goals are to understand how proteins interact with each other and how these interactions underlie biological processes. We are particularly interested in molecular and structural switches that control how proteins form high-order quaternary interactions, or macromolecular assemblies. In one set of projects, we are studying the transformation between the immature and mature forms of orthoretroviruses, with emphasis on the Human Immunodeficiency Virus (collaboration with Barbie Ganser-Pornillos and Mark Yeager, Department of Molecular Physiology and Biological Physics) and Rous Sarcoma Virus (collaboration with Volker Vogt, Cornell University). We are also applying the assembly principles that we learn from orthoretroviral capsids on the design of nanoparticles that could be used in imaging of cancer cells in situ and in targeted drug delivery (collaboration with Kim Kelly, Department of Biomolecular Engineering). In a second set of projects, we are studying protein complexes that mediate anti-viral responses as part of the cellular innate immune system. We use X-ray crystallography and electron cryomicroscopy to determine the structures of individual proteins, protein-protein complexes, and assemblies. To test mechanistic models that arise from these structures, we use biochemical approaches to reconstitute viral and cellular assembly pathways in vitro. List of Publications in Pubmed