Basic Science Award

HIV relies heavily on remodeling host regulatory networks for its replication. One major target of this remodeling process is the cellular ubiquitin machinery, which modifies proteins by adding ubiquitin moieties to target them for degradation and to modulate their activities. HIV exploits the ubiquitination system as a means to interfere with crucial antiviral pathways and immune mechanisms. Therefore, targeting interactions between HIV proteins and the human ubiquitin machinery is a promising direction for developing new anti-HIV therapeutics. Several viral proteins have been shown to interact with ubiquitin ligases to regulate the activity of both viral and host proteins. However, in terms of the exact molecular composition of HIV-human ubiquitin ligase complexes, their substrates and the protein-protein interaction network context this interface remains to a large extent uncharacterized. Here, I propose a strategy combining quantitative mass spectrometry and network analysis approaches to characterize protein-protein interactions and ubiquitination events between HIV-1 proteins and host ubiquitin ligases in the context of HIV-1 infection. Ubiquitin ligase-substrate relationships revealed by this strategy will be validated using a ligase trapping approach and their influence on the virus propagation will be characterized by RNAi. This project will reveal new ubiquitin ligases and their substrates relevant for HIV-1 infection, will identify specific targets for therapeutic interventions, and provide new insights into the role of the human ubiquitin machinery in immune response.