MAPPIT (MAmmalian Protein–Protein Interaction Trap) as a tool to study HIV reverse transcriptase dimerization in intact human cells

The high mutation rate of Human Immunodeficiency Virus (HIV) leads to the rapid derivation of compound-resistant virus strains and thus necessitates the identification and development of compounds with alternative mode of actions. MAPPIT (MAmmalian Protein–Protein Interaction Trap) is a highly efficient tool to study protein–protein interactions in intact human cells and is applied to study the dimerization process of the HIV reverse transcriptase complex. Highly specific signals for the p66/p51 and p66/p66 interactions could readily be detected. Specificity was established further by introducing mutations in either subunit. Treatment with efavirenz resulted in an increased MAPPIT signal, with an EC50 value of 64 nM for the p66/p51 interaction, and allowed detection of the p51/p51 homodimerization, confirming the context-dependent asymmetric contribution of both subunits. These results show that MAPPIT can be used as a novel screening tool for anti-HIV compounds in intact human cells.