A crystal structure of the integrase binding domain (IBD) of the lens epithelium-derived growth factor (LEDGF/p75) in complex with the dimer of the HIV-1 integrase (IN) catalytic core domain (CCD) provides useful information that might help in the understanding of essential protein-protein contacts in HIV-1. However, mutagenic studies indicated that interactions between the full-length proteins were more extensive than the contacts observed in the co-crystal structure of the isolated domains. On the other hand, the biochemical characterization of the interaction between full-length IN and LEDGF/p75 has recently proved that LEDGF/p75 promotes IN tetramerization with two LEDGF/p75 IBD molecules bound to the IN tetramer. This experimental evidence suggests that to obtain a complete structural description of the interactions between the two proteins, the full-length tetrameric structure of IN should be considered. Our aim was to obtain a detailed picture of HIV-1 IN interactions with cellular co-factors that was of general interest, particularly for the development of small molecule IN inhibitors, which mimic the IBD of LEDGF/p75. To this end, we performed bioinformatics analyses to identify protein sequence domains involved in long-range recognition. Subsequently, we applied molecular dynamics techniques to investigate the detailed interactions between the complete tetrameric form of IN and two molecules of the IBD of LEDGF/p75. Our dynamic picture is in agreement with experimental data and, thereby, provides new details of the IN-LEDGF/p75 interaction.
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