Lens-epithelium-derived-growth factor (LEDGF/p75) is an essential host protein for integration of HIV-1 DNA into host genome. Earlier alanine scanning mutational analysis has revealed that residues 1365, D366 and F406 in the integrase binding domain (IBD) of p75 are critical for interaction with HIV-1 integrase (IN), while K364, V408 have intermediate effect and residues N367, L368, R405, K407 show wild type binding with IN. To gain insight into contribution of side chains of 1368 and V408 that are adjacent to critical residues 1365 and F406, respectively, site directed mutation of these residues to Ile/Leu, Met and Phe has been performed and characterized in this study. In contrast to alanine substitution, L368F mutation showed a similar to 25% decrease, while V408L and V408F showed wild type binding, to IN. Docking analysis of 1365, D366 and F406 mutants of IBD with IN predicts that interaction between residue M178(IN) and 1365(1BD) might lead to an encounter complex formation. Accordingly, M178I mutant of IN failed to interact with IBD. Interestingly, a L368F/V408F double mutant of IBD restored binding to M178I mutant of IN, indicating that altered hydrophobicity in the inter helical loops of IBD might make 1365 more accessible for interaction with IN. (C) 2017 Elsevier Inc. All rights reserved.