Fig. 8

DDX5 RNA binding motif 1a and the Walker B motif are essential for interaction with HEXIM1. a HeLa cells were co-transfected with different Myc-tagged DDX5 expressors (DDX5 wild type, DDX5-T176R + E178V + L179A and DDX5-E249Q). Cell lysates were harvested 48 h post co-transfection for co-immunoprecipitation. A Myc specific antibody or isotype matched control antibody was used for pull-down. Samples were subjected to SDS-PAGE and western blotting by probing for HEXIM1. To further validate that the interaction of DDX5 with HEXIM1 is RNA dependent, samples from Myc-DDX5 wild type were treated with RNase enzyme. The western blot shown is a representative from three independent experiments. b Western blot from whole cell lysates transfected with the different Myc-DDX5 constructs to ascertain level of expression. HeLa cells were co-transfected with different Myc-tagged DDX5 expressors (DDX5 wild type, DDX5-T176R + E178V + L179A and DDX5-E249Q). Cell lysates were harvested 48 h post transfection for Western blot using a Myc specific antibody. Mock or untransfected cell lysates were used as control. c Graphical abstract showing the proposed mechanistic action of DDX5 in HIV-1 transcription processivity