NF-KAPPA-B-MEDIATED CHROMATIN RECONFIGURATION AND TRANSCRIPTIONAL ACTIVATION OF THE HIV-1 ENHANCER IN-VITRO

NF-kappa B is a potent inducible transcription factor that regulates m any genes in activated T cells. In this report we examined the ability of different subunits of NF-kappa B to enhance HIV-1 transcription in vitro with chromatin templates. We find that the p65 subunit of NF-ka ppa B is a strong transcriptional activator of nucleosome-assembled HI V-1 DNA, whereas p50 does not activate transcription, and that p65 act ivates transcription synergistically with Sp1 and distal HIV-1 enhance r-binding factors (LEF-1, Ets-1, and TFE-3). These effects were observ ed with chromatin, but not with nonchromatin templates. furthermore, b inding of either p50 or p65 with Sp1 induces rearrangement of the chro matin to a structure that resembles the one reported previously for in tegrated HIV-1 proviral DNA in vivo. These results suggest that p50 an d Sp1 contribute to the establishment of the nucleosomal arrangement o f the uninduced provirus in resting T cells, and that p65 activates tr anscription by recruitment of the RNA polymerase II transcriptional ma chinery to the chromatin-repressed basal promoter.