A functional NF-κB binding site in the human papillomavirus type 16 long control region

By computer search, we identified one potential NF-kappa B binding site in the HPV16 long control region (LCR) at position 7554-7563 having two mismatches in comparison to the consensus NF-kappa B binding site of the Ig kappa L promoter. Bandshift experiments with nuclear extracts from HeLa cells or purified glutathione S-transferase-p65 fusion protein clearly demonstrated that NF-kappa B is able to bind to this region of the LCR. However, in comparison to NF-kappa B binding on a consensus probe, the affinity of NF-kappa B for this site is about 250-fold reduced. When mutations were introduced into this NF-kappa B binding site, the activity of the LCR was increased, strongly suggesting that NF-kappa B was acting as a transcriptional repressor in the context of the HPV16 LCR. In addition, overexpression of NF-kappa B p65 repressed the activity of the HPV16 LCR, strengthening this conclusion. (C) 2000 Academic Press.