REVERSAL OF INTRINSIC DNA BENDS IN THE IFN-BETA GENE ENHANCER BY TRANSCRIPTION FACTORS AND THE ARCHITECTURAL PROTEIN HMG I(Y)

In this paper, we investigate DNA bending induced by proteins required for virus induction of the human interferon-beta (IFN beta) gene. We show that NF-kappa B-DNA complexes that are functionally distinct in t he context of the IFN beta enhancer are also conformationally distinct and that two sites in the enhancer contain in-phase bends that are co unteracted or reversed by the binding of NF-kappa B, ATF-2/c-Jun, and HMG I(Y). Strikingly, this modulation of intrinsic enhancer architectu re results in an orientation that favors predicted protein-protein int eractions in a functional nucleoprotein complex, the enhanceosome. Fur thermore, the subtle modulation of DNA structure by HMG I(Y) in this p rocess distinguishes it from other architectural factors.