Nucleic Acids Research, 2002, Vol. 30, No. 20 4452-4459
© 2002 Oxford University Press
The role of the phosphorus BIBII transition in proteinDNA recognition: the NF-
B complex
Unité de RMN des Biomolécules, URA 2185 CNRS and 1 Unité de Virologie et dImmunologie Cellulaire, URA 1930 CNRS, Institut Pasteur, 28 rue du Docteur Roux, 75015 Paris, France
*To whom correspondence should be addressed. Tel: +33 1 45 68 88 71; Fax: +33 1 45 68 89 29; Email: murield{at}pasteur.fr
We examined, by 1H and 31P NMR, the solution structure of a 16 bp non-palindromic DNA fragment (16M2) containing the HIV-1 NF-
B-binding site, in which the sequences flanking the
B site had been mutated. 31P NMR was particularly useful for obtaining structural information on the phosphodiester backbone conformation. Structural features were then compared with those of the two previously studied DNA fragments corresponding, respectively, to the native
B fragment (16N) and a fragment in which mutations have been introduced at the 5' end of the
B site (16M1). For the mutated 16M2 duplex, NMR data showed that the BIBII equilibrium, previously reported for the native fragment (16N) at the
B flanking steps, was lost. The role of the BIBII equilibrium in NF-
B recognition by DNA was then investigated by electrophoretic mobility shift assay. We found that the isolated
B site has the potential to bind efficiently due to the BIBII equilibrium of the
B flanking sequences.