Nucleic Acids Research, Vol 25, Issue 19 3808-3815, Copyright © 1997 by Oxford University Press
MR Conte, AN Lane and G Bloomberg
The effect of leucine zipper proteins binding to the DNA recognition site
is controversial. Results from crystallography, gel and solution methods
have led to opposite conclusions about the conformation of the DNA in the
complex. The role of the DNA binding site in the recognition process and in
the gene induction mediated by transcription factors needs to be
investigated further. In this article the self- complementary 16 bp
oligodeoxynucleotide (CATGTGACGTCACATG)2, which contains the cAMP response
element recognised by numerous transcription factors of the leucine zipper
family, has been examined free from proteins and in its interaction with
the mammalian activating transcription factor 2. The recognition process
has been investigated by circular dichroism analysis, which has revealed
conformational changes in both DNA and protein upon binding. The solution
structure of the 16mer, important in order to define the effects induced by
binding of leucine zipper proteins and the intrisic bending properties of
DNA, has been determined from NMR data using direct refinement against NOE
intensities, analysis of scalar coupling constants and restrained molecular
dynamics calculations. Final structures starting from the A and B forms of
DNA agreed to a pairwise root mean square deviation (r.m.s.d.) of 1.04 +/-
0.3 A (0.7 +/- 0.2 A to the average) for all atoms. The terminal base pairs
were less well determined, and the pairwise deviation of the 12 core bp was
0.83 +/- 0.27 A (0.55 +/- 0.19 A to the average). The final structures are
within the B-family with an average helical twist of 36+/-2 degrees. No
significant intrinsic DNA bend is shown in the activating transcription
factor regulatory site. However, there are substantial deviations from the
canonical B-DNA (r.m.s.d. = 3.6 A) in the core of the molecule, associated
with relatively large base inclinations.
ARTICLES
Solution structure of the ATF-2 recognition site and its interaction with the ATF-2 peptide
Division of Molecular Structure, National Institute for Medical Research, The Ridgeway, Mill Hill, London NW7 1AA, UK. s.conte@ic.ac.uk
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