Fos and Jun do not bend the AP-1 recognition site.
We have used a solution-based DNA cyclization assay and a gel-phasing method to show that contrary to previous reports [Kerppola, T. K. & Curran, T. (1991) Cell 66, 317-326], basic region leucine zipper proteins Fos and Jun do not significantly bend their AP-1 recognition site. We have constructed two sets of DNA constructs that contain the 7-bp 5'-TGACTCA-3' AP-1 binding site, from either the yeast or the human collagenase gene, which is well separated from and phased by 3-4 helical turns against an A tract-directed bend. The cyclization probabilities of DNAs with altered phasings are not significantly affected by Fos-Jun binding. Similarly, Fos-Jun and Jun-Jun bound to differently phased DNA constructs show insignificant variations in gel mobilities. Both these methods independently indicate that Fos and Jun bend their AP-1 target site by <5 degrees, an observation that has important implications in understanding their mechanism of transcriptional regulation.
Sitlani
A
A
Department of Chemistry, Yale University, New Haven, CT 06511, USA.
Crothers
D M
DM
D001483:Base Sequence; D001665:Binding Sites; D017364:Collagenases / Q000235:genetics; D004274:DNA, Recombinant / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D006801:Humans; D066298:In Vitro Techniques; D007700:Kinetics; D016350:Leucine Zippers; D008969:Molecular Sequence Data; D009690:Nucleic Acid Conformation; D011485:Protein Binding; D016760:Proto-Oncogene Proteins c-fos / Q000378:metabolism*; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism*; D012441:Saccharomyces cerevisiae / Q000235:genetics / Q000378:metabolism; D018808:Transcription Factor AP-1 / Q000235:genetics / Q000378:metabolism*
D004274:DNA, Recombinant; D016760:Proto-Oncogene Proteins c-fos; D016755:Proto-Oncogene Proteins c-jun; D018808:Transcription Factor AP-1; D017364:Collagenases