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Cell. 1991 Jul 26;66(2):317-26.

Fos-Jun heterodimers and Jun homodimers bend DNA in opposite orientations: implications for transcription factor cooperativity.

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Department of Molecular Oncology and Virology, Roche Institute of Molecular Biology, Nutley, New Jersey 07110.


Association of Fos and Jun with the AP-1 site results in a conformational change in the basic amino acid regions that constitute the DNA-binding domain. We show that Fos and Jun induce a corresponding alteration in the conformation of the DNA helix. Circular permutation analysis indicated that both Fos-Jun heterodimers and Jun homodimers induce flexure at the AP-1 site. Phasing analysis demonstrated that Fos-Jun heterodimers and Jun homodimers induce DNA bends that are directed in opposite orientations. Fos-Jun heterodimers bend DNA toward the major groove, whereas Jun homodimers bend DNA toward the minor groove. Fos and Jun peptides encompassing the dimerization and DNA-binding domains bend DNA in the same orientations as the full-length proteins. However, additional regions of both proteins influence the magnitude of the DNA bend angle. Thus, despite the amino acid sequence similarity in the basic region Fos-Jun heterodimers and Jun homodimers form topologically distinct DNA-protein complexes.

[Indexed for MEDLINE]

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