The C/EBP family of proteins distorts DNA upon binding but does not introduce a large directed bend.
The DNA-bending properties of several C/EBP family proteins, bound to two different sites, have been determined using circular permutation and phasing analyses. All the proteins examined by circular permutation analysis induced a significant distortion in the DNA (40-66 degrees), and this distortion was of the same magnitude at both C/EBP sites. However, phasing analysis revealed that the size of the directed bend induced in the DNA by C/EBP proteins was only 1-4 degrees. Both the magnitude and orientation of the directed bend were affected by the specific sequence of the DNA-binding site. All proteins induced a directed bend of similar magnitude and orientation (toward the minor groove) when bound to the C/EBP site derived from the IgH enhancer, but the induced bend was smaller when the protein was bound to the C/EBP site derived from the VH1 promoter. The study also included a heterodimer between Ig/EBP and ATF4. Similar to C/EBP protein homodimers, this heterodimer induces a small directed bend of 4 degrees oriented toward the minor groove when bound to the enhancer-derived C/EBP site.
Avitahl
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N
Department of Microbiology, Columbia University College of Physicians and Surgeons, New York, New York 10032.
Calame
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K
D001483:Base Sequence; D001665:Binding Sites; D022762:CCAAT-Enhancer-Binding Proteins; D017931:DNA Primers / Q000737:chemistry; D004268:DNA-Binding Proteins / Q000378:metabolism*; D004742:Enhancer Elements, Genetic; D066298:In Vitro Techniques; D016350:Leucine Zippers; D046911:Macromolecular Substances; D008969:Molecular Sequence Data; D009687:Nuclear Proteins / Q000378:metabolism*; D009690:Nucleic Acid Conformation; D011401:Promoter Regions, Genetic; D014157:Transcription Factors / Q000378:metabolism*
D022762:CCAAT-Enhancer-Binding Proteins; D017931:DNA Primers; D004268:DNA-Binding Proteins; D046911:Macromolecular Substances; D009687:Nuclear Proteins; D014157:Transcription Factors