title: DNA loops induced by cooperative binding of transcriptional activator proteins and preinitiation complexes.
abstract: DNA conformational changes are essential for the assembly of multiprotein complexes that contact several DNA sequence elements. An approach based on atomic force microscopy was chosen to visualize specific protein-DNA interactions occurring on eukaryotic class II nuclear gene promoters. Here we report that binding of the transcription regulatory protein Jun to linearized plasmid DNA containing the consensus AP-1 binding site upstream of a class II gene promoter leads to bending of the DNA template. This binding of Jun was found to be essential for the formation of preinitiation complexes (PICs). The cooperative binding of Jun and PIC led to looping of DNA at the protein binding sites. These loops were not seen in the absence of either PICs, Jun, or the AP-1 binding site, suggesting a direct interaction between DNA-bound Jun homodimers and proteins bound to the core promoter. This direct visualization of functional transcriptional complexes confirms the theoretical predictions for the mode of gene regulation by trans-activating proteins.
authors.affiliation: Department of Immunology, Scripps Research Institute, La Jolla, CA 92037, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Becker
authors.forename: A
authors.initials: A
authors.lastname: Nikroo
authors.forename: T
authors.initials: T
authors.lastname: Brabletz
authors.forename: R A
authors.initials: RA
authors.lastname: Reisfeld
mesh_terms: D001665:Binding Sites; D004247:DNA / Q000378:metabolism / Q000648:ultrastructure*; D006801:Humans; D046911:Macromolecular Substances; D018625:Microscopy, Atomic Force; D009690:Nucleic Acid Conformation; D010957:Plasmids; D011485:Protein Binding; D011487:Protein Conformation; D016755:Proto-Oncogene Proteins c-jun / Q000378:metabolism / Q000648:ultrastructure*; D014158:Transcription, Genetic
chemical_list: D046911:Macromolecular Substances; D016755:Proto-Oncogene Proteins c-jun; D004247:DNA