http://www.rcsb.org/pdb/education_discussion/molecule_of_the_month/download/Enhanceosome.pdf

Exploring the StructureThis model of the entire interferon-b enhancer was created by Daniel Panne based on several crystallographic structures (PDB entries 1t2k, 2pi0, 2o6g and 2o61); click here for coordinates of the model). It reveals several surprising aspects of the assembly. First, it shows that the DNA is nearly straight--some researchers had predicted that the DNA would be significantly bent. Second, the interaction between the proteins is very limited, even though the binding of the proteins is known to be cooperative, such that binding of one protein promotes the binding of others. This may be a consequence of several things. Several of the proteins bind on opposite sides of the same part of the DNA, so the proteins may promote binding by distorting the DNA slightly into a preferred conformation. Also, the crystal structures of ATF-2/c-Jun and the IRF proteins were solved using only the DNA-binding portions of the proteins, so the missing portions of the proteins may interact cooperatively with their neighbors. Finally, inside cells, CREB-binding protein or p300 (shown on the previous page) might generate a strong cooperative effect through its binding to the different proteins. Click on the image to view an interactive Jmol version.

Additional Information on EnhanceosomesD. Panne, T. Maniatis and S. C. Harrison (2007) An atomic model of the interferon-b enhanceosome. Cell 129, 1111-1123.D. Panne (2008) The enhanceosome. Current Opinion in Structural Biology 18, 236-242.L. Wang, Y. Tang, P. A. Cole and R. Marmorstein (2008) Structure and chemistry of the p300/CBP and Rtt109 histone acetyltransferases: implications for histone acetyltransferase evolution and function. Current Opinion in Structural Biology 18, 741-747.Number of genes in the human genome: International Humane Genome Sequencing Consortium (2004) Finishing the euchromatic sequence of the human genome. Nature 431, 931-945.Number of transcription factors in the human genome: M. M. Babu, N. M. Luscombe, L. Aravind, M. Gerstein and S. A. Teichmann (2004) Structure and evolution of transcriptional regulatory networks. Current Opinion in Structural Biology 14, 283-291.