The enhanceosome is a protein complex

Protein complex

A multiprotein complex is a group of two or more associated polypeptide chains. If the different polypeptide chains contain different protein domain, the resulting multiprotein complex can have multiple catalytic functions...

 that binds to the "enhancer" region of a gene

Gene

A gene is a molecular unit of heredity of a living organism. It is a name given to some stretches of DNA and RNA that code for a type of protein or for an RNA chain that has a function in the organism. Living beings depend on genes, as they specify all proteins and functional RNA chains...

, found upstream or downstream, of the promoter, or within a gene. It accelerates the gene's transcription

Transcription (genetics)

Transcription is the process of creating a complementary RNA copy of a sequence of DNA. Both RNA and DNA are nucleic acids, which use base pairs of nucleotides as a complementary language that can be converted back and forth from DNA to RNA by the action of the correct enzymes...

. The binding and assembly of the activating proteins, some of which may be transcription factor

Transcription factor

In molecular biology and genetics, a transcription factor is a protein that binds to specific DNA sequences, thereby controlling the flow of genetic information from DNA to mRNA...

s, is cooperative due to energetically favorable protein-protein interaction

Protein-protein interaction

Protein–protein interactions occur when two or more proteins bind together, often to carry out their biological function. Many of the most important molecular processes in the cell such as DNA replication are carried out by large molecular machines that are built from a large number of protein...

s formed in the complex.

The best known example of the enhanceosome acts on the human

Human

Humans are the only living species in the Homo genus...

 interferon-beta gene, which is upregulated in cells that are infected by virus

Virus

A virus is a small infectious agent that can replicate only inside the living cells of organisms. Viruses infect all types of organisms, from animals and plants to bacteria and archaea...

es. Three activator proteins - NF-κB, an interferon activator protein such as IRF-3, and the ATF

Activating transcription factor

In molecular biology, activating transcription factor, ATF, is a class of AP-1 transcription factor dimers.Genes include ATF1, ATF2, ATF3, ATF4, ATF5, ATF6, and ATF7....

-2/c-Jun complex - cooperatively bind to the upstream enhancer region upon viral infection. The interaction is mediated by a fourth protein HMG-I

High mobility group

High-Mobility Group or HMG is a group of chromosomal proteins that help withtranscription, replication, recombination, and DNA repair.-Families:The HMG proteins are subdivided into 3 superfamilies each containing a characteristic functional domain:...

, which assists in stabilizing the complex by promoting inter-protein interactions. The assembled enhanceosome recruits transcriptional machinery such as RNA polymerase

RNA polymerase

RNA polymerase is an enzyme that produces RNA. In cells, RNAP is needed for constructing RNA chains from DNA genes as templates, a process called transcription. RNA polymerase enzymes are essential to life and are found in all organisms and many viruses...

 to the promoter region to initiate gene expression

Gene expression

Gene expression is the process by which information from a gene is used in the synthesis of a functional gene product. These products are often proteins, but in non-protein coding genes such as ribosomal RNA , transfer RNA or small nuclear RNA genes, the product is a functional RNA...

.

External links

• Enhanceosome Molecule of the Month (February 2010) by David Goodsell

http://www.ncbi.nlm.nih.gov/pubmed/18206362 The enhaceosome by Daniel Panne