Encyclopedia of Systems Biology

2013 Edition
| Editors: Werner Dubitzky, Olaf Wolkenhauer, Kwang-Hyun Cho, Hiroki Yokota

PIC Disassembly

Reference work entry
DOI: https://doi.org/10.1007/978-1-4419-9863-7_1623

Synonyms

Definition

HP1 (heterochromatin protein 1)-family proteins are widely conserved among eukaryotes, with the exception of budding yeast. They all contain a chromodomain that binds directly to di- or tri-methylated histone H3 lysine 9 (H3K9me2 or H3K9me3), an established marker of silenced chromatin. In addition, the artificial recruitment of these proteins to promoter regions results in gene silencing. Therefore, it is likely that HP1 proteins can repress transcription.

In vitro transcription experiments using chromatin templates have revealed that human HP1 proteins (HP1α, β, and γ) repress transcription by preventing the binding of TFIIB, TFIID, TFIIE, TFIIH, RNAPII, and specific subunits of the Mediator to the promoter (Smallwood et al. 2008). Remarkably, these HP1 proteins can also evict TFIID, RNAPII, and specific subunits of the Mediator, but not TFIIB, TFIIE, or TFIIH, from the preassembled PIC. Given that the HP1 proteins do...

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References

  1. Johnson KM, Carey M (2003) Assembly of a mediator/TFIID/TFIIA complex bypasses the need for an activator. Curr Biol 13(9):772–777PubMedGoogle Scholar
  2. Kwon SH, Florens L, Swanson SK, Washburn MP, Abmayr SM, Workman JL (2010) Heterochromatin protein 1 (HP1) connects the FACT histone chaperone complex to the phosphorylated CTD of RNA polymerase II. Genes Dev 24(19):2133–2145PubMedGoogle Scholar
  3. Smallwood A, Black JC, Tanese N, Pradhan S, Carey M (2008) HP1-mediated silencing targets Pol II coactivator complexes. Nat Struct Mol Biol 15(3):318–320PubMedGoogle Scholar

Copyright information

© Springer Science+Business Media, LLC 2013

Authors and Affiliations

  1. 1.Department of Supramolecular BiologyGraduate School of Nanobioscience, Yokohama City UniversityYokohamaJapan