Part:BBa_J176000

hPCD

Polycomb chromodomain (PCD) from the human CBX8 protein (a.a. 1-63).
Alias: KAH01

Usage and Biology

Human PCD of CBX8 (orange) Crystal structure reported by Kaustov et al. 2011. Grey = H3 histone tail; Ball and stick = trimethylated lysine 9

• Protein Data Bank ID 3I91
• Mammalian expression vector recommended
• Protein domain; requires promoter, start codon, stop codon, and polyA signal for proper expression
  

The Polycomb chromodomain (PCD) is an ancient protein motif that is conserved in many multicellular organisms (from plants to insects to humans). The motif appears in proteins involved in regulating tissue identity, including the Drosophila (fruit fly) Pc protein, and the vertebrate Chromobox (CBX) protein family. PCD has an aromatic pocket that specifically recognizes the unfolded "tail" of histone H3 when the histone is trimethylated at lysine 27. Early characterization of this domain was done by Fischle et al (2003) and Min et al. (2003). The 3D structures for several human homologues have been reported (Kaustov et al., 2011).

In its native context, the PCD targets gene silencing proteins to genes marked with histone methylation. The PCD domain can be fused to Biobrick proteins to recruit other protein domains, such as synthetic transcriptional activators, to sites of histone methylation in human cells (Haynes and Silver, 2011). Note that the solved 3D structure shows the human CBX8 PCD bound to methylated histone H3 lysine 9, but biochemical tests have shown that it prefers methylated lysine 27.

REFERENCES:

1. Fischle, W, Wang, Y, Jacobs, SA, Kim, Y, Allis, CD, Khorasanizadeh, S. (2003) Molecular basis for the discrimination of repressive methyl-lysine marks in histone H3 by Polycomb and HP1 chromodomains. Genes Dev. 17:1870-1881.
2. Min, J, Zhang, Y, Xu, RM. (2003) Structural basis for the specific binding of Polycomb chromodomain to histone H3 methylated at Lys 27. Genes Dev. 17:1823-1828.
3. Haynes, KA, Silver, PA. (2011) Synthetic reversal of epigenetic silencing. J Biol Chem. 286:27176-27182.
4. Kaustov, L., Ouyang, H., Amaya, M., Lemak, A., Nady, N., Duan, S., Wasney, G.A., Li, Z., Vedadi, M., Schapira, M., Min, J., Arrowsmith, C.H. (2011) Recognition and specificity determinants of the human cbx chromodomains. J Biol Chem. 286:521-529.

Sequence and Features

Assembly Compatibility:

• 10
  COMPATIBLE WITH RFC[10]
• 12
  COMPATIBLE WITH RFC[12]
• 21
  COMPATIBLE WITH RFC[21]
• 23
  COMPATIBLE WITH RFC[23]
• 25
  COMPATIBLE WITH RFC[25]
• 1000
  COMPATIBLE WITH RFC[1000]