The chromosomal association/dissociation of the chromatin insulator protein Cp190 of Drosophila melanogaster is mediated by the BTB/POZ domain and two acidic regions

BMC Cell Biol. 2010 Dec 31;11:101. doi: 10.1186/1471-2121-11-101.

Abstract

Background: Chromatin insulators or boundary elements are a class of functional elements in the eukaryotic genome. They regulate gene transcription by interfering with promoter-enhancer communication. The Cp190 protein of Drosophila melanogaster is essential to the function of at least three-types of chromatin insulator complexes organized by Su(Hw), CTCF and BEAF32.

Results: We mapped functional regions of Cp190 in vivo and identified three domains that are essential for the insulator function and for the viability of flies: the BTB/POZ domain, an aspartic acid-rich (D-rich) region and a C-terminal glutamic acid-rich (E-rich) region. Other domains including the centrosomal targeting domain and the zinc fingers are dispensable. The N-terminal CP190BTB-D fragment containing the BTB/POZ domain and the D-rich region is sufficient to mediate association with all three types of insulator complexes. The fragment however is not sufficient for insulator activity or viability. The Cp190 and CP190BTB-D are regulated differently in cells treated with heat-shock. The Cp190 dissociated from chromosomes during heat-shock, indicating that dissociation of Cp190 with chromosomes can be regulated. In contrast, the CP190BTB-D fragment didn't dissociate from chromosomes in the same heat-shocked condition, suggesting that the deleted C-terminal regions have a role in regulating the dissociation of Cp190 with chromosomes.

Conclusions: The N-terminal fragment of Cp190 containing the BTB/POZ domain and the D-rich region mediates association of Cp190 with all three types of insulator complexes and that the E-rich region of Cp190 is required for dissociation of Cp190 from chromosomes during heat-shock. The heat-shock-induced dissociation is strong evidence indicating that dissociation of the essential insulator protein Cp190 from chromosomes is regulated. Our results provide a mechanism through which activities of an insulator can be modulated by internal and external cues.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Animals
  • CCCTC-Binding Factor
  • Chromatin / genetics
  • Chromatin / metabolism*
  • Chromosomes, Insect / genetics
  • Chromosomes, Insect / metabolism*
  • DNA-Binding Proteins / genetics
  • DNA-Binding Proteins / metabolism
  • Drosophila Proteins / chemistry*
  • Drosophila Proteins / genetics
  • Drosophila Proteins / metabolism*
  • Drosophila melanogaster / chemistry
  • Drosophila melanogaster / genetics
  • Drosophila melanogaster / metabolism*
  • Eye Proteins / genetics
  • Eye Proteins / metabolism
  • Insulator Elements*
  • Microtubule-Associated Proteins / chemistry*
  • Microtubule-Associated Proteins / genetics
  • Microtubule-Associated Proteins / metabolism*
  • Nuclear Proteins / chemistry*
  • Nuclear Proteins / genetics
  • Nuclear Proteins / metabolism*
  • Protein Binding
  • Protein Structure, Tertiary
  • Repressor Proteins / genetics
  • Repressor Proteins / metabolism

Substances

  • BEAF-32 protein, Drosophila
  • CCCTC-Binding Factor
  • CP190 protein, Drosophila
  • CTCF protein, Drosophila
  • Chromatin
  • DNA-Binding Proteins
  • Drosophila Proteins
  • Eye Proteins
  • Microtubule-Associated Proteins
  • Nuclear Proteins
  • Repressor Proteins
  • su(Hw) protein, Drosophila