Interaction of the TAZ1 domain of the CREB-binding protein with the activation domain of CITED2: regulation by competition between intrinsically unstructured ligands for non-identical binding sites

J Biol Chem. 2004 Jan 23;279(4):3042-9. doi: 10.1074/jbc.M310348200. Epub 2003 Oct 31.


The TAZ1 domain of the homologous transcriptional coactivators CREB-binding protein (CBP) and p300 forms a complex with CITED2 (CBP/p300-interacting transactivator with ED-rich tail), inhibiting the activity of the hypoxia inducible factor (HIF-1alpha) and thereby attenuating the cellular response to low tissue oxygen concentration. We report the NMR structure of the CBP TAZ1 domain bound to the activation domain of CIT-ED2. The structure of TAZ1, consisting of four alpha-helices (alpha(1)-alpha(4)) stabilized by three zinc atoms, is very similar in the CITED2 and HIF-1alpha complexes. The activation domain of CITED2 is unstructured when free and folds upon binding, forming a helix (termed alpha(A)) and an extended structure that wraps around TAZ1. The CITED2 alpha(A) helix packs in the TAZ1 alpha(1)/alpha(4) interface, a site that forms weak interactions with the poorly defined aminoterminal alpha-helix of HIF-1alpha. CITED2 and HIF-1alpha both contain a four residue motif, LP(E/Q)L, which binds in the TAZ1 alpha(1)/alpha(2)/alpha(3) junction in each complex. The carboxyl-terminal region of CITED2 forms an extended structure with hydrophobic contacts in the TAZ1 alpha(1)/alpha(3) interface in the site occupied by the HIF-1alpha alpha(B) helix. CITED2 does not bind at all to the TAZ1 site occupied by the HIF-1alpha carboxyl-terminal helix. The HIF-1alpha and CITED2 domains utilize partly overlapping surfaces of TAZ1 to achieve high affinity binding and to compete effectively with each other for interaction with CBP/p300; CITED2 and HIF-1alpha use these binding sites differently to maintain similar binding affinities in order to displace each other in a feedback loop during the hypoxic response.

Publication types

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

MeSH terms

  • Amino Acid Sequence
  • Animals
  • Binding Sites
  • CREB-Binding Protein
  • DNA-Binding Proteins / chemistry
  • DNA-Binding Proteins / metabolism*
  • Humans
  • Hypoxia-Inducible Factor 1
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Ligands
  • Mice
  • Models, Molecular
  • Molecular Sequence Data
  • Nuclear Proteins / chemistry
  • Nuclear Proteins / metabolism*
  • Protein Binding
  • Protein Conformation
  • Protein Structure, Tertiary
  • Repressor Proteins / chemistry
  • Repressor Proteins / metabolism*
  • Sequence Alignment
  • Trans-Activators / chemistry
  • Trans-Activators / metabolism*
  • Transcription Factors*


  • CITED2 protein, human
  • Cited2 protein, mouse
  • DNA-Binding Proteins
  • HIF1A protein, human
  • Hif1a protein, mouse
  • Hypoxia-Inducible Factor 1
  • Hypoxia-Inducible Factor 1, alpha Subunit
  • Ligands
  • Nuclear Proteins
  • Repressor Proteins
  • Trans-Activators
  • Transcription Factors
  • CREB-Binding Protein
  • CREBBP protein, human
  • Crebbp protein, mouse

Associated data

  • PDB/1R8U