1R8U: NMR Structure of CBP Taz1cited2 Complex

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.
PDB ID: 1R8UDownload
MMDB ID: 26902
PDB Deposition Date: 2003/10/28
Updated in MMDB: 2007/11 
Experimental Method:
solution nmr
Source Organism:
Mus musculus
Similar Structures:
Molecular Components in 1R8U
Label Count Molecule
Proteins (2 molecules)
Cbp/p300-interacting Transactivator 2(Gene symbol: CITED2)
Molecule annotation
Creb-binding Protein(Gene symbol: Crebbp)
Molecule annotation
Chemicals (3 molecules)
* Click molecule labels to explore molecular sequence information.

Citing MMDB