title: Structural basis for negative regulation of hypoxia-inducible factor-1alpha by CITED2.
abstract: Expression of hypoxia-responsive genes is mediated by the heterodimeric transcription factor hypoxia-inducible factor-1 (HIF-1) in complex with the p300/CREB-binding protein (p300/CBP) transcriptional coactivator. The protein CITED2, which binds p300/CBP, is thought to be a negative regulator of HIF-1 transactivation. We show that the CITED2 transactivation domain (TAD) disrupts a complex of the HIF-1alpha C-terminal TAD (C-TAD) and the cysteine-histidine-rich 1 (CH1) domain of p300/CBP by binding CH1 with high affinity. The high-resolution solution structure of the CITED2 TAD-p300 CH1 complex shows that the CITED2 TAD, like the HIF-1alpha C-TAD, folds on a helical, Zn2+-containing CH1 scaffold. The CITED2 TAD binds a different, more extensive surface of CH1 than does the HIF-1alpha C-TAD. However, a conserved 'LPXL' sequence motif in CITED2 and HIF-1alpha interacts with an overlapping binding site on CH1. Mutation of the LPEL sequence in full-length CITED2 abolishes p300 binding in vivo. These findings reveal that CITED2 regulates HIF-1 by competing for a hot spot on the p300 CH1 domain.
authors.affiliation: Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center, 41 Avenue Louis Pasteur, Boston, Massachusetts 02115, USA.
authors.forename: Steven J
authors.initials: SJ
authors.lastname: Freedman
authors.forename: Zhen-Yu J
authors.initials: ZY
authors.lastname: Sun
authors.forename: Andrew L
authors.initials: AL
authors.lastname: Kung
authors.forename: Dennis S
authors.initials: DS
authors.lastname: France
authors.forename: Gerhard
authors.initials: G
authors.lastname: Wagner
authors.forename: Michael J
authors.initials: MJ
authors.lastname: Eck
mesh_terms: D020816:Amino Acid Motifs; D000595:Amino Acid Sequence; D000818:Animals; D002942:Circular Dichroism; D004268:DNA-Binding Proteins; D006801:Humans; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D008958:Models, Molecular; D008969:Molecular Sequence Data; D019906:Nuclear Magnetic Resonance, Biomolecular; D011485:Protein Binding; D011487:Protein Conformation; D012097:Repressor Proteins; D017386:Sequence Homology, Amino Acid; D015534:Trans-Activators / Q000378:metabolism / Q000502:physiology*; D014157:Transcription Factors / Q000737:chemistry* / Q000378:metabolism / Q000502:physiology*
chemical_list: C486381:CITED2 protein, human; D004268:DNA-Binding Proteins; C497442:HIF1A protein, human; D051795:Hypoxia-Inducible Factor 1, alpha Subunit; D012097:Repressor Proteins; D015534:Trans-Activators; D014157:Transcription Factors