Structural basis for negative regulation of hypoxia-inducible factor-1α by CITED2

• Published in: Nature structural biology Vol. 10; no. 7; pp. 504 - 512
• Main Authors: Eck, Michael J, Freedman, Steven J, Sun, Zhen-Yu J, Kung, Andrew L, France, Dennis S, Wagner, Gerhard
• Format: Journal Article
• Language: English
• Published: 01-07-2003
• Subjects: CITED2 protein; CREB-binding protein
• ISSN: 1072-8368; 2331-365X
• DOI: 10.1038/nsb936

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-1 alpha 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-1 alpha C-TAD, folds on a helical, Zn super(2+)-containing CH1 scaffold. The CITED2 TAD binds a different, more extensive surface of CH1 than does the HIF-1 alpha C-TAD. However, a conserved 'LPXL' sequence motif in CITED2 and HIF-1 alpha 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.