1CI6

TRANSCRIPTION FACTOR ATF4-C/EBP BETA BZIP HETERODIMER

Summary for 1CI6

• Entry DOI: 10.2210/pdb1ci6/pdb
• Descriptor: TRANSCRIPTION FACTOR ATF-4, TRANSCRIPTION FACTOR C/EBP BETA, FE (III) ION, ... (5 entities in total)
• Functional Keywords: transcription factor, bzip, transcription
• Biological source: Homo sapiens (human); More
• Cellular location: Cytoplasm: P18848; Nucleus: P28033
• Total number of polymer chains: 2
• Total formula weight: 15463.41

Authors

Podust, L.M.,Kim, Y. (deposition date: 1999-04-07, release date: 2000-12-04, Last modification date: 2023-08-09)

Primary citation

Podust, L.M.,Krezel, A.M.,Kim, Y.
Crystal structure of the CCAAT box/enhancer-binding protein beta activating transcription factor-4 basic leucine zipper heterodimer in the absence of DNA
J.Biol.Chem., 276:505-513, 2001

PubMed Abstract: The crystal structure of the heterodimer formed by the basic leucine zipper (bZIP) domains of activating transcription factor-4 (ATF4) and CCAAT box/enhancer-binding protein beta (C/EBP beta), from two different bZIP transcription factor families, has been determined and refined to 2.6 A. The structure shows that the heterodimer forms an asymmetric coiled-coil. Even in the absence of DNA, the basic region of ATF4 forms a continuous alpha-helix, but the basic region of C/EBP beta is disordered. Proteolysis, electrophoretic mobility shift assay, circular dichroism, and NMR analyses indicated that (i) the bZIP domain of ATF4 is a disordered monomer and forms a homodimer upon binding to the DNA target; (ii) the bZIP domain of ATF4 forms a heterodimer with the bZIP domain of C/EBP beta that binds the cAMP response element, but not CCAAT box DNA, with high affinity; and (iii) the basic region of ATF4 has a higher alpha-helical propensity than that of C/EBP beta. These results suggest that the degree of ordering of the basic region and the fork and the dimerization properties of the leucine zipper combine to distinguish the structurally similar bZIP domains of ATF4 and C/EBP beta with respect to DNA target sequence. This study provides insight into the mechanism by which dimeric bZIP transcription factors discriminate between closely related but distinct DNA targets.

PubMed: 11018027
DOI: 10.1074/jbc.M005594200

Experimental method

X-RAY DIFFRACTION (2.6 Å)