Download MendeleyMolecular Mechanism of CCAAT-Enhancer Binding Protein Recruitment by the TRIB1 Pseudokinase.
Murphy, J.M., Nakatani, Y., Jamieson, S.A., Dai, W., Lucet, I.S., Mace, P.D.(2015) Structure 23: 2111-2121
- PubMed: 26455797
- DOI: https://doi.org/10.1016/j.str.2015.08.017
- Primary Citation of Related Structures:
5CEK, 5CEM - PubMed Abstract:
CCAAT-enhancer binding proteins (C/EBPs) are transcription factors that play a central role in the differentiation of myeloid cells and adipocytes. Tribbles pseudokinases govern levels of C/EBPs by recruiting them to the COP1 ubiquitin ligase for ubiquitination. Here, we present the first crystal structure of a Tribbles protein, which reveals a catalytically inactive TRIB1 pseudokinase domain with a unique adaptation in the αC helix. A second crystal structure and biophysical studies of TRIB1 with its C-terminal extension, which includes the COP1-binding motif, show that the C-terminal extension is sequestered at a site formed by the modified TRIB1 αC helix. In addition, we have identified and characterized the TRIB1 substrate-recognition sequence within C/EBPα, which is evolutionarily conserved in C/EBP transcription factors. Binding studies indicate that C/EBPα recruitment is weaker in the presence of the C-terminal COP1-binding motif, but the magnitude of this effect suggests that the two bind distinct rather directly overlapping binding sites.
Organizational Affiliation:
The Walter and Eliza Hall Institute of Medical Research, Parkville, VIC 3052, Australia; Department of Medical Biology, University of Melbourne, Parkville, VIC 3052, Australia.
