Download MendeleyX-ray crystal structure of proto-oncogene product c-Rel bound to the CD28 response element of IL-2.
Huang, D.B., Chen, Y.Q., Ruetsche, M., Phelps, C.B., Ghosh, G.(2001) Structure 9: 669-678
- PubMed: 11587641
- DOI: https://doi.org/10.1016/s0969-2126(01)00635-9
- Primary Citation of Related Structures:
1GJI - PubMed Abstract:
The proto-oncogene product c-Rel is a Rel/NF-kappaB family transcription factor that plays a critical role in lymphoid cell development and mediates CD28-induced expression of interleukin 2 (IL-2). The CD28 response element (CD28RE) in the IL-2 enhancer is nonameric and similar to the kappaB DNA target sites recognized by p65 homodimers. We have determined and refined the X-ray crystal structure of the c-Rel homodimer complexed to the CD28RE DNA site, 5'-AGAAATTCC-3', to 2.85 A resolution. The c-Rel homodimer binds CD28RE in a mode similar to that observed in the p65/IL-8 kappaB crystallographic complex. Binding studies reveal that the c-Rel homodimer recognizes the CD28RE with higher affinity as compared to other canonical kappaB sequences despite the nonconsensus A:T base pair at the 5' end of the CD28RE. Preferential recognition of the CD28RE by c-Rel results from the direct contacts between the protein and the DNA as well as intrasubunit interactions between the beta(f)-beta(g) loop in the dimerization domain and the DNA-contacting loop L1 of the N-terminal domain. Not only do these loops have different conformations in other Rel/DNA crystallographic complexes, but they also contain two of the five oncogenic point mutations found in v-Rel. The current structure indicates that a non-DNA-contacting loop in the dimerization domain and the DNA-contacting loop L1 may play critical roles in defining affinity and specificity. Two amino acid changes in these segments may account for the differential DNA binding by v-Rel as compared to that of c-Rel.
Organizational Affiliation:
Department of Chemistry and Biochemistry, University of California, San Diego, La Jolla, CA 92093, USA.
