Structure of a Domain-Swapped FOXP3 Dimer on DNA and Its Function in Regulatory T Cells.Bandukwala, H.S., Wu, Y., Feuerer, M., Chen, Y., Barboza, B., Ghosh, S., Stroud, J.C., Benoist, C., Mathis, D., Rao, A., Chen, L.
(2011) Immunity 34: 479-491
- PubMed: 21458306
- DOI: https://doi.org/10.1016/j.immuni.2011.02.017
- Primary Citation of Related Structures:
- PubMed Abstract:
The transcription factor FOXP3 is essential for the suppressive function of regulatory T cells that are required for maintaining self-tolerance. We have solved the crystal structure of the FOXP3 forkhead domain as a ternary complex with the DNA-binding domain of the transcription factor NFAT1 and a DNA oligonucleotide from the interleukin-2 promoter. A striking feature of this structure is that FOXP3 forms a domain-swapped dimer that bridges two molecules of DNA. Structure-guided or autoimmune disease (IPEX)-associated mutations in the domain-swap interface diminished dimer formation by the FOXP3 forkhead domain without compromising FOXP3 DNA binding. These mutations also eliminated T cell-suppressive activity conferred by FOXP3, both in vitro and in a murine model of autoimmune diabetes in vivo. We conclude that FOXP3-mediated suppressor function requires dimerization through the forkhead domain and that mutations in the dimer interface can lead to the systemic autoimmunity observed in IPEX patients.
Immune Disease Institute and Program in Cellular and Molecular Medicine, Children's Hospital, Boston, MA 02115, USA.