Crystallographic and mutational analysis of the CD40-CD154 complex and its implications for receptor activationAn, H.-J., Kim, Y.J., Song, D.H., Park, B.S., Kim, H.M., Lee, J.D., Paik, S.-G., Lee, J.-O., Lee, H.
(2011) J Biol Chem 286: 11226-11235
- PubMed: 21285457
- DOI: https://doi.org/10.1074/jbc.M110.208215
- Primary Citation of Related Structures:
- PubMed Abstract:
CD40 is a tumor necrosis factor receptor (TNFR) family protein that plays an important role in B cell development. CD154/CD40L is the physiological ligand of CD40. We have determined the crystal structure of the CD40-CD154 complex at 3.5 Å resolution. The binding site of CD40 is located in a crevice formed between two CD154 subunits. Charge complementarity plays a critical role in the CD40-CD154 interaction. Some of the missense mutations found in hereditary hyper-IgM syndrome can be mapped to the CD40-CD154 interface. The CD40 interaction area of one of the CD154 subunits is twice as large as that of the other subunit forming the binding crevice. This is because cysteine-rich domain 3 (CRD3) of CD40 has a disulfide bridge in an unusual position that alters the direction of the ladder-like structure of CD40. The Ser(132) loop of CD154 is not involved in CD40 binding but its substitution significantly reduces p38- and ERK-dependent signaling by CD40, whereas JNK-dependent signaling is not affected. These findings suggest that ligand-induced di- or trimerization is necessary but not sufficient for complete activation of CD40.
Department of Biology, College of Bioscience & Biotechnology, Chungnam National University, Daejon, Korea.