The crystal structure of the BMP-2:BMPR-IA complex and the generation of BMP-2 antagonists.

摘要: BACKGROUND Bone morphogenetic proteins (BMPs) and growth differentiation factors (GDFs) belong to the large transforming factor-beta (TGF-beta) superfamily of multifunctional cytokines. Signaling BMPs requires binding BMP cell surface receptors BMPR-IA, BMPR-IB, BMPR-II. Similar other cytokines, members TGF-beta exhibit stringent specificity in their ligand-receptor interactions, which may be a reason for qualitative quantitative differences cellular responses. To understand how GDFs activate receptors, it is important determine structure mechanisms complexes. We have used BMP-2 as key representative identify epitopes type I II receptor by mutational interaction analyses solved crystal BMP2:BMPR-IA ectodomain complex. METHODS amino acid side chains involved binding, collection vitro mutagenized human variants was prepared subjected with use ectodomains BMPR-II, ActR-II immobilized on biosensor system. The biological activity measured dependent expression alkaline phosphatase (ALP) C2C12 cells. For crystallization, complex BMPR-IA formed solution, purified, crystallized described(12). RESULTS analysis identified distinct binding. Because TGF-beta-like has been compared that an open hand, epitope was-on basis its location-termed "wrist" epitope. BMP-2:BMPR-IA revealed feature interaction: hydrophobic residue (Phe85) within patch fit into pocket composed residues both monomers. A second alanine mutagenesis scanning termed "knuckle" location outer "finger" segments BMP-2. Mutations either wrist or knuckle produced altered activities. Variants antagonistic properties were exclusively generated mutations CONCLUSIONS AND CLINICAL RELEVANCE identification characterization two provide new insight primary steps BMP-receptor activation. structural similarities between superfamily, can assumed data presented this work are transferable systems. association various diseases, generation antagonists might generate potent tools basic research therapeutic approaches.