Molecular recognition of BMP-2 and BMP receptor IA

Abstract

Bone morphogenetic protein-2 (BMP-2) and other members of the TGF-beta superfamily regulate the development, maintenance and regeneration of tissues and organs. Binding epitopes for these extracellular signaling proteins have been defined, but hot spots specifying binding affinity and specificity have so far not been identified. In this study, mutational and structural analyses show that epitopes of BMP-2 and the BRIA receptor form a new type of protein-protein interface. The main chain atoms of Leu 51 and Asp53 of BMP-2 represent a hot spot of binding to BRIA. The BMP-2 variant L51P was deficient in type I receptor binding only, whereas its overall structure and its binding to type II receptors and modulator proteins, such as noggin, were unchanged. Thus, the L51P substitution converts BMP-2 into a receptor-inactive inhibitor of noggin. These results are relevant for other proteins of the TGF-beta superfamily and provide useful clues for structure-based drug design.

Effective Inhibition of Bone Morphogenetic Protein Function by Highly Specific Llama-Derived Antibodies

“…The docking model showed that these nonconserved residues are involved in binding with residues from the CDR2 and CDR3 of C4, therefore validating its BMP4 specificity. Interestingly, residues located in loop 2 of the groove epitope represent a hotspot of binding to BMPR1 a (36), which could explain the high affinity binding observed for C4C4. C8-like VHHs target the hydrophobic pocket of the wrist epitope of BMP2 and BMP4, an epitope formed by residues from both monomers.…”

“…Noggin and BMPR1 a were used as controls and bound all BMPs, concurring with published observations (Table 1; refs. 36,37). Among all measured monomers, C8 and E7 were the only ones binding to BMP2 (Fig.…”

von Willebrand Factor Type C Domain-containing Proteins Regulate Bone Morphogenetic Protein Signaling through Different Recognition Mechanisms

“…Biological Activity in Cell Lines-Alkaline phosphatase (ALP) activity was determined in serum-starved C2C12 cells as described (8,10). Inhibition of BMP-2-induced ALP activity by modulators was assessed by incubating C2C12 cells with different concentrations of modulators plus 10 nM BMP-2.…”

“…Biosensor Interaction Analysis-The binding of BMPs/modulators was recorded on a BIAcore 2000 system (Amersham Biosciences Biosensor) as described (8,10 Co-immunoprecipitation-Immunoprecipitation was performed as described (21,33). Briefly, the modulator proteins containing His 6 tag were incubated with BMP-2 in 1 ml of binding buffer, followed by 2-5 g/ml anti-His tag antibody (Invitrogen).…”

“…Of 10 hydrogen bonds occurring in the BMP-2-BMPR-IAecd contact, only two in the center contribute to affinity. A BMP-2 L51P mutant, which has lost one of the central hydrogen bonds due to the introduced proline, lacks high affinity binding to BMPR-IA but has retained wild type affinity for BMP modulator proteins, like noggin and gremlin (10).…”