EMD-26475

Single-particle
3.28 Å
EMD-26475 Deposition: 22/03/2022
Map released: 28/09/2022
Last modified: 23/10/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links

EMD-26475

Structure of a metalloprotease in complex with its substrate.

EMD-26475

Single-particle
3.28 Å
EMD-26475 Deposition: 22/03/2022
Map released: 28/09/2022
Last modified: 23/10/2024
Overview 3D View Sample Experiment Validation Volume Browser Additional data Links
Sample Organism: Homo sapiens
Sample: Complex of PAPP-A with IGFBP5
Fitted models: 7ufg (Avg. Q-score: 0.443)

Deposition Authors: Judge RA , Jain R, Hao Q , Ouch C , Sridar J, Smith CL, Wang JCK , Eaton D
Structure of the PAPP-ABP5 complex reveals mechanism of substrate recognition
PUBMED: 36127359
DOI: doi:10.1038/s41467-022-33175-2
ISSN: 2041-1723
Abstract:
Insulin-like growth factor (IGF) signaling is highly conserved and tightly regulated by proteases including Pregnancy-Associated Plasma Protein A (PAPP-A). PAPP-A and its paralog PAPP-A2 are metalloproteases that mediate IGF bioavailability through cleavage of IGF binding proteins (IGFBPs). Here, we present single-particle cryo-EM structures of the catalytically inactive mutant PAPP-A (E483A) in complex with a peptide from its substrate IGFBP5 (PAPP-ABP5) and also in its substrate-free form, by leveraging the power of AlphaFold to generate a high quality predicted model as a starting template. We show that PAPP-A is a flexible trans-dimer that binds IGFBP5 via a 25-amino acid anchor peptide which extends into the metalloprotease active site. This unique IGFBP5 anchor peptide that mediates the specific PAPP-A-IGFBP5 interaction is not found in other PAPP-A substrates. Additionally, we illustrate the critical role of the PAPP-A central domain as it mediates both IGFBP5 recognition and trans-dimerization. We further demonstrate that PAPP-A trans-dimer formation and distal inter-domain interactions are both required for efficient proteolysis of IGFBP4, but dispensable for IGFBP5 cleavage. Together the structural and biochemical studies reveal the mechanism of PAPP-A substrate binding and selectivity.