7PGM image
Entry Detail
PDB ID:
7PGM
Title:
HHIP-C in complex with heparin
Biological Source:
Source Organism:
Host Organism:
PDB Version:
Deposition Date:
2021-08-14
Release Date:
2021-12-15
Method Details:
Experimental Method:
Resolution:
2.70 Å
R-Value Free:
0.23
R-Value Work:
0.21
R-Value Observed:
0.21
Space Group:
C 1 2 1
Macromolecular Entities
Polymer Type:polypeptide(L)
Description:Hedgehog-interacting protein
Chain IDs:A, B, C
Chain Length:470
Number of Molecules:3
Biological Source:Homo sapiens
Ligand Molecules
Primary Citation
Hedgehog-Interacting Protein is a multimodal antagonist of Hedgehog signalling.
Nat Commun 12 7171 7171 (2021)
PMID: 34887403 DOI: 10.1038/s41467-021-27475-2

Abstact

Hedgehog (HH) morphogen signalling, crucial for cell growth and tissue patterning in animals, is initiated by the binding of dually lipidated HH ligands to cell surface receptors. Hedgehog-Interacting Protein (HHIP), the only reported secreted inhibitor of Sonic Hedgehog (SHH) signalling, binds directly to SHH with high nanomolar affinity, sequestering SHH. Here, we report the structure of the HHIP N-terminal domain (HHIP-N) in complex with a glycosaminoglycan (GAG). HHIP-N displays a unique bipartite fold with a GAG-binding domain alongside a Cysteine Rich Domain (CRD). We show that HHIP-N is required to convey full HHIP inhibitory function, likely by interacting with the cholesterol moiety covalently linked to HH ligands, thereby preventing this SHH-attached cholesterol from binding to the HH receptor Patched (PTCH1). We also present the structure of the HHIP C-terminal domain in complex with the GAG heparin. Heparin can bind to both HHIP-N and HHIP-C, thereby inducing clustering at the cell surface and generating a high-avidity platform for SHH sequestration and inhibition. Our data suggest a multimodal mechanism, in which HHIP can bind two specific sites on the SHH morphogen, alongside multiple GAG interactions, to inhibit SHH signalling.

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Primary Citation of related structures