4c4m
Crystal structure of the Sonic Hedgehog-chondroitin-4-sulphate complex
Structural highlights
FunctionSHH_MOUSE Binds to the patched (PTC) receptor, which functions in association with smoothened (SMO), to activate the transcription of target genes. In the absence of SHH, PTC represses the constitutive signaling activity of SMO. Also regulates another target, the gli oncogene. Intercellular signal essential for a variety of patterning events during development: signal produced by the notochord that induces ventral cell fate in the neural tube and somites, and the polarizing signal for patterning of the anterior-posterior axis of the developing limb bud. Displays both floor plate- and motor neuron-inducing activity. The threshold concentration of N-product required for motor neuron induction is 5-fold lower than that required for floor plate induction (By similarity).[1] Publication Abstract from PubMedHedgehog (Hh) morphogens play fundamental roles during embryogenesis and adulthood, in health and disease. Multiple cell surface receptors regulate the Hh signaling pathway. Among these, the glycosaminoglycan (GAG) chains of proteoglycans shape Hh gradients and signal transduction. We have determined crystal structures of Sonic Hh complexes with two GAGs, heparin and chondroitin sulfate. The interaction determinants, confirmed by site-directed mutagenesis and binding studies, reveal a previously not identified Hh site for GAG binding, common to all Hh proteins. The majority of Hh residues forming this GAG-binding site have been previously implicated in developmental diseases. Crystal packing analysis, combined with analytical ultracentrifugation of Sonic Hh-GAG complexes, suggests a potential mechanism for GAG-dependent Hh multimerization. Taken together, these results provide a direct mechanistic explanation of the observed correlation between disease and impaired Hh gradient formation. Moreover, GAG binding partially overlaps with the site of Hh interactions with an array of protein partners including Patched, hedgehog interacting protein, and the interference hedgehog protein family, suggesting a unique mechanism of Hh signaling modulation. Structural insights into proteoglycan-shaped Hedgehog signaling.,Whalen DM, Malinauskas T, Gilbert RJ, Siebold C Proc Natl Acad Sci U S A. 2013 Oct 8;110(41):16420-16425. Epub 2013 Sep 23. PMID:24062467[2] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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