title: A single residue of GDF-5 defines binding specificity to BMP receptor IB.
abstract: Growth and differentiation factor 5 (GDF-5), a member of the TGF-beta superfamily, is involved in many developmental processes, like chondrogenesis and joint formation. Mutations in GDF-5 lead to diseases, e.g. chondrodysplasias like Hunter-Thompson, Grebe and DuPan syndromes and brachydactyly. Similar to other TGF-beta superfamily members, GDF-5 transmits signals through binding to two different types of membrane-bound serine-/threonine-kinase receptors termed type I and type II. In contrast to the large number of ligands, only seven type I and five type II receptors have been identified to date, implicating a limited promiscuity in ligand-receptor interaction. However, in contrast to other members of the TGF-beta superfamily, GDF-5 shows a pronounced specificity in type I receptor interaction in cross-link experiments binding only to BMP receptor IB (BMPR-IB). In mice, deletion of either GDF-5 or BMPR-IB results in a similar phenotype, indicating that GDF-5 signaling is highly dependent on BMPR-IB. Here, we demonstrate by biosensor analysis that GDF-5 also binds to BMP receptor IA (BMPR-IA) but with approximately 12-fold lower affinity. Structural and mutational analyses revealed a single residue of GDF-5, Arg57 located in the pre-helix loop, being solely responsible for the high binding specificity to BMPR-IB. In contrast to wild-type GDF-5, variant GDF-5R57A interacts with BMPR-IA and BMPR-IB with a comparable high binding affinity. These results provide important insights into how receptor-binding specificity is generated at the molecular level and might be useful for the generation of receptor subtype specific activators or inhibitors.
authors.affiliation: Lehrstuhl für Physiologische Chemie II, Theodor-Boveri Institut für Biowissenschaften (Biozentrum) der Universität Würzburg, Am Hubland, D-97074 Würzburg, Germany.
authors.forename: Joachim
authors.initials: J
authors.lastname: Nickel
authors.forename: Alexander
authors.initials: A
authors.lastname: Kotzsch
authors.forename: Walter
authors.initials: W
authors.lastname: Sebald
authors.forename: Thomas D
authors.initials: TD
authors.lastname: Mueller
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001120:Arginine / Q000737:chemistry; D001665:Binding Sites; D052005:Bone Morphogenetic Protein Receptors, Type I; D019485:Bone Morphogenetic Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D045744:Cell Line, Tumor; D055428:Growth Differentiation Factor 5; D006801:Humans; D051379:Mice; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009154:Mutation; D017346:Protein Serine-Threonine Kinases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D017978:Receptors, Growth Factor / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism
chemical_list: D019485:Bone Morphogenetic Proteins; C525893:GDF5 protein, human; C525894:Gdf5 protein, mouse; D055428:Growth Differentiation Factor 5; D017978:Receptors, Growth Factor; D001120:Arginine; D017346:Protein Serine-Threonine Kinases; C498211:BMPR1A protein, human; C498214:BMPR1B protein, human; C498212:Bmpr1a protein, mouse; C498215:Bmpr1b protein, mouse; D052005:Bone Morphogenetic Protein Receptors, Type I