title: Artemin crystal structure reveals insights into heparan sulfate binding.
abstract: Artemin (ART) promotes the growth of developing peripheral neurons by signaling through a multicomponent receptor complex comprised of a transmembrane tyrosine kinase receptor (cRET) and a specific glycosylphosphatidylinositol-linked co-receptor (GFRalpha3). Glial cell line-derived neurotrophic factor (GDNF) signals through a similar ternary complex but requires heparan sulfate proteoglycans (HSPGs) for full activity. HSPG has not been demonstrated as a requirement for ART signaling. We crystallized ART in the presence of sulfate and solved its structure by isomorphous replacement. The structure reveals ordered sulfate anions bound to arginine residues in the pre-helix and amino-terminal regions that were organized in a triad arrangement characteristic of heparan sulfate. Three residues in the pre-helix were singly or triply substituted with glutamic acid, and the resulting proteins were shown to have reduced heparin-binding affinity that is partly reflected in their ability to activate cRET. This study suggests that ART binds HSPGs and identifies residues that may be involved in HSPG binding.
authors.affiliation: Department of Drug Discovery, Biogen Idec, Inc., 12 Cambridge Center, Cambridge, Massachusetts 02142, USA. laura.silvian@biogenidec.com
authors.forename: Laura
authors.initials: L
authors.lastname: Silvian
authors.forename: Ping
authors.initials: P
authors.lastname: Jin
authors.forename: Paul
authors.initials: P
authors.lastname: Carmillo
authors.forename: P Ann
authors.initials: PA
authors.lastname: Boriack-Sjodin
authors.forename: Carolyn
authors.initials: C
authors.lastname: Pelletier
authors.forename: Mia
authors.initials: M
authors.lastname: Rushe
authors.forename: BangJian
authors.initials: B
authors.lastname: Gong
authors.forename: Dinah
authors.initials: D
authors.lastname: Sah
authors.forename: Blake
authors.initials: B
authors.lastname: Pepinsky
authors.forename: Anthony
authors.initials: A
authors.lastname: Rossomando
mesh_terms: D000595:Amino Acid Sequence; D000818:Animals; D001665:Binding Sites; D002417:Cattle; D003461:Crystallography; D006497:Heparan Sulfate / Q000737:chemistry*; D006801:Humans; D051379:Mice; D008969:Molecular Sequence Data; D009154:Mutation; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000235:genetics; D011487:Protein Conformation; D017433:Protein Structure, Secondary; D051381:Rats
chemical_list: D006497:Heparan Sulfate; D009419:Nerve Tissue Proteins; C490886:ARTN protein, human