title: Structural insights into the Slit-Robo complex.
abstract: Slits are large multidomain leucine-rich repeat (LRR)-containing proteins that provide crucial guidance cues in neuronal and vascular development. More recently, Slits have been implicated in heart morphogenesis, angiogenesis, and tumor metastasis. Slits are ligands for the Robo (Roundabout) receptors, which belong to the Ig superfamily of transmembrane signaling molecules. The Slit-Robo interaction is mediated by the second LRR domain of Slit and the two N-terminal Ig domains of Robo, but the molecular details of this interaction and how it induces signaling remain unclear. Here we describe the crystal structures of the second LRR domain of human Slit2 (Slit2 D2), the first two Ig domains of its receptor Robo1 (Ig1-2), and the minimal complex between these proteins (Slit2 D2-Robo1 Ig1). Slit2 D2 binds with its concave surface to the side of Ig1 with electrostatic and hydrophobic contact regions mediated by residues that are conserved in other family members. Surface plasmon resonance experiments and a mutational analysis of the interface confirm that Ig1 is the primary domain for binding Slit2. These structures provide molecular insight into Slit-Robo complex formation and will be important for the development of novel cancer therapeutics.
authors.affiliation: European Molecular Biology Laboratory, 6 Rue Jules Horowitz, BP 181, 38042 Grenoble, France.
authors.forename: Cecile
authors.initials: C
authors.lastname: Morlot
authors.forename: Nicole M
authors.initials: NM
authors.lastname: Thielens
authors.forename: Raimond B G
authors.initials: RB
authors.lastname: Ravelli
authors.forename: Wieger
authors.initials: W
authors.lastname: Hemrika
authors.forename: Roland A
authors.initials: RA
authors.lastname: Romijn
authors.forename: Piet
authors.initials: P
authors.lastname: Gros
authors.forename: Stephen
authors.initials: S
authors.lastname: Cusack
authors.forename: Andrew A
authors.initials: AA
authors.lastname: McCarthy
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D006493:Heparin / Q000378:metabolism; D006801:Humans; D036341:Intercellular Signaling Peptides and Proteins / Q000737:chemistry* / Q000378:metabolism; D008954:Models, Biological; D008958:Models, Molecular; D008969:Molecular Sequence Data; D016296:Mutagenesis; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism; D017434:Protein Structure, Tertiary; D011971:Receptors, Immunologic / Q000737:chemistry* / Q000378:metabolism; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013329:Structure-Activity Relationship; D020349:Surface Plasmon Resonance; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein
chemical_list: D006493:Heparin; D036341:Intercellular Signaling Peptides and Proteins; D009419:Nerve Tissue Proteins; D011971:Receptors, Immunologic; D011994:Recombinant Proteins; D000097905:Roundabout Proteins; D000098552:Slit Homolog 2 Protein