title: Structural Characterization of the Extracellular Domain of CASPR2 and Insights into Its Association with the Novel Ligand Contactin1.
abstract: Contactin-associated protein-like 2 (CNTNAP2) encodes for CASPR2, a multidomain single transmembrane protein belonging to the neurexin superfamily that has been implicated in a broad range of human phenotypes including autism and language impairment. Using a combination of biophysical techniques, including small angle x-ray scattering, single particle electron microscopy, analytical ultracentrifugation, and bio-layer interferometry, we present novel structural and functional data that relate the architecture of the extracellular domain of CASPR2 to a previously unknown ligand, Contactin1 (CNTN1). Structurally, CASPR2 is highly glycosylated and has an overall compact architecture. Functionally, we show that CASPR2 associates with micromolar affinity with CNTN1 but, under the same conditions, it does not interact with any of the other members of the contactin family. Moreover, by using dissociated hippocampal neurons we show that microbeads loaded with CASPR2, but not with a deletion mutant, co-localize with transfected CNTN1, suggesting that CNTN1 is an endogenous ligand for CASPR2. These data provide novel insights into the structure and function of CASPR2, suggesting a complex role of CASPR2 in the nervous system.
authors.affiliation: From the Child Health Institute of New Jersey and Departments of Neuroscience and Cell Biology and.
authors.forename: Eva N
authors.initials: EN
authors.lastname: Rubio-Marrero
authors.affiliation: From the Child Health Institute of New Jersey and Departments of Neuroscience and Cell Biology and.
authors.forename: Gabriele
authors.initials: G
authors.lastname: Vincelli
authors.affiliation: the School of Molecular Bioscience, University of Sydney, New South Wales 2006, Australia.
authors.forename: Cy M
authors.initials: CM
authors.lastname: Jeffries
authors.affiliation: the Structural Biology Programme, Central European Institute of Technology, Masaryk University, 62500 Brno, Czech Republic.
authors.forename: Tanvir R
authors.initials: TR
authors.lastname: Shaikh
authors.affiliation: From the Child Health Institute of New Jersey and Departments of Neuroscience and Cell Biology and.
authors.forename: Irene S
authors.initials: IS
authors.lastname: Pakos
authors.affiliation: From the Child Health Institute of New Jersey and Departments of Neuroscience and Cell Biology and.
authors.forename: Fanomezana M
authors.initials: FM
authors.lastname: Ranaivoson
authors.affiliation: From the Child Health Institute of New Jersey and Departments of Neuroscience and Cell Biology and.
authors.forename: Sventja
authors.initials: S
authors.lastname: von Daake
authors.affiliation: the Department of Biochemistry, The University of Texas Health Science Center, San Antonio, Texas 78229.
authors.forename: Borries
authors.initials: B
authors.lastname: Demeler
authors.affiliation: the Department of Biology and Biotechnologies "Charles Darwin" and Pasteur Institute-Cenci Bolognetti Foundation, Sapienza University of Rome, Rome, Italy 00185.
authors.forename: Antonella
authors.initials: A
authors.lastname: De Jaco
authors.affiliation: the National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, California 92093, and.
authors.forename: Guy
authors.initials: G
authors.lastname: Perkins
authors.affiliation: the National Center for Microscopy and Imaging Research, University of California San Diego, La Jolla, California 92093, and.
authors.forename: Mark H
authors.initials: MH
authors.lastname: Ellisman
authors.affiliation: the School of Molecular Bioscience, University of Sydney, New South Wales 2006, Australia,; the Department of Chemistry, University of Utah, Salt Lake City, Utah 84112.
authors.forename: Jill
authors.initials: J
authors.lastname: Trewhella
authors.affiliation: From the Child Health Institute of New Jersey and Departments of Neuroscience and Cell Biology and; Pediatrics, Robert Wood Johnson Medical School, Rutgers University, New Brunswick, New Jersey 08901,. Electronic address: comoleda@rwjms.rutgers.edu.
authors.forename: Davide
authors.initials: D
authors.lastname: Comoletti
mesh_terms: D000818:Animals; D002478:Cells, Cultured; D058967:Contactin 1 / Q000378:metabolism*; D057809:HEK293 Cells; D006624:Hippocampus / Q000166:cytology / Q000378:metabolism; D006801:Humans; D008565:Membrane Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D008810:Mice, Inbred C57BL; D008958:Models, Molecular; D009419:Nerve Tissue Proteins / Q000737:chemistry* / Q000378:metabolism* / Q000648:ultrastructure; D060066:Protein Interaction Maps; D017434:Protein Structure, Tertiary; D053838:Scattering, Small Angle; D014961:X-Ray Diffraction
chemical_list: C548669:CNTN1 protein, human; C403049:CNTNAP2 protein, human; D058967:Contactin 1; D008565:Membrane Proteins; D009419:Nerve Tissue Proteins
keywords: analytical ultracentrifugation; ligand-binding protein; molecular cell biology; protein structure; small-angle x-ray scattering (SAXS)