title: Intra- and intermolecular interactions of human galectin-3: assessment by full-assignment-based NMR.
abstract: Galectin-3 is an adhesion/growth-regulatory protein with a modular design comprising an N-terminal tail (NT, residues 1-111) and the conserved carbohydrate recognition domain (CRD, residues 112-250). The chimera-type galectin interacts with both glycan and peptide motifs. Complete (13)C/(15)N-assignment of the human protein makes NMR-based analysis of its structure beyond the CRD possible. Using two synthetic NT polypeptides covering residues 1-50 and 51-107, evidence for transient secondary structure was found with helical conformation from residues 5 to 15 as well as proline-mediated, multi-turn structure from residues 18 to 32 and around PGAYP repeats. Intramolecular interactions occur between the CRD F-face (the 5-stranded β-sheet behind the canonical carbohydrate-binding 6-stranded β-sheet of the S-face) and NT in full-length galectin-3, with the sequence P(23)GAW(26)…P(37)GASYPGAY(45) defining the primary binding epitope within the NT. Work with designed peptides indicates that the PGAX motif is crucial for self-interactions between NT/CRD. Phosphorylation at position Ser6 (and Ser12) (a physiological modification) and the influence of ligand binding have minimal effect on this interaction. Finally, galectin-3 molecules can interact weakly with each other via the F-faces of their CRDs, an interaction that appears to be assisted by their NTs. Overall, our results add insight to defining binding sites on galectin-3 beyond the canonical contact area for β-galactosides.
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.|Department of Biochemistry and CARIM, Maastricht University, Maastricht, The Netherlands.
authors.forename: Hans
authors.initials: H
authors.lastname: Ippel
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Michelle C
authors.initials: MC
authors.lastname: Miller
authors.affiliation: Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians-University Munich, 80539 Munich, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: Vértesy
authors.affiliation: School of Life Science, Northeast Normal University, 130024 Changchun, People's Republic of China.
authors.forename: Yi
authors.initials: Y
authors.lastname: Zheng
authors.affiliation: Chemical and Physical Biology, Centro de Investigaciones Biológicas, CSIC, 28040 Madrid, Spain.
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Cañada
authors.affiliation: Department of Biochemistry and CARIM, Maastricht University, Maastricht, The Netherlands.
authors.forename: Dennis
authors.initials: D
authors.lastname: Suylen
authors.affiliation: Department of Chemistry, International Christian University, Tokyo, Japan.
authors.forename: Kimiko
authors.initials: K
authors.lastname: Umemoto
authors.affiliation: Center for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Cecilia
authors.initials: C
authors.lastname: Romanò
authors.affiliation: Department of Biochemistry and CARIM, Maastricht University, Maastricht, The Netherlands.
authors.forename: Tilman
authors.initials: T
authors.lastname: Hackeng
authors.affiliation: School of Life Science, Northeast Normal University, 130024 Changchun, People's Republic of China.
authors.forename: Guihua
authors.initials: G
authors.lastname: Tai
authors.affiliation: Department of Laboratory Medicine, Microbiology, Immunology, Glycobiology Section, 22362 Lund, Sweden.
authors.forename: Hakon
authors.initials: H
authors.lastname: Leffler
authors.affiliation: Institute of Pathology, Applied Tumor Biology, Ruprecht-Karls-University, 69120 Heidelberg, Germany.
authors.forename: Jürgen
authors.initials: J
authors.lastname: Kopitz
authors.affiliation: Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians-University Munich, 80539 Munich, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: André
authors.affiliation: Mechanismen Biomolekularer Interaktionen, Deutsches Krebsforschungszentrum, 69120 Heidelberg, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Kübler
authors.affiliation: CIC bioGUNE, Bizkaia Technological Park, 48160 Derio, Spain.|Ikerbasque, Basque Science Foundation, 28009 Bilbao, Spain.
authors.forename: Jesús
authors.initials: J
authors.lastname: Jiménez-Barbero
authors.affiliation: Center for Synthesis and Chemical Biology, University College Dublin, Belfield, Dublin 4, Ireland.
authors.forename: Stefan
authors.initials: S
authors.lastname: Oscarson
authors.affiliation: Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians-University Munich, 80539 Munich, Germany.
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Gabius
authors.affiliation: Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
authors.forename: Kevin H
authors.initials: KH
authors.lastname: Mayo
mesh_terms: D000595:Amino Acid Sequence; D001665:Binding Sites; D001798:Blood Proteins; D002247:Carbon Isotopes / Q000737:chemistry; D003001:Cloning, Molecular; D004926:Escherichia coli / Q000235:genetics / Q000378:metabolism; D037502:Galectin 3 / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D037161:Galectins; D015870:Gene Expression; D005822:Genetic Vectors / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008958:Models, Molecular; D009587:Nitrogen Isotopes / Q000737:chemistry; D019906:Nuclear Magnetic Resonance, Biomolecular; D010455:Peptides / Q000138:chemical synthesis / Q000737:chemistry* / Q000378:metabolism; D010766:Phosphorylation; D011485:Protein Binding; D000072756:Protein Conformation, alpha-Helical; D000072757:Protein Conformation, beta-Strand; D054730:Protein Interaction Domains and Motifs; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D016415:Sequence Alignment
chemical_list: D001798:Blood Proteins; D002247:Carbon Isotopes; D037502:Galectin 3; D037161:Galectins; C428445:LGALS3 protein, human; D009587:Nitrogen Isotopes; D010455:Peptides; D011994:Recombinant Proteins
keywords: adhesion; apoptosis; lectin; phosphorylation; self-association