title: Peptides derived from human galectin-3 N-terminal tail interact with its carbohydrate recognition domain in a phosphorylation-dependent manner.
abstract: Galectin-3 (Gal-3) is a multi-functional effector protein that functions in the cytoplasm and the nucleus, as well as extracellularly following non-classical secretion. Structurally, Gal-3 is unique among galectins with its carbohydrate recognition domain (CRD) attached to a rather long N-terminal tail composed mostly of collagen-like repeats (nine in the human protein) and terminating in a short non-collagenous terminal peptide sequence unique in this lectin family and not yet fully explored. Although several Ser and Tyr sites within the N-terminal tail can be phosphorylated, the physiological significance of this post-translational modification remains unclear. Here, we used a series of synthetic (phospho)peptides derived from the tail to assess phosphorylation-mediated interactions with (15)N-labeled Gal-3 CRD. HSQC-derived chemical shift perturbations revealed selective interactions at the backface of the CRD that were attenuated by phosphorylation of Tyr 107 and Tyr 118, while phosphorylation of Ser 6 and Ser 12 was essential. Controls with sequence scrambling underscored inherent specificity. Our studies shed light on how phosphorylation of the N-terminal tail may impact on Gal-3 function and prompt further studies using phosphorylated full-length protein.
authors.affiliation: Chemical and Physical Biology Department, Centro de Investigaciones Biológicas, CSIC, 28040 Madrid, Spain.
authors.forename: M Álvaro
authors.initials: MÁ
authors.lastname: Berbís
authors.affiliation: Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians University, 80539 Munich, Germany.
authors.forename: Sabine
authors.initials: S
authors.lastname: André
authors.affiliation: Chemical and Physical Biology Department, Centro de Investigaciones Biológicas, CSIC, 28040 Madrid, Spain.
authors.forename: F Javier
authors.initials: FJ
authors.lastname: Cañada
authors.affiliation: Central Peptide Synthesis Unit, German Cancer Research Center, 69120 Heidelberg, Germany.
authors.forename: Rüdiger
authors.initials: R
authors.lastname: Pipkorn
authors.affiliation: Department of Biochemistry, CARIM, University of Maastricht, Maastricht, The Netherlands; Department of Biochemistry, Molecular Biology and Biophysics, University of Minnesota, Minneapolis, MN 55455, USA.
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: Kevin H
authors.initials: KH
authors.lastname: Mayo
authors.affiliation: Biomolecular Interactions, German Cancer Research Center, 69120 Heidelberg, Germany.
authors.forename: Dieter
authors.initials: D
authors.lastname: Kübler
authors.affiliation: Institute of Physiological Chemistry, Faculty of Veterinary Medicine, Ludwig-Maximilians University, 80539 Munich, Germany.
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Gabius
authors.affiliation: Chemical and Physical Biology Department, Centro de Investigaciones Biológicas, CSIC, 28040 Madrid, Spain. Electronic address: jjbarbero@cib.csic.es.
authors.forename: Jesús
authors.initials: J
authors.lastname: Jiménez-Barbero
mesh_terms: D000595:Amino Acid Sequence; D002241:Carbohydrates / Q000737:chemistry; D037502:Galectin 3 / Q000737:chemistry / Q000235:genetics / Q000378:metabolism*; D006801:Humans; D008969:Molecular Sequence Data; D010455:Peptides / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D010766:Phosphorylation; D017434:Protein Structure, Tertiary; D011994:Recombinant Proteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D014443:Tyrosine / Q000737:chemistry / Q000378:metabolism
chemical_list: D002241:Carbohydrates; D037502:Galectin 3; D010455:Peptides; D011994:Recombinant Proteins; D014443:Tyrosine
keywords: Agglutinin; CRD; Collagen; Gal-3; HSQC; Lectin; NMR; Phosphopeptide; Phosphorylation; carbohydrate recognition domain; galectin-3; heteronuclear single-quantum coherence; nuclear magnetic resonance