title: Fine-tuning of prototype chicken galectins: structure of CG-2 and structure-activity correlations.
abstract: The comparatively small number of members of the family of adhesion/growth-regulatory galectins in chicken predestines this system as an attractive model to study the divergence of these lectins after gene duplication. Expression profiling of the three homodimeric (prototype) chicken galectins (CG-1A, CG-1B and CG-2) has raised evidence of distinct functionalities, explaining the interest in a detailed crystallographic analysis of CG-2. As revealed here, marked differences are found in the ligand-binding site and in the contact pattern within the homodimer interface, underlying a characteristic orientation of the two subunits. Notably, a distinctive trimer of dimers that is unique in all galectin crystal structures reported to date forms the core unit of the crystallographic assembly. Combination with spectroscopic and thermodynamic measurements, and comparisons with CG-1A and CG-1B, identify differential changes in the circular-dichroism spectra in the presence of lactose, reflecting the far-reaching impact of the ligand on hydrodynamic behaviour, and inter-galectin differences in both the entropy and the enthalpy of binding. This structural information is a salient step to complete the analysis of the full set of galectins from this model organism.
authors.affiliation: Departamento de Biología Físico-Química, Centro de Investigaciones Biológicas - CSIC, Ramiro de Maeztu 9, 28040 Madrid, Spain.
authors.forename: Federico M
authors.initials: FM
authors.lastname: Ruiz
authors.forename: Israel S
authors.initials: IS
authors.lastname: Fernández
authors.forename: Lara
authors.initials: L
authors.lastname: López-Merino
authors.forename: Laura
authors.initials: L
authors.lastname: Lagartera
authors.forename: Herbert
authors.initials: H
authors.lastname: Kaltner
authors.forename: Margarita
authors.initials: M
authors.lastname: Menéndez
authors.forename: Sabine
authors.initials: S
authors.lastname: André
authors.forename: Dolores
authors.initials: D
authors.lastname: Solís
authors.forename: Hans Joachim
authors.initials: HJ
authors.lastname: Gabius
authors.forename: Antonio
authors.initials: A
authors.lastname: Romero
mesh_terms: D000818:Animals; D002645:Chickens; D018360:Crystallography, X-Ray; D037483:Galectin 1 / Q000737:chemistry; D037501:Galectin 2 / Q000737:chemistry* / Q000378:metabolism; D037161:Galectins / Q000737:chemistry* / Q000378:metabolism; D006801:Humans; D008024:Ligands; D008956:Models, Chemical; D011485:Protein Binding; D055503:Protein Multimerization; D016415:Sequence Alignment; D013329:Structure-Activity Relationship
chemical_list: D037483:Galectin 1; D037501:Galectin 2; D037161:Galectins; C445499:LGALS1 protein, human; D008024:Ligands
keywords: homology; lectins; oligomerization; phylogeny; β-sandwich