title: Detection of ligand- and solvent-induced shape alterations of cell-growth-regulatory human lectin galectin-1 in solution by small angle neutron and x-ray scattering.
abstract: The bioactivity of galectin-1 in cell growth regulation and adhesion prompted us to answer the questions whether ligand presence and a shift to an aprotic solvent typical for bioaffinity chromatography might alter the shape of the homodimeric human lectin in solution. We used small angle neutron and synchrotron x-ray scattering studies for this purpose. Upon ligand accommodation, the radius of gyration of human galectin-1 decreased from 19.1 +/- 0.1 A in the absence of ligand to 18.2 +/- 0.1 A. In the aprotic solvent dimethyl sulfoxide, which did not impair binding capacity, galectin-1 formed dimers of a dimer, yielding tetramers with a cylindrical shape. Intriguingly, no dissociation into subunits occurred. In parallel, NMR monitoring was performed. The spectral resolution was in accord with these data. In contrast to the properties of the human protein, a nonhomologous agglutinin from mistletoe sharing galactose specificity was subject to a reduction in the radius of gyration from approximately 62 A in water to 48.7 A in dimethyl sulfoxide. Evidently, the solvent caused opposite responses in the two tested galactoside-binding lectins with different folding patterns. We have hereby proven that ligand presence and an aprotic solvent significantly affect the shape of galectin-1 in solution.
authors.affiliation: Institute for Coastal Research, Physical and Chemical Analysis, Geesthacht, Germany.
authors.forename: Lizhong
authors.initials: L
authors.lastname: He
authors.forename: Sabine
authors.initials: S
authors.lastname: André
authors.forename: Hans-Christian
authors.initials: HC
authors.lastname: Siebert
authors.forename: Heike
authors.initials: H
authors.lastname: Helmholz
authors.forename: Bernd
authors.initials: B
authors.lastname: Niemeyer
authors.forename: Hans-Joachim
authors.initials: HJ
authors.lastname: Gabius
mesh_terms: D003198:Computer Simulation; D004058:Diffusion; D019281:Dimerization; D004121:Dimethyl Sulfoxide / Q000737:chemistry*; D037483:Galectin 1 / Q000737:chemistry*; D006801:Humans; D008024:Ligands; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D033363:Neutron Diffraction / Q000379:methods*; D011485:Protein Binding; D011487:Protein Conformation; D011489:Protein Denaturation; D017510:Protein Folding; D012997:Solvents / Q000737:chemistry; D013696:Temperature; D014867:Water / Q000737:chemistry*; D014961:X-Ray Diffraction / Q000379:methods*
chemical_list: D037483:Galectin 1; D008024:Ligands; D012997:Solvents; D014867:Water; D004121:Dimethyl Sulfoxide