title: Solving the phase problem for carbohydrate-binding proteins using selenium derivatives of their ligands: a case study involving the bacterial F17-G adhesin.
abstract: The Escherichia coli adhesin F17-G is a carbohydrate-binding protein that allows the bacterium to attach to the intestinal epithelium of young ruminants. The structure of the 17 kDa lectin domain of F17-G was determined using the anomalous dispersion signal of a selenium-containing analogue of the monosaccharide ligand N-acetyl-d-glucosamine in which the anomeric oxygen was replaced by an Se atom. A three-wavelength MAD data set yielded good experimental phases to 2.6 A resolution. The structure was refined to 1.75 A resolution and was used to solve the structures of the ligand-free protein and the F17-G-N-acetyl-d-glucosamine complex. This selenium-carbohydrate phasing method could be of general use for determining the structures of carbohydrate-binding proteins.
authors.affiliation: Department of Ultrastructure, Vrije Universiteit Brussel, Vlaams Interuniversitair Instituut voor Biotechnologie (VIB), Pleinlaan 2, 1050 Brussels, Belgium.
authors.forename: Lieven
authors.initials: L
authors.lastname: Buts
authors.forename: Remy
authors.initials: R
authors.lastname: Loris
authors.forename: Erwin
authors.initials: E
authors.lastname: De Genst
authors.forename: Stefan
authors.initials: S
authors.lastname: Oscarson
authors.forename: Martina
authors.initials: M
authors.lastname: Lahmann
authors.forename: Joris
authors.initials: J
authors.lastname: Messens
authors.forename: Elke
authors.initials: E
authors.lastname: Brosens
authors.forename: Lode
authors.initials: L
authors.lastname: Wyns
authors.forename: Henri
authors.initials: H
authors.lastname: De Greve
authors.forename: Julie
authors.initials: J
authors.lastname: Bouckaert
mesh_terms: D000117:Acetylglucosamine / Q000737:chemistry; D018829:Adhesins, Bacterial; D002352:Carrier Proteins / Q000737:chemistry* / Q000378:metabolism*; D003460:Crystallization; D029968:Escherichia coli Proteins / Q000737:chemistry*; D006860:Hydrogen Bonding; D007202:Indicators and Reagents; D008024:Ligands; D008958:Models, Molecular; D011485:Protein Binding; D011956:Receptors, Cell Surface; D018036:Selenium Compounds / Q000737:chemistry*
chemical_list: D018829:Adhesins, Bacterial; D002352:Carrier Proteins; D029968:Escherichia coli Proteins; C480724:F17-G adhesin protein, E coli; D007202:Indicators and Reagents; D008024:Ligands; D011956:Receptors, Cell Surface; D018036:Selenium Compounds; C055213:saccharide-binding proteins; D000117:Acetylglucosamine