Solving the phase problem for carbohydrate-binding proteins using selenium derivatives of their ligands: a case study involving the bacterial F17-G adhesin.
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.
Buts
Lieven
L
Department of Ultrastructure, Vrije Universiteit Brussel, Vlaams Interuniversitair Instituut voor Biotechnologie (VIB), Pleinlaan 2, 1050 Brussels, Belgium.
Loris
Remy
R
De Genst
Erwin
E
Oscarson
Stefan
S
Lahmann
Martina
M
Messens
Joris
J
Brosens
Elke
E
Wyns
Lode
L
De Greve
Henri
H
Bouckaert
Julie
J
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*
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