PDBsum entry: 2uwg

Sugar-binding protein

PDB id: 2uwg

Contents

Protein chains

170 a.a. *

Ligands

GYU ×4

GOL ×2

Waters ×245

* Residue conservation analysis

PDB id:

2uwg

Name:

Sugar-binding protein

Title:

Crystal structure of wheat germ agglutinin isolectin 1 in complex with glycosylurethan

Structure:

Agglutinin isolectin 1. Chain: a, b. Fragment: residues 27-197. Synonym: wga1, isolectin a, heat germ agglutinin isolectin 1

Source:

Triticum aestivum. Bread wheat. Organism_taxid: 4565

Resolution:

1.60Å R-factor: 0.198 R-free: 0.232

Authors:

D.Schwefel,V.Wittmann,K.Diederichs,W.Welte

Key ref:

D.Schwefel et al. (2010). Structural basis of multivalent binding to wheat germ agglutinin. J Am Chem Soc, 132, 8704-8719. PubMed id: 20527753 DOI: 10.1021/ja101646k

Date:

21-Mar-07 Release date: 13-May-08

Protein chains

P10968  (AGI1_WHEAT) -  Agglutinin isolectin 1

Seq: 212 a.a.

Struc: 170 a.a.*

* PDB and UniProt seqs differ at 1 residue position (black cross)

 Gene Ontology (GO) functional annotation 

• Biological process: cell wall macromolecule catabolic process (2 terms)
• Biochemical function: sugar binding (3 terms)

DOI no: 10.1021/ja101646k

J Am Chem Soc 132:8704-8719 (2010)

PubMed id: 20527753

Structural basis of multivalent binding to wheat germ agglutinin.

D.Schwefel, C.Maierhofer, J.G.Beck, S.Seeberger, K.Diederichs, H.M.Möller, W.Welte, V.Wittmann.

ABSTRACT

The inhibition of carbohydrate-protein interactions by tailored multivalent ligands is a powerful strategy for the treatment of many human diseases. Crucial for the success of this approach is an understanding of the molecular mechanisms as to how a binding enhancement of a multivalent ligand is achieved. We have synthesized a series of multivalent N-acetylglucosamine (GlcNAc) derivatives and studied their interaction with the plant lectin wheat germ agglutinin (WGA) by an enzyme-linked lectin assay (ELLA) and X-ray crystallography. The solution conformation of one ligand was determined by NMR spectroscopy. Employing a GlcNAc carbamate motif with alpha-configuration and by systematic variation of the spacer length, we were able to identify divalent ligands with unprecedented high WGA binding potency. The best divalent ligand has an IC(50) value of 9.8 microM (ELLA) corresponding to a relative potency of 2350 (1170 on a valency-corrected basis, i.e., per mol sugar contained) compared to free GlcNAc. X-ray crystallography of the complex of WGA and the second best, closely related divalent ligand explains this activity. Four divalent molecules simultaneously bind to WGA with each ligand bridging adjacent binding sites. This shows for the first time that all eight sugar binding sites of the WGA dimer are simultaneously functional. We also report a tetravalent neoglycopeptide with an IC(50) value of 0.9 microM being 25,500 times higher than that of GlcNAc (6400 times per contained sugar) and the X-ray structure analysis of its complex with glutaraldehyde-cross-linked WGA. Comparison of the crystal structure and the solution NMR structure of the neoglycopeptide as well as results from the ELLA suggest that the conformation of the glycopeptide in solution is already preorganized in a way supporting multivalent binding to the protein. Our findings show that bridging adjacent protein binding sites by multivalent ligands is a valid strategy to find high-affinity protein ligands and that even subtle changes of the linker structure can have a significant impact on the binding affinity.