PDBsum entry 1jot

Lectin

PDB id: 1jot

Contents

Protein chains

133 a.a. *

16 a.a. *

Ligands

A2G-GAL

Waters ×91

* Residue conservation analysis

PDB id:

1jot

Name:

Lectin

Title:

Structure of the lectin mpa complexed with t-antigen disaccharide

Structure:

Agglutinin. Chain: a. Agglutinin. Chain: b

Source:

Maclura pomifera. Osage orange. Organism_taxid: 3496. Organ: seeds. Other_details: from the seeds of the moraceae plant family. Other_details: from the seeds of the moraceae plant family

Biol. unit:

Octamer (from PQS)

Resolution:

2.20Å R-factor: 0.172 R-free: 0.222

Authors:

X.Lee,A.Thompson,Z.Zhang,T.-T.Hoa,J.Biesterfeldt,C.Ogata,L.Xu, R.A.Z.Johnston,N.M.Young

Key ref:

X.Lee et al. (1998). Structure of the complex of Maclura pomifera agglutinin and the T-antigen disaccharide, Galbeta1,3GalNAc. J Biol Chem, 273, 6312-6318. PubMed id: 9497359 DOI: 10.1074/jbc.273.11.6312

Date:

05-Dec-97 Release date: 30-Dec-98

Protein chain

P18674  (LECA_MACPO) -  Agglutinin alpha chain from Maclura pomifera

Seq: 133 a.a.

Struc: 133 a.a.

Protein chain

P18676  (LECB2_MACPO) -  Agglutinin beta-2 chain from Maclura pomifera

Seq: 20 a.a.

Struc: 16 a.a.

Enzyme reactions

• Enzyme class: Chains A, B: E.C.?

DOI no: 10.1074/jbc.273.11.6312

J Biol Chem 273:6312-6318 (1998)

PubMed id: 9497359

Structure of the complex of Maclura pomifera agglutinin and the T-antigen disaccharide, Galbeta1,3GalNAc.

X.Lee, A.Thompson, Z.Zhang, H.Ton-that, J.Biesterfeldt, C.Ogata, L.Xu, R.A.Johnston, N.M.Young.

ABSTRACT

Maclura pomifera agglutinin is a tetrameric plant seed lectin with high affinity for the tumor-associated T-antigen disaccharide, Galbeta1,3GalNAcalpha, and hence for many O-linked glycopeptide structures. Unlike members of most lectin families, it lacks both metal ions and Cys residues. The structure of its complex with Galbeta1,3GalNAc was determined to 2.2 by first using multiwavelength anomalous diffraction with a lead derivative of the native protein, and then using molecular replacement with the unrefined structure as a model to solve the structure of the complex. The subunits share the beta-prism architecture and three-fold pseudo-symmetry of the related lectin jacalin, with the 21-residue beta-chains in the center of the tetramer. Interactions with the GalNAc predominate in the binding of the disaccharide. It forms a network of H-bonds with only one side chain, from an Asp residue, the amino group of the N-terminal Gly of the alpha-chain, and peptide backbone atoms of two aromatic residues. The Gal moiety does not H-bond directly with residues in the same monomer, i.e. there is no true subsite for it, but there are interactions through two water molecules. In the crystal, it interacts with residues in the binding site of an adjacent tetramer. The minimum energy conformation expected for the disaccharide is retained, despite its mediating the tetramer-tetramer interactions in the crystal packing. The resulting lattice is comparable to those seen for complexes of other lectins with branched glycopeptides.

Selected figure(s)

Figure 3.
Fig. 3. Backbone structure of the tetramer with the bound ligand. The Greek key subdomains of each monomer are shown in red, green, and purple with the -chain in blue (see Fig. 4). This figure and Figs. 4 and 5 were prepared with MOLSCRIPT (21) and^ RASTER 3D (22).

Figure 6.
Fig. 6. Hydrogen-bonding scheme for the MPA-disaccharide complex. The two charged groups of Gly-1 and Asp-125 form most of^ the H-bonds, to the GalNAc. The remaining H-bonds are from backbone^ atoms plus two water molecules, one of which forms the only H-bond^ to the Gal.

The above figures are reprinted by permission from the ASBMB: J Biol Chem (1998, 273, 6312-6318) copyright 1998.

Figures were selected by an automated process.