PDBsum entry 1toq

Sugar binding protein

PDB id: 1toq

Contents

Protein chains

133 a.a. *

15 a.a. *

Ligands

AMG ×4

Waters ×110

* Residue conservation analysis

PDB id:

1toq

Name:

Sugar binding protein

Title:

Crystal structure of a galactose specific lectin from artocarpus hirsuta in complex with methyl-a-d-galactose

Structure:

Agglutinin alpha chain. Chain: a, c, e, g. Agglutinin beta chain. Chain: b, d, f, h. Engineered: yes

Source:

Artocarpus hirsutus. Organism_taxid: 291940. Other_details: seeds. Synthetic: yes. Other_details: chemically synthesized

Biol. unit:

Octamer (from PQS)

Resolution:

2.50Å R-factor: 0.197 R-free: 0.235

Authors:

K.N.Rao,C.G.Suresh,U.V.Katre,S.M.Gaikwad,M.I.Khan

Key ref:

K.N.Rao et al. (2004). Two orthorhombic crystal structures of a galactose-specific lectin from Artocarpus hirsuta in complex with methyl-alpha-D-galactose. Acta Crystallogr D Biol Crystallogr, 60, 1404-1412. PubMed id: 15272163 DOI: 10.1107/S090744490401354X

Date:

15-Jun-04 Release date: 03-Aug-04

Protein chains

P18670  (LECA_ARTIN) -  Agglutinin alpha chain from Artocarpus integer

Seq: 133 a.a.

Struc: 133 a.a.*

Protein chains

P18673  (LECB3_ARTIN) -  Agglutinin beta-3 chain from Artocarpus integer

Seq: 20 a.a.

Struc: 15 a.a.*

* PDB and UniProt seqs differ at 5 residue positions (black crosses)

DOI no: 10.1107/S090744490401354X

Acta Crystallogr D Biol Crystallogr 60:1404-1412 (2004)

PubMed id: 15272163

Two orthorhombic crystal structures of a galactose-specific lectin from Artocarpus hirsuta in complex with methyl-alpha-D-galactose.

K.N.Rao, C.G.Suresh, U.V.Katre, S.M.Gaikwad, M.I.Khan.

ABSTRACT

Based on their carbohydrate specificity, the jacalin family of lectins can be divided into two groups: galactose-specific and mannose-specific. The former are cytoplasmic proteins, whereas the latter are localized in the storage vacuoles of cells. It has been proposed that the post-translational modification in some of the lectins that splits their polypeptide chains into two may be crucial for galactose specificity. The mannose-specific members of the family are single-chain proteins that lack the above modification. Although the galactose-specific and the mannose-specific jacalin-type lectins differ in their sequences, they share a common fold: the beta-prism I fold, which is characteristic of Moraceae plant lectins. Here, two crystal structures of a jacalin-related lectin from Artocarpus hirsuta, which is specific for galactose, in complex with methyl-alpha-D-galactose are reported. The lectin crystallized in two orthorhombic forms and one hexagonal form under similar conditions. The crystals had an unusually high solvent content. The structure was solved using the molecular-replacement method using the jacalin structure as a search model. The two orthorhombic forms were refined using data to 2.5 and 3.0 A resolution, respectively. The structures of the A. hirsuta lectin and jacalin are identical. In orthorhombic form I the crystal packing provides three different micro-environments for sugar binding in the same crystal. The observed difference in the specificity for oligosaccharides between the A. hirsuta lectin and jacalin could only be explained based on differences in the molecular associations in the packing and variation of the C-terminal length of the beta-chain. The observed insecticidal activity of A. hirsuta lectin may arise from its similar fold to domain II of the unrelated delta-endotoxin from Bacillus thuringiensis.

Selected figure(s)

Figure 1.
Figure 1 Schematic diagram showing the hydrogen bonds between main-chain atoms of three -sheets and the organization of the three Greek-key motifs in the subunit of A. hirsuta lectin. N1 and N2 and C1 and C2 are the N- and C-termini of the -chain and -chain, respectively. The numbering in the diagram corresponds to the residue numbering in the crystal structure.

Figure 4.
Figure 4 (a) The quaternary structure of A. hirsuta lectin, showing tetramer association. (b) The view of the tetramer that shows the tetrahedral positions of the sugar-binding sites with respect to the centre of the tetramer.

The above figures are reprinted by permission from the IUCr: Acta Crystallogr D Biol Crystallogr (2004, 60, 1404-1412) copyright 2004.

Figures were selected by an automated process.