PDBsum entry 1j4t

Plant protein

PDB id: 1j4t

Contents

Protein chains

(+ 2 more) 149 a.a. *

Waters ×874

* Residue conservation analysis

PDB id:

1j4t

Name:

Plant protein

Title:

Structure of artocarpin: a lectin with mannose specificity (form 2)

Structure:

Artocarpin. Chain: a, b, c, d, e, f, g, h

Source:

Artocarpus integer. Organism_taxid: 3490. Other_details: seeds

Biol. unit:

Tetramer (from PQS)

Resolution:

2.40Å R-factor: 0.191 R-free: 0.258

Authors:

J.V.Pratap,A.A.Jeyaprakash,P.G.Rani,K.Sekar,A.Surolia,M.Vijayan

Key ref:

J.V.Pratap et al. (2002). Crystal structures of artocarpin, a Moraceae lectin with mannose specificity, and its complex with methyl-alpha-D-mannose: implications to the generation of carbohydrate specificity. J Mol Biol, 317, 237-247. PubMed id: 11902840 DOI: 10.1006/jmbi.2001.5432

Date:

30-Oct-01 Release date: 27-Mar-02

Protein chains

Q7M1T4  (Q7M1T4_ARTIN) -  Mannose-specific lectin KM+ from Artocarpus integer

Seq: 149 a.a.

Struc: 149 a.a.*

* PDB and UniProt seqs differ at 8 residue positions (black crosses)

DOI no: 10.1006/jmbi.2001.5432

J Mol Biol 317:237-247 (2002)

PubMed id: 11902840

Crystal structures of artocarpin, a Moraceae lectin with mannose specificity, and its complex with methyl-alpha-D-mannose: implications to the generation of carbohydrate specificity.

J.V.Pratap, A.A.Jeyaprakash, P.G.Rani, K.Sekar, A.Surolia, M.Vijayan.

ABSTRACT

The seeds of jack fruit (Artocarpus integrifolia) contain two tetrameric lectins, jacalin and artocarpin. Jacalin was the first lectin found to exhibit the beta-prism I fold, which is characteristic of the Moraceae plant lectin family. Jacalin contains two polypeptide chains produced by a post-translational proteolysis which has been shown to be crucial for generating its specificity for galactose. Artocarpin is a single chain protein with considerable sequence similarity with jacalin. It, however, exhibits many properties different from those of jacalin. In particular, it is specific to mannose. The structures of two crystal forms, form I and form II, of the native lectin have been determined at 2.4 and 2.5 A resolution, respectively. The structure of the lectin complexed with methyl-alpha-mannose, has also been determined at 2.9 A resolution. The structure is similar to jacalin, although differences exist in details. The crystal structures and detailed modelling studies indicate that the following differences between the carbohydrate binding sites of artocarpin and jacalin are responsible for the difference in the specificities of the two lectins. Firstly, artocarpin does not contain, unlike jacalin, an N terminus generated by post-translational proteolysis. Secondly, there is no aromatic residue in the binding site of artocarpin whereas there are four in that of jacalin. A comparison with similar lectins of known structures or sequences, suggests that, in general, stacking interactions with aromatic residues are important for the binding of galactose while such interactions are usually absent in the carbohydrate binding sites of mannose-specific lectins with the beta-prism I fold.

Selected figure(s)

Figure 1.
Figure 1. Structure of artocarpin. (a) Schematic representation showing hydrogen bonds. (b) The subunit with the three Greek keys coloured differently. (c) Quaternary structure with the four subunits coloured differently. Figures 1(b) 4 were prepared using BOBSCRIPT. [44]

Figure 3.
Figure 3. (a) Stereo view of the sugar molecule in the A subunit with the 2|F[o]| -|F[c]| map contoured at 1s and (b) hydrogen bonds observed between the protein and sugar.

The above figures are reprinted by permission from Elsevier: J Mol Biol (2002, 317, 237-247) copyright 2002.

Figures were selected by an automated process.