1ulm
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(New page: 200px<br /><applet load="1ulm" size="450" color="white" frame="true" align="right" spinBox="true" caption="1ulm, resolution 1.80Å" /> '''Crystal Structure of...)
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Revision as of 02:06, 21 November 2007
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Crystal Structure of Pokeweed Lectin-D2 complexed with tri-N-acetylchitotriose
Overview
The roots of pokeweed (Phytolacca americana) are known to contain the, lectins designated PL-A, PL-B, PL-C, PL-D1, and PL-D2. Of these lectins, the crystal structures of two PLs, the ligand-free PL-C and the complex of, PL-D2 with tri-N-acetylchitotriose, have been determined at 1.8A, resolution. The polypeptide chains of PL-C and PL-D2 form three and two, repetitive chitin-binding domains, respectively. In the crystal structure, of the PL-D2 complex, one trisaccharide molecule is shared mainly between, two neighboring molecules related to each other by a crystallographic, 2(1)-screw axis, and infinite helical chains of complexed molecules are, generated by the sharing of ligand molecules. The crystal structure of, PL-C reveals that the molecule is a dimer of two identical subunits, whose, polypeptide chains are located in a head-to-tail fashion by a molecular, 2-fold axis. Three putative carbohydrate-binding sites in each subunit are, located in the dimer interface. The dimerization of PL-C is performed, through the hydrophobic interactions between the carbohydrate-binding, sites of the opposite domains in the dimer, leading to a distinct, dimerization mode from that of wheat-germ agglutinin. Three aromatic, residues in each carbohydrate-binding site of PL-C are involved in the, dimerization. These residues correspond to the residues that interact, mainly with the trisaccharide in the PL-D2 complex and appear to mimic the, saccharide residues in the complex. Consequently, the present structure of, the PL-C dimer has no room for accommodating carbohydrate. The quaternary, structure of PL-C formed through these putative carbohydrate-binding, residues may lead to the lack of hemagglutinating activity.
About this Structure
1ULM is a Protein complex structure of sequences from Phytolacca americana. Full crystallographic information is available from OCA.
Reference
Similarity between protein-protein and protein-carbohydrate interactions, revealed by two crystal structures of lectins from the roots of pokeweed., Hayashida M, Fujii T, Hamasu M, Ishiguro M, Hata Y, J Mol Biol. 2003 Nov 28;334(3):551-65. PMID:14623194
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