4USP

X-ray structure of the dimeric CCL2 lectin in native form

Summary for 4USP

• Entry DOI: 10.2210/pdb4usp/pdb
• Related: 4USO 4UT5
• Descriptor: CCL2 LECTIN, CHLORIDE ION, PHOSPHATE ION, ... (4 entities in total)
• Functional Keywords: sugar binding protein, lectin, fungal
• Biological source: COPRINOPSIS CINEREA (INK CAP FUNGUS)
• Total number of polymer chains: 2
• Total formula weight: 33338.99

Authors

Bleuler-Martinez, S.,Varrot, A.,Schubert, M.,Stutz, M.,Sieber, R.,Hengartner, M.,Aebi, M.,Kunzler, M. (deposition date: 2014-07-11, release date: 2015-07-22, Last modification date: 2024-01-10)

Primary citation

Bleuler-Martinez, S.,Stutz, K.,Sieber, R.,Collot, M.,Mallet, J.M.,Hengartner, M.,Schubert, M.,Varrot, A.,Kunzler, M.
Dimerization of the fungal defense lectin CCL2 is essential for its toxicity against nematodes.
Glycobiology, 27:486-500, 2017

PubMed Abstract: Lectins are used as defense effector proteins against predators, parasites and pathogens by animal, plant and fungal innate defense systems. These proteins bind to specific glycoepitopes on the cell surfaces and thereby interfere with the proper cellular functions of the various antagonists. The exact cellular toxicity mechanism is in many cases unclear. Lectin CCL2 of the mushroom Coprinopsis cinerea was previously shown to be toxic for Caenorhabditis elegans and Drosophila melanogaster. This toxicity is dependent on a single, high-affinity binding site for the trisaccharide GlcNAc(Fucα1,3)β1,4GlcNAc, which is a hallmark of nematode and insect N-glycan cores. The carbohydrate-binding site is located at an unusual position on the protein surface when compared to other β-trefoil lectins. Here, we show that CCL2 forms a compact dimer in solution and in crystals. Substitution of two amino acid residues at the dimer interface, R18A and F133A, interfered with dimerization of CCL2 and reduced toxicity but left carbohydrate-binding unaffected. These results, together with the positioning of the two carbohydrate-binding sites on the surface of the protein dimer, suggest that crosslinking of N-glycoproteins on the surface of intestinal cells of invertebrates is a crucial step in the mechanism of CCL2-mediated toxicity. Comparisons of the number and positioning of carbohydrate-binding sites among different dimerizing fungal β-trefoil lectins revealed a considerable variability in the carbohydrate-binding patterns of these proteins, which are likely to correlate with their respective functions.

PubMed: 27980000
DOI: 10.1093/glycob/cww113

Experimental method

X-RAY DIFFRACTION (2.25 Å)