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Permanent URL to this publication: http://dx.doi.org/10.5167/uzh-62959

Schubert, Mario; Bleuler-Martinez, Silvia; Butschi, Alex; Wälti, Martin A; Egloff, Pascal; Stutz, Katrin; Yan, Shi; Wilson, Iain B H; Hengartner, Michael O; Aebi, Markus; Allain, Frédéric H-T; Künzler, Markus (2012). Plasticity of the β-Trefoil Protein Fold in the Recognition and Control of Invertebrate Predators and Parasites by a Fungal Defence System. PLoS Pathogens, 8(5):e1002706.

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Abstract

Discrimination between self and non-self is a prerequisite for any defence mechanism; in innate defence, this discrimination is often mediated by lectins recognizing non-self carbohydrate structures and so relies on an arsenal of host lectins with different specificities towards target organism carbohydrate structures. Recently, cytoplasmic lectins isolated from fungal fruiting bodies have been shown to play a role in the defence of multicellular fungi against predators and parasites. Here, we present a novel fruiting body lectin, CCL2, from the ink cap mushroom Coprinopsis cinerea. We demonstrate the toxicity of the lectin towards Caenorhabditis elegans and Drosophila melanogaster and present its NMR solution structure in complex with the trisaccharide, GlcNAcβ1,4[Fucα1,3]GlcNAc, to which it binds with high specificity and affinity in vitro. The structure reveals that the monomeric CCL2 adopts a β-trefoil fold and recognizes the trisaccharide by a single, topologically novel carbohydrate-binding site. Site-directed mutagenesis of CCL2 and identification of C. elegans mutants resistant to this lectin show that its nematotoxicity is mediated by binding to α1,3-fucosylated N-glycan core structures of nematode glycoproteins; feeding with fluorescently labeled CCL2 demonstrates that these target glycoproteins localize to the C. elegans intestine. Since the identified glycoepitope is characteristic for invertebrates but absent from fungi, our data show that the defence function of fruiting body lectins is based on the specific recognition of non-self carbohydrate structures. The trisaccharide specifically recognized by CCL2 is a key carbohydrate determinant of pollen and insect venom allergens implying this particular glycoepitope is targeted by both fungal defence and mammalian immune systems. In summary, our results demonstrate how the plasticity of a common protein fold can contribute to the recognition and control of antagonists by an innate defence mechanism, whereby the monovalency of the lectin for its ligand implies a novel mechanism of lectin-mediated toxicity.

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute of Molecular Life Sciences
DDC:570 Life sciences; biology
Language:English
Date:17 May 2012
Deposited On:20 Jun 2012 15:19
Last Modified:08 Dec 2013 01:10
Publisher:Public Library of Science
ISSN:1553-7366
Publisher DOI:10.1371/journal.ppat.1002706
PubMed ID:22615566
Citations:Web of Science®. Times Cited: 8
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Scopus®. Citation Count: 9

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