Download MendeleyBivalent carbohydrate binding is required for biological activity of Clitocybe nebularis lectin (CNL), the N,N'-diacetyllactosediamine (GalNAc beta 1-4GlcNAc, LacdiNAc)-specific lectin from basidiomycete C. nebularis
Pohleven, J., Renko, M., Magister, S., Smith, D.F., Kunzler, M., Strukelj, B., Turk, D., Kos, J., Sabotic, J.(2012) J Biological Chem 287: 10602-10612
- PubMed: 22298779
- DOI: https://doi.org/10.1074/jbc.M111.317263
- Primary Citation of Related Structures:
3NBC, 3NBD, 3NBE - PubMed Abstract:
Lectins are carbohydrate-binding proteins that exert their biological activity by binding to specific cell glycoreceptors. We have expressed CNL, a ricin B-like lectin from the basidiomycete Clitocybe nebularis in Escherichia coli. The recombinant lectin, rCNL, agglutinates human blood group A erythrocytes and is specific for the unique glycan N,N'-diacetyllactosediamine (GalNAcβ1-4GlcNAc, LacdiNAc) as demonstrated by glycan microarray analysis. We here describe the crystal structures of rCNL in complex with lactose and LacdiNAc, defining its interactions with the sugars. CNL is a homodimeric lectin, each of whose monomers consist of a single ricin B lectin domain with its β-trefoil fold and one carbohydrate-binding site. To study the mode of CNL action, a nonsugar-binding mutant and nondimerizing monovalent CNL mutants that retain carbohydrate-binding activity were prepared. rCNL and the mutants were examined for their biological activities against Jurkat human leukemic T cells and the hypersensitive nematode Caenorhabditis elegans mutant strain pmk-1. rCNL was toxic against both, although the mutants were inactive. Thus, the bivalent carbohydrate-binding property of homodimeric CNL is essential for its activity, providing one of the rare pieces of evidence that certain activities of lectins are associated with their multivalency.
Organizational Affiliation:
Department of Biotechnology, Jožef Stefan Institute, Jamova 39, SI-1000 Ljubljana, Slovenia,. Electronic address: jure.pohleven@ijs.si.
