Protein-Carbohydrate Interactions at the Atomic Level:
Studies of Legume Lectins

Nathan Sharon, Hansjörg Streicher and Rivka Adar
Department of Biological Chemistry

Tel. (+972)-8-9343605, Fax. (+972)-8-9468256, email:

Objectives of Research:
Lectins, nonenzymic proteins that bind mono-and oligosaccharides reversibly and with high specificity, are ubiquitous in nature. They act as mediators of cellular recognition in a variety of systems. Understanding the atomic basis of lectin carbohydrate interactions is of interest not only for theoretical reasons, but also for the design of novel drugs for treatment of a wide range of diseases, from microbial infections and inflammatory diseases to cancer. Plant lectins have been attracting much attention because of their ease of isolation and their usefulness as reagents for glycoconjugates in solution and on cell surfaces. The largest family of plant lectins are those obtained from seeds of the legumes. Over 80 such lectins are known, and to the extent examined they all exhibit extensive homologies and possess superimposable tertiary structures. Recently, they have been shown to be structurally similar to animal lectins, some of which are involved in the control of protein traffic in cells. We are using legume lectins as models for the investigation of protein-carbohydrate interactions.

Recent findings:
High resolution X-ray crystallography of the complex of the Gal/GalNAc-specific Erythrina corallodendron lectin (ECorL) with lactose identified the amino acid side chains that form contacts with the galactose moiety of the disaccharide [Shaanan, Lis and Sharon, (1991) Science 254, 862]. We have also cloned the lectin and expressed it in Escherichia coli [Arango et al, (1992) Eur. J. Biochem. 205, 575], making it possible to evaluate by site directed mutagenesis the contribution of these amino acids to the binding of different monosaccharides and oligosaccharides by the lectin.

Comparison with other legume lectins specific for mannose/glucose, galactose, N-acetylgalactosamine, L-fucose or N-acetylglucosamine, shows that only three of the combining site residues of ECorL occupy invariant positions both in their primary and tertiary structures. These are an aspartic acid and an asparagine corresponding to residues 89 and 133, respectively, in ECorL, and an aromatic residue, either phenylalanine (as Phe131 in ECorL), tyrosine or tryptophan. We therefore postulate that these three residues are essential for ligand binding by all such lectins, irrespective of their specificity.

[Figure 1]

The combining sites of lectins from other families, whether from plants (e.g., cereals), or animals (the selectins and galectins), differ markedly from those of the legumes. Thus, Nature finds different solutions for the design of binding sites for strucurally similar ligands, such as monosaccharides, just as it provides diverse solutions for other functions of proteins.

We have recently cloned and expressed soybean agglutinin in monkey cells (in collaboration with S. Rozenblatt, Tel Aviv University) and wish to examine the combining site of this legume lectin as done for ECorL. We are also starting to construct chimeric legume lectins to understand the basis of their ability to distinguish between galactose and glucose, that differ in the configuration of an hydroxyl at a single carbon atom (C-4). For this purpose, we shall use the cDNAs of ECorL and pea lectin (the latter a gift from Jan Kijne, Leiden University), express the chimeric cDNAs in E.coli and characterize the expressed proteins.

Fig. 1: Model of N-acetyllactosamine in the combining site of Erythrina corallodendron lectin.




  (* Primary publications)




501. Abraham, S.N., Sharon, N. and Ofek, I. (2002) In Medical Molecular Microbiology (ed. M. Sussman) Academic Press. Pp. 629-644. Adhesion and colonization.

502. Burger, O., Weiss, E., Sharon., N. (2002) Crit. Revs. Food Sci. Nutrition 42 (Suppl 3), 279-284. Inhibition of Helicobacter pylori adhesion to human gastric mucus by a high-molecular weight constituent of cranberry juice.

503. Ofek. I. and Sharon, N. (2002) CMLS, Cell Mol. Life Sci. 59, 1666-1667. Visions and Reflections: A bright future for antiadhesion therapy of infectious diseases.

504. Sharon, N. (2002) Chemtracts – Biochem. Molec. Biol. 15, 748. Proteoglycan Protocols: Methods Molec. Biol. Volume 171. (Book Review).

505.Sharon, N. and Lis, H. (2002). Wiley Encyclopedia of Molecular Medicine. pp. 1901-1903. Lectins.

506. Sharon, N. and Lis, H. (2002) Encyclopedia of Life Sciences 10, 657-665. Nature Publishing Group. Lectins.

507. Sharon, N. and Lis, H. (2002) J. Agric. Food Chem. 50, 6586-91. How proteins bind carbohydrates: lessons from legume lectins.

508. Sharon, N. and Ofek, I. (2002) Crit. Revs. Food Sci. Nutrtion 42 267-272. Fighting infectious diseases with inhibitors of microbial adhesion to host tissues.

509. *Svensson, C., Teneberg, S., Nilsson, C.L., Schwarz, F.P., Kjellberg, A., Sharon, N. and Krengel, U. (2002) J. Mol. Biol. 321, 69-83. High-resolution crystal structures of Erythrina cristagalli lectin in complex with lactose and 2’-a-L-fucosyllactose and their correlation with thermodynamic binding data.

510. Weiss, E. L., Lev-Dor, R., Sharon, N. and Ofek, I. (2002) Crit. Rev. Food Sci. Nutr. 42 (Suppl 3), 285-92. Inhibitory effect of a high-molecular-weight constituent of cranberry on adhesion of oral bacteria.

511. Wormald, M. and Sharon, N. (2002) Current Opin. Struct. Biol. 12 567-568. Hot roles for glycosylation: signal transduction, control of cell development and differentiation, and innate immunity. (Editorial overview).






*512. Ebner S, Sharon N and Ben-Tal N. (2003) Proteins 53, 44-55. Evolutionary analysis reveals collective properties and specificity in the C-type lectin and lectin-like domain superfamily.

*513. Mitra, N., Sharon, N. and Surolia, I. (2003) Biochemistry 42, 12208-12216. Role of glycosylation in modulating folding behaviour of a glycoprotein lectin from Erythrina corallodendron.

515. Ofek, I., Hasty, D. L. and Sharon, N. (2003) FEMS Immunol. Med. Microbiol. 38, 181-191. Antadhesion therapy of microbial diseases: problems and prospects.

515a. Sharon, N. (2002) In memory of Kozo and Reiko Hamaguchi.

516. Sharon, N and Lis, H. (2003) Lectins (Second edn.) 470 pp., Kluwer Academic Publishers.

517. Streicher, H. and Sharon, N. (2003) Methods Enzymol 363, 47-77. Recombinant plant lectins and their mutants.





518. Abraham, S., Bishop, B. Sharon, N. and Ofek, I. (2004) In Mucosal Immunology (Third edn,) Elsevier (Eds Mestecky et al.) pp. 35-48. Adhesion of bacteria to mucosal surfaces.

*519. Ben-Dor, S., Esterman, N., Rubin, E. and Sharon, N (2004) Glycobiology 14, 1-7. Biases and complex patterns in the residues flanking protein N-glycosylation.

*520. Bonneil, E., Young, N.M., Lis, H., Sharon, N. and Thibault, P. (2004) Arch. Biochem. Biophys 426, 241-249. Probing genetic variants and glycoforms distribution in lectins of the Erythrina genus using mass spectrometry.

*521. Kulkarni KA, Srivastava, A., Mitra, N., Sharon N., Surolia, A, Vijayan, M and Suguna, K. (2004) Proteins 56, 821-27. Effect of glycosylation on the structure of Erythrina corallodendron lectin.

522. Sharon, N. (2004) Glycobiology 14, 23G. Karl Meyer, lysozyme and penicillin

523. Sharon, N. (2004) Oxford Dictionary National Biography. Albert Neuberger.

524. Sharon, N and Lis, H. (2004) Encyclopedia Biological Chemistry 535-540. Lectins.

525. Sharon, N and Lis, H. (2004) Glycobiology 14, 53R-62R. History of lectins: from hemagglutinins to biological recognition determinants.

*526. Shmuely, S, Burger, O., Neeman, I., Yahav, Y., Samra, Z., Niv, Y., Sharon, N., Weiss, E., Athamna, A., Tabak, M. and Ofek, I. Diagnostic Microbiol. Infect. Disease 50, 231-235. Susceptibility of Helicobacter pylori isolates to the anti-adhesion activity of a high-molecular-weight constituent of cranberry.

*527. Weis, E. Steinberg, D., Lev-Dor, R., Bar Ness Greenstein, R., Feldman, M., Sharon, N. and Ofek, I. (2004) FEMS Microbiol. Lett. 232, 89-92. A high molecular weight cranberry constituent reduces mutant streptococci level in saliva and inhibits in vitro adhesion to hydroxyapatite.

528. Wormald, M.R. and Sharon, N. (2004) Current Opin. Struct. Biol. 14, 591. Carbohydrates and glycoconjugates. Progress in non-mammalian glycosylation, glycosyltransferases, invertebrate lectins and carbohydrate-carbohydrate interactions (Editorial overview).







*529. Duncan, M. J., Mann E. L., Cohen M. S., Ofek I, Sharon N and Abraham S. N. (2005) J. Biol. Chem. 280, 377707-37716. The distinct binding specificities exhibited by enterobacterial type 1 fimbriae are determined by their fimbrial shafts.

530. Sharon, N. (2005) Cell. Mol. Life Sci. 62, 1057-1062. Memories of a senior scientist: A life with lectins.

531. Sharon, N. (2005) Scientific American 202 (5), 5. On guard (Letter to the editor – Lectins in innate immunity).

532. Sharon, N. (2005) Glycoconjugate J. 22, 79. Advances in Macromolecular Carbohydrate Research, Ed. R. J. Sturgeon. (Book review).





533. Lapid, K. and Sharon N. (2006) Glycobiology 15, 39R-45R. Meet the sexy glycoforms of glycodelin.

534. Sharon, N. (2006) The Biochemist (Special issue on Glycobiology) 28, 13-17. Protein-carbohydrate interactions – at the heart of biochemistry.

535. Sharon, N. (2006) in “Protein-carbohydrate interactions and their role in infection and disease” Royal Society of Chemistry, London (Ed. C. Bewley). Chapter 1, pp. 1-5. Atomic basis of carbohydrate-protein interactions: an overview.

536. Sharon, N. (2006) Biochim. Biophys. Acta 1760, 527-537. Carbohydrates as future anti-adhesion drugs for infectious diseases.

536a. Sharon, N and Lis, H. (2006) Lectins (Japanese translation of second edn.) Osawa T., Konamy, Y. and Yamamoto, K.) 560 pp., Springer-Verlag Tokyo.

537. Sharon, N. and Ofek, I., (2006) in “Protein-carbohydrate interactions and their role in infection and disease” Royal Society of Chemistry, London ). Chapter 4, pp. 49-72.) Protein-carbohydrate interactions in enterobacterial infections.





*538. Itakura, Y, Nakamura-Tsuruta, S, Kominami, J , Sharon, N, Kasai, K. and Hirabayashi, J. (2007) J. Biochem (Tokyo) 142, 459-469. Systematic comparison of oligosaccharide specificity of Ricinus communis agglutinin I and Erythrina lectins: a search by frontal affinity chromatography,

539. Sharon, N. (2007) J. Biol. Chem. 282, 2753-2764. Reflections: Lectins, carbohydrate-specific reagents and cell recognition molecules.

540. Sharon, N. (2007) Glycobiology 17, 1150-1155. Celebrating the golden anniversary of the discovery of bacillosamine, the diamino sugar of a Bacillus.

541. Sharon, N. and Gallagher, J. (2007) Current Opin. Struct. Biol. 17, 1-4. Glycobiology marching on (Editorial overview)

542. Sharon, N. and Ofek, I. (2007) Microbial lectins In “Comprehensive Glycobiology” (Eds. J. Kamerling et al.) Vol. 3, 623-659.

542a. Sharon, N. (2007) In Glycobiology (Eds C. Samson & O. Markman) Scion Publishers Limited, pp. 363-367. Afterword.

*543 Wu, A. M., Wu, J. H., Tsai, M., Yang, Z., Sharon, N. and Herp, A. (2007) Glycoconjugate J. 24, 591-564. Differential affinities of Erythrina cristagalli lectin (ECL) toward monosaccharides and polyvalent mammalian structural units.





544. Abu-Qarn, M., Eichler, J. ana Sharon, N. (2008) Curent Opin. Struct. Biol 18, (in press). Protein glycosylation in archaebacteria and eubacteria.

545.Esko, J. D. and Sharon, N. (2008) Chapter 34 in “Essentials of Glycobiology” (Second edn., in press) Cold Spring Harbor Laboratory Press (Ed. A. Varki et al.) Microbial adhesins, viral agglutinins and toxins.

546. Sahly, H., Keisari, Y., Crouch, E., Sharon, N. and Ofek, I. (2008), Infect. Immun. 76, 1322-1332. Recognition of bacterial surface polysaccharides by lectins of the innate immune system and its contribution to defense against infection: the case of pulmonary pathogens.

547. Sharon, N. (2008) Biochem. Soc. Trans. (in press). Lectins: Past, present and future.

548. Sharon, N., Glick, M. C. and Hughes, R. C. (2008) Glycobiology 18, 206-208.

In memory of Roger W. Jeanloz, a pioneer glycobiologist (1917-2007)

549. Varki, A. and Sharon, N. (2008) Chapter 1 pp. 1-22 in “Essentials of Glycobiology” (Second edn., in press) Cold Spring Harbor Laboratory Press (Eds. A. Varki et al.) Historical background and overview.





Curriculum Vitae