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Multivalency in Lectins

M. Vijayan. Molecular Biophysics Unit Indian Institute of Science Bangalore 560012. Multivalency in Lectins. Plant Lectin Families. I Legume lectins Jelly roll II Cereal lectins Hevein domain

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Multivalency in Lectins

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  1. M. Vijayan Molecular Biophysics Unit Indian Institute of Science Bangalore 560012 Multivalency in Lectins

  2. Plant Lectin Families I Legume lectins Jelly roll II Cereal lectins Hevein domain III Moraceae lectins -prism I IV Bulb lectins -prism II V Ricin, Amaranthin etc -trefoil

  3. Legume lectins: peanut lectin, winged bean basic and acidic lectins and their complexes Peanut lectin (PNA) Tetramer, Mr 1,10,000; Non-glycosylated; galactose specific; specific to T-antigen (Gal1-3GalNAc) at disaccharide level Basic winged bean lectin (WBA I) Dimer, Mr 58,000; glycosylated; Gal/GalNAc specific; specific to blood group A and less to B, does not bind O Acidic winged bean lectin (WBA II) Dimer, Mr 58,000; glycosylated; Gal/GalNAc specific; specific to blood group O and binds weakly to A and B

  4. Legume lectins: peanut lectin, winged bean basic and acidic lectins and their complexes • PNAS (1994) 91, 227-231 • JMB (1996) 259, 281-291 • JBC (1996) 271, 21209-21213 • Curr. Sci. (1997) 72, 855-861 • JMB (1998) 276, 787-796 • Glycobiology (1998) 10, 1007-1012 • JACS (1998) 120, 11297-11303 • Proteins SFG (1999) 35, 58-69 • Acta Cryst. (1999) D55, 1375-1382 • JMB (2000) 302, 1129-1137 • Proteins SFG (2001) 43, 260-270 • JBC (2001) 276, 40734-40739 • Protein Eng. (2001) 14, 857-866 • Acta Cryst. (2001) D57, 1584-1594 • Acta Cryst. (2003) D59, 2254-2256

  5. Legume lectins: peanut lectin, winged bean basic and acidic lectins and their complexes • Multimeric proteins can assume open • quaternary structures • High variability in quaternary structure • while the tertiary structure is essentially • same • Water bridges as a strategy for generating • ligand specificity • Role of loop length and aromatic interactions • in generating carbohydrate specificity • Structure-based mutational studies

  6. Jackfruit

  7. Jacalin: A lectin from jackfruit seeds Nat. Struct. Biol. (1996) 3, 596-603 J. Mol. Biol. (2002) 321, 637-645 J. Mol. Biol. (2003) 332, 217-228 • Tetramer, Mr 66,000; glycosylated; Gal/GalNAc specific; Specific to T-antigen at disaccharide level • New lectin fold characteristic of the moraceae family

  8. Hydrogen-bonding interactions between jacalin and galactose • Post translational proteolysis is used as a strategy for • generating ligand specificity

  9. Composite view of binding region Secondary site A Secondary site B Primary site

  10. Structure and interactions of artocarpin J. Mol. Biol (2002) 317, 237-247 J. Mol. Biol (2004) 338,757-770 • Tetrameric, Mr 65,000; • Non-glycosylated; • Mannose-specific

  11. Snake gourd

  12. Structure of snake gourd lectin Acta Cryst. (2001) D57, 912-914 • Heterodimeric, Mr 62,000; • Glycosylated; • Galactose specific • Amino acid sequence not available • Structure similar to that of typeII • RIP’s

  13. Snake gourd lectin has no ribosome inactivating property Red SGSL Blue Trichosanthin

  14. Structure and interactions of garlic lectin JMB (1999) 285, 1157-1168 • Dimeric, Mr 24,000; • Non-glycosylated; • Mannose specific

  15. Garlic lectin: Re-refinement using reprocessed data G. Ramachandraiah, Nagasuma R. Chandra, A. Surolia and M. Vijayan (2002) Acta Cryst. D58, 414-420 XDS X-PLOR DENZO CNS • Resolution increased from 2.8Å (effective) to 2.2Å • Isolectins could be identified with confidence • Asymmetric unit contains two heterodimers. Better • definition of the structure

  16. 2 4 6 Garlic lectin-olygosaccharide interactions G. Ramachandraiah, Nagasuma R. Chandra, A. Surolia and M. Vijayan (2003) Glycobiology 13, 765-775 11.6 NI 7.3 8.6 Man1-2Man Man1-4Man Man1-6Man Man1-3Man 28.8 29.0 Man5 Man3

  17. M5 N8 N9 M6 M7 M5 N9 N10 M6 M7 M8 Man7Gn2Asn 6545 N8 7200 Man8Gn2Asn 14120 Man9Gn2Asn

  18. Single cross-linking • Tri : 6 × 6: 36 • Penta : 12 × 6: 72 • Hepta : 12 × 6: 72 • Octa : 12 × 6: 72 • Nona : 12 × 6: 72 Accepted pairs of dimers: Short contacts <=20

  19. Double cross-linking Term. pairs: 12C2 Site pairs: 6P2 Total: 12C2 ×6P2 :1980 |Tij-Sij| <=3.0 Å Accepted pairs of dimers: Short contacts <=40

  20. M1F-M3E

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