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

3. 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

4. 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

5. Legume lectins: peanut lectin, winged bean basic and
acidic lectins and their complexes
PNAS (1994) 91,
JMB (1996) 259,
JBC (1996) 271,
Curr. Sci. (1997) 72,
JMB (1998) 276,
Glycobiology (1998) 10,
JACS (1998) 120,
Proteins SFG (1999) 35, 58-69
Acta Cryst. (1999) D55,
JMB (2000) 302,
Proteins SFG (2001) 43,
JBC (2001) 276,
Protein Eng. (2001) 14,
Acta Cryst. (2001) D57,
Acta Cryst. (2003) D59,

6. 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

7. Jackfruit

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

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

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

11. Structure and interactions of artocarpin
J. Mol. Biol (2002) 317,
J. Mol. Biol (2004) 338,
Tetrameric, Mr 65,000;
Non-glycosylated;
Mannose-specific

12. Snake gourd

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

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

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

17. Garlic lectin: Re-refinement using reprocessed data
G. Ramachandraiah, Nagasuma R. Chandra, A. Surolia and M. Vijayan
(2002) Acta Cryst. D58,
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

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

20. Man7Gn2Asn 6545 7200 Man8Gn2Asn 14120 Man9Gn2Asn M5 M6 M7 N8 N9 N8 M5

21. 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

22. 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

23. No. of
Single links
Double links
Tri
Penta
Hepta
Octa
Nona 24 70 61 94 3 7 36 20 64

24. M1F-M3E