Concanavalin A

Concanavalin A
Crystallographic structure of a tetramer of jack bean concanavalin A (the monomers are colored cyan, green, red, and magenta respectively). Calcium (gold) and manganese cations (grey) are depicted as spheres.[1]
Identifiers
Organism Canavalia virosa (jackbean)
Symbol ConA
PDB 3CNA More structures
UniProt P81461
Other data

Concanavalin A (ConA) is a lectin (carbohydrate-binding protein) originally extracted from the jack-bean, Canavalia ensiformis. It is a member of the legume lectin family. It binds specifically to certain structures found in various sugars, glycoproteins, and glycolipids, mainly internal and nonreducing terminal α-D-mannosyl and α-D-glucosyl groups.[2][3] ConA is a plant mitogen, and is known for its ability to stimulate mouse T-cell subsets giving rise to four functionally distinct T cell populations, including precursors to suppressor T-cell;[4] one subset of human suppressor T-cells as well is sensitive to ConA.[4] ConA was the first lectin to be available on a commercial basis, and is widely used in biology and biochemistry to characterize glycoproteins and other sugar-containing entities on the surface of various cells.[5] It is also used to purify glycosylated macromolecules in lectin affinity chromatography,[6] as well as to study immune regulation by various immune cells.[4]

Structure and properties

Like most lectins, ConA is a homotetramer: each sub-unit (26.5KDa, 235 amino-acids, heavily glycated) binds a metallic atom (usually Mn2+ and a Ca2+). It has the D2 symmetry.[1] Its tertiary structure has been elucidated,[7] and the molecular basis of its interactions with metals as well as its affinity for the sugars mannose and glucose[8] are well known.

ConA binds specifically α-D-mannosyl and α-D-glucosyl residues (two hexoses differing only by the alcohol on carbon 2) in terminal position of ramified structures from B-Glycans (reach in α-mannose, or hybrid and bi-antennary glycanes complexes). It has 4 binding sites, corresponding to the 4 sub-units.[3] The molecular weight is 104-112KDa and the isoelectric point (pI) is in the range of 4.5-5.5.

Concanavalin A has a low-frequency wave number of 20 cm−1 in its Raman spectra.[9] This emission has been assigned to the breathing motion of the beta barrel consisting of 14 beta-strands in the concanavalin A molecule.[10]

ConA can also initiate cell division (mitogenesis) principally acting on T-lymphocytes, by stimulating the energy metabolism of thymocytes within seconds of exposure.[11]

Biological activity

Concanavalin A interacts with diverse receptors containing mannose carbohydrates, notably rhodopsin, blood group markers, insulin-receptor[12] the Immunoglobulins and the carcino-embryonary antigen (CEA). It also interacts with lipoproteins.[13]

ConA agglutinates strongly erythrocytes irrespective of blood-groups, and various cancerous cells.[14][15][16] It was demonstrated that transformed cells and trypsin-treated normal cells do not agglutinate at 4 °C, thereby initiate suggesting that there is a temperature-sensitive step involved in ConA-mediated agglutination.[17][18]

ConA-mediated agglutination of other cell types has been reported, including muscle cells (myocytes),[19] B-lymphocytes (through surface Immunoglobulins),[20] fibroblasts,[21] rat thymocytes,[22] human fetal (but not adult) intestinal epithelial cells,[23] and adipocytes.[24]

ConA is a lymphocyte mitogen. Similar to phytohemagglutinin (PHA), it is a selective T cell mitogen relative to its effects on B cells. PHA and ConA bind and cross-link components of the T cell receptor, and their ability to activate T cells is dependent on expression of the T cell receptor.[25][26]

ConA interacts with the surface mannose residues of many microbes, like the bacteria E. coli,[27] and Bacillus subtilis[28] and the protist Dictyostelium discoideum.[29]

It has also been shown as a stimulator of several matrix metalloproteinases (MMPs).[30]

ConA has proven useful in applications requiring solid-phase immobilization of glycoenzymes, especially those have proved difficult to immobilize by the traditional covalent coupling. Using ConA-couple matrices, such enzymes may be immobilized in high quantities without a concurrent loss of activity and/or stability. Such noncovalent ConA-glycoenzyme couplings may be relatively easily reversed by competition with sugars or at acidic pH. If necessary for certain applications, these couplings can be converted to covalent bindings by chemical manipulation.[31]

A recent (2009) report from Taiwan demonstrated potent therapeutic effect of ConA against experimental hepatoma (liver cancer); in the study by Lei and Chang,[32] ConA was found to be sequestered more by hepatic tumor cells, in preference to surrounding normal hepatocytes. Internalization of ConA occurs preferentially to the mitochondria after binding to cell membrane glycoproteins, which triggers an autophagic cell death. ConA was found to partially inhibit tumor nodule growth independent of its lymphocyte activation; the eradication of the tumor in the murine in situ hepatoma model in this study was additionally attributed to the mitogenic/lymphoproliferative action of ConA that may have activated a CD8+ T-cell-mediated, as well as NK- and NK-T cell-mediated, immune response in the liver.[32]

References

  1. ↑ 1.0 1.1 PDB 3CNA; Hardman, Karl D.; Ainsworth, Clinton F. (1972). "Structure of concanavalin a at 2.4-Ang resolution". Biochemistry 11 (26): 4910–9. doi:10.1021/bi00776a006. PMID 4638345.
  2. ↑ Goldstein, Irwin J.; Poretz, Ronald D. (2012). "Isolation, physicochemical characterization, and carbohydrate-binding specificity of lectins". In Liener, Irvin E.; Sharon, Nathan; Goldstein, Irwin J. The Lectins Properties, Functions and Applications in Biology and Medicine. Elsevier. pp. 33–247. ISBN 978-0-323-14444-5.
  3. ↑ 3.0 3.1 Sumner, J. B.; Gralen, N.; Eriksson-Quensel, I.-B. (1938). "The Molecular Weights of Urease, Canavalin, Concanavalin a and Concanavalin B". Science 87 (2261): 395–6. Bibcode:1938Sci....87..395S. doi:10.1126/science.87.2261.395. PMID 17746464.
  4. ↑ 4.0 4.1 4.2 Dwyer, J. M.; Johnson, C (1981). "The use of concanavalin a to study the immunoregulation of human T cells". Clinical and experimental immunology 46 (2): 237–49. PMC 1536405. PMID 6461456.
  5. ↑ Schiefer, H. G.; Krauss, H; Brunner, H; Gerhardt, U (1975). "Ultrastructural visualization of surface carbohydrate structures on mycoplasma membranes by concanavalin A". Journal of bacteriology 124 (3): 1598–600. PMC 236075. PMID 1104592.
  6. ↑ GE Healthcare Life Sciences, Immobilized lectin
  7. ↑ Min, W; Dunn, A. J.; Jones, D. H. (1992). "Non-glycosylated recombinant pro-concanavalin a is active without polypeptide cleavage". The EMBO journal 11 (4): 1303–7. PMC 556578. PMID 1563347.
  8. ↑ Loris, Remy; Hamelryck, Thomas; Bouckaert, Julie; Wyns, Lode (1998). "Legume lectin structure". Biochimica et Biophysica Acta (BBA) - Protein Structure and Molecular Enzymology 1383 (1): 9–36. doi:10.1016/S0167-4838(97)00182-9. PMID 9546043.
  9. ↑ Painter, P. C.; Mosher, L. E.; Rhoads, C. (1982). "Low-frequency modes in the Raman spectra of proteins". Biopolymers 21 (7): 1469–72. doi:10.1002/bip.360210715. PMID 7115900.
  10. ↑ Chou, K.C. (1985). "Low-frequency motions in protein molecules. Beta-sheet and beta-barrel". Biophysical Journal 48 (2): 289–97. Bibcode:1985BpJ....48..289C. doi:10.1016/S0006-3495(85)83782-6. PMC 1329320. PMID 4052563.
  11. ↑ Krauss, Stefan; Buttgereit, Frank; Brand, Martin D. (1999). "Effects of the mitogen concanavalin a on pathways of thymocyte energy metabolism". Biochimica et Biophysica Acta (BBA) - Bioenergetics 1412 (2): 129–38. doi:10.1016/S0005-2728(99)00058-4. PMID 10393256.
  12. ↑ Cuatrecasas, P.; Tell, G. P. E. (1973). "Insulin-Like Activity of Concanavalin a and Wheat Germ Agglutinin--Direct Interactions with Insulin Receptors". Proceedings of the National Academy of Sciences 70 (2): 485–9. Bibcode:1973PNAS...70..485C. doi:10.1073/pnas.70.2.485. JSTOR 62526. PMC 433288. PMID 4510292.
  13. ↑ Harmony, J. A.; Cordes, E. H. (1975). "Interaction of human plasma low density lipoprotein with concanavalin a and with ricin". The Journal of biological chemistry 250 (22): 8614–7. PMID 171260.
  14. ↑ Betton, G. R. (1976). "Agglutination reactions of spontaneous canine tumour cells, induced by concanavalin a, demonstrated by an isotopic assay". International Journal of Cancer 18 (5): 687–96. doi:10.1002/ijc.2910180518. PMID 992901.
  15. ↑ Kakizoe, T; Komatsu, H; Niijima, T; Kawachi, T; Sugimura, T (1980). "Increased agglutinability of bladder cells by concanavalin a after administration of carcinogens". Cancer research 40 (6): 2006–9. PMID 7371036.
  16. ↑ Becker, F. F.; Shurgin, A (1975). "Concanavalin a agglutination of cells from primary hepatocellular carcinomas and hepatic nodules induced by N-2-fluorenylacetamide". Cancer research 35 (10): 2879–83. PMID 168971.
  17. ↑ Inbar, M.; Ben-Bassat, H.; Sachs, L. (1971). "A Specific Metabolic Activity on the Surface Membrane in Malignant Cell-Transformation". Proceedings of the National Academy of Sciences 68 (11): 2748–51. Bibcode:1971PNAS...68.2748I. doi:10.1073/pnas.68.11.2748. JSTOR 61219. PMC 389516. PMID 4330939.
  18. ↑ Sela, B; Lis, H; Sharon, N; Sachs, L (1971). "Quantitation of N-acetyl-d-galactosamine-like sites on the surface membrane of normal and transformed mammalian cells". Biochimica et Biophysica Acta (BBA) - Biomembranes 249 (2): 564–8. doi:10.1016/0005-2736(71)90132-5. PMID 4332414.
  19. ↑ Kent Gartner, T.; Podieski, T.R. (1975). "Evidence that a membrane bound lectin mediates fusion of L6 myoblasts". Biochemical and Biophysical Research Communications 67 (3): 972–8. doi:10.1016/0006-291X(75)90770-6. PMID 1201086.
  20. ↑ De Petris, S. (1975). "Concanavalin a receptors, immunoglobulins, and theta antigen of the lymphocyte surface. Interactions with concanavalin a and with Cytoplasmic structures". The Journal of Cell Biology 65 (1): 123–46. doi:10.1083/jcb.65.1.123. PMC 2111157. PMID 1092699.
  21. ↑ Noonan, K. D.; Burger, M. M. (1973). "The Relationship of Concanavalin a Binding to Lectin-Initiated Cell Agglutination". The Journal of Cell Biology 59 (1): 134–42. doi:10.1083/jcb.59.1.134. PMC 2110924. PMID 4201706.
  22. ↑ Capo, C; Garrouste, F; Benoliel, A. M.; Bongrand, P; Ryter, A; Bell, G. I. (1982). "Concanavalin-A-mediated thymocyte agglutination: A model for a quantitative study of cell adhesion". Journal of cell science 56: 21–48. PMID 7166565.
  23. ↑ Weiser, M. M. (1972). "Concanavalin a Agglutination of Intestinal Cells from the Human Fetus". Science 177 (4048): 525–6. Bibcode:1972Sci...177..525W. doi:10.1126/science.177.4048.525. PMID 5050484.
  24. ↑ Cuatrecasas, Pedro (1973). "Interaction of wheat germ agglutinin and concanavalin a with isolated fat cells". Biochemistry 12 (7): 1312–23. doi:10.1021/bi00731a011. PMID 4696755.
  25. ↑ Weiss, A; Shields, R; Newton, M; Manger, B; Imboden, J (1987). "Ligand-receptor interactions required for commitment to the activation of the interleukin 2 gene". Journal of immunology 138 (7): 2169–76. PMID 3104454.
  26. ↑ Kanellopoulos, Jean M.; De Petris, Stefanello; Leca, Gerald; Crumpton, Michael J. (1985). "The mitogenic lectin from Phaseolus vulgaris does not recognize the T3 antigen of human T lymphocytes". European Journal of Immunology 15 (5): 479. doi:10.1002/eji.1830150512. PMID 3873340.
  27. ↑ Ofek, I.; Mirelman, D.; Sharon, N. (1977). "Adherence of Escherichia coli to human mucosal cells mediated by mannose receptors". Nature 265 (5595): 623–5. Bibcode:1977Natur.265..623O. doi:10.1038/265623a0. PMID 323718.
  28. ↑ Doyle, R. J.; Birdsell, D. C. (1972). "Interaction of concanavalin a with the cell wall of Bacillus subtilis". Journal of bacteriology 109 (2): 652–8. PMC 285189. PMID 4621684.
  29. ↑ West, C. M.; McMahon, D (1977). "Identification of concanavalin a receptors and galactose-binding proteins in purified plasma membranes of Dictyostelium discoideum". The Journal of Cell Biology 74 (1): 264–73. doi:10.1083/jcb.74.1.264. PMC 2109878. PMID 559679.
  30. ↑ Yu, M; Sato, H; Seiki, M; Thompson, E. W. (1995). "Complex regulation of membrane-type matrix metalloproteinase expression and matrix metalloproteinase-2 activation by concanavalin a in MDA-MB-231 human breast cancer cells". Cancer research 55 (15): 3272–7. PMID 7614461.
  31. ↑ Saleemuddin, M.; Husain, Qayyum (1991). "Concanavalin A: A useful ligand for glycoenzyme immobilization—A review". Enzyme and Microbial Technology 13 (4): 290–5. doi:10.1016/0141-0229(91)90146-2. PMID 1367163.
  32. ↑ 32.0 32.1 Lei, Huan-Yao; Chang, Chih-Peng (2009). "Lectin of Concanavalin a as an anti-hepatoma therapeutic agent". Journal of Biomedical Science 16: 10. doi:10.1186/1423-0127-16-10. PMC 2644972. PMID 19272170.

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