4r6r: Difference between revisions

From Proteopedia
Jump to navigation Jump to search
← Older editNewer edit →
No edit summary
No edit summary
Line 11: Line 11:
<div style="background-color:#fffaf0;">
<div style="background-color:#fffaf0;">
== Publication Abstract from PubMed ==
== Publication Abstract from PubMed ==
Jacalin, a tetrameric two-chain lectin (66,000 Mr) from jackfruit seeds, is highly specific for the tumour associated T-antigenic disaccharide. The crystal structure of jacalin with methyl-alpha-D-galactose reveals that each subunit has a three-fold symmetric beta-prism fold made up of three four-stranded beta-sheets. The lectin exhibits a novel carbohydrate-binding site involving the N terminus of the alpha-chain which is generated through a post-translational modification involving proteolysis, the first known instance where such a modification has been used to confer carbohydrate specificity. This new lectin fold may be characteristic of the Moraceae plant family. The structure provides an explanation for the relative affinities of the lectin for galactose derivatives and provides insights into the structural basis of its T-antigen specificity.
Jacalin is among the most thoroughly studied lectins. Its carbohydrate-binding site has also been well characterized. It has been postulated that the lower affinity of beta-galactosides for jacalin compared with alpha-galactosides is caused by steric interactions of the substituents in the former with the protein. This issue has been explored energetically and structurally using different appropriate carbohydrate complexes of jacalin. It turns out that the earlier postulation is not correct. The interactions of the substituent with the binding site remain essentially the same irrespective of the anomeric nature of the substitution. This is achieved through a distortion of the sugar ring in beta-galactosides. The difference in energy, and therefore in affinity, is caused by a distortion of the sugar ring in beta-galactosides. The elucidation of this unprecedented distortion of the ligand as a strategy for modulating affinity is of general interest. The crystal structures also provide a rationale for the relative affinities of the different carbohydrate ligands for jacalin.


A novel mode of carbohydrate recognition in jacalin, a Moraceae plant lectin with a beta-prism fold.,Sankaranarayanan R, Sekar K, Banerjee R, Sharma V, Surolia A, Vijayan M Nat Struct Biol. 1996 Jul;3(7):596-603. PMID:8673603<ref>PMID:8673603</ref>
Jacalin-carbohydrate interactions: distortion of the ligand molecule as a determinant of affinity.,Abhinav KV, Sharma K, Swaminathan CP, Surolia A, Vijayan M Acta Crystallogr D Biol Crystallogr. 2015 Feb;71(Pt 2):324-31. doi:, 10.1107/S139900471402553X. Epub 2015 Jan 23. PMID:25664742<ref>PMID:25664742</ref>


From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>
From MEDLINE&reg;/PubMed&reg;, a database of the U.S. National Library of Medicine.<br>

Revision as of 11:08, 25 February 2015

Jacalin-carbohydrate interactions. Distortion of the ligand as a determinant of affinity.Jacalin-carbohydrate interactions. Distortion of the ligand as a determinant of affinity.

Structural highlights

4r6r is a 8 chain structure with sequence from Artocarpus integer. Full crystallographic information is available from OCA. For a guided tour on the structure components use FirstGlance.
Ligands:, ,
Resources:FirstGlance, OCA, RCSB, PDBsum

Function

[LECA_ARTIN] D-galactose-specific lectin, binds the T-antigen structure Gal-beta1,3-GalNAc (Thomsen-Friedenreich-antigen-specific lectin). Potent and selective stimulant of distinct T- and B-cell functions. Shows a unique ability to specifically recognize IgA-1 from human serum. [LECB3_ARTIN] D-galactose-specific lectin, binds the T-antigen structure Gal-beta1,3-GalNAc (Thomsen-Friedenreich-antigen-specific lectin). Potent and selective stimulant of distinct T- and B-cell functions. Shows a unique ability to specifically recognize IgA-1 from human serum.

Publication Abstract from PubMed

Jacalin is among the most thoroughly studied lectins. Its carbohydrate-binding site has also been well characterized. It has been postulated that the lower affinity of beta-galactosides for jacalin compared with alpha-galactosides is caused by steric interactions of the substituents in the former with the protein. This issue has been explored energetically and structurally using different appropriate carbohydrate complexes of jacalin. It turns out that the earlier postulation is not correct. The interactions of the substituent with the binding site remain essentially the same irrespective of the anomeric nature of the substitution. This is achieved through a distortion of the sugar ring in beta-galactosides. The difference in energy, and therefore in affinity, is caused by a distortion of the sugar ring in beta-galactosides. The elucidation of this unprecedented distortion of the ligand as a strategy for modulating affinity is of general interest. The crystal structures also provide a rationale for the relative affinities of the different carbohydrate ligands for jacalin.

Jacalin-carbohydrate interactions: distortion of the ligand molecule as a determinant of affinity.,Abhinav KV, Sharma K, Swaminathan CP, Surolia A, Vijayan M Acta Crystallogr D Biol Crystallogr. 2015 Feb;71(Pt 2):324-31. doi:, 10.1107/S139900471402553X. Epub 2015 Jan 23. PMID:25664742[1]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.

References

  1. ↑ Abhinav KV, Sharma K, Swaminathan CP, Surolia A, Vijayan M. Jacalin-carbohydrate interactions: distortion of the ligand molecule as a determinant of affinity. Acta Crystallogr D Biol Crystallogr. 2015 Feb;71(Pt 2):324-31. doi:, 10.1107/S139900471402553X. Epub 2015 Jan 23. PMID:25664742 doi:http://dx.doi.org/10.1107/S139900471402553X

4r6r, resolution 1.38Å

Drag the structure with the mouse to rotate

Proteopedia Page Contributors and Editors (what is this?)Proteopedia Page Contributors and Editors (what is this?)

OCA
Retrieved from "https://proteopedia.openfox.io/wiki/index.php?title=4r6r&oldid=2377827"