A report on the crystal structure of a lectin isolated from Canavalia …

• Abstract
• Background
• Results and discussion
• Conclusion
• Methods
• Abbreviations used
• References
• Figures
• Tables

Biology Articles » Mycology » Structure of a lectin from Canavalia gladiata seeds: new structural insights for old molecules

Abstract

- Structure of a lectin from Canavalia gladiata seeds: new structural insights for old molecules

Structure of a lectin from Canavalia gladiata seeds: new structural insights for old molecules

Plínio Delatorre^1 ,2, Bruno AM Rocha^1 ,2, Emmanuel P Souza¹, Taianá M Oliveira¹, Gustavo A Bezerra¹, Frederico BMB Moreno³, Beatriz T Freitas², Tatiane Santi-Gadelha³, Alexandre H Sampaio¹, Walter F Azevedo Jr^4 ,5 and Benildo S Cavada¹

¹Departamento de Bioquímica e Biologia Molecular, Universidade Federal do Ceará, Ceará, Brazil
²Departamento de Biologia, Universidade Regional do Cariri, Ceará, Brazil
³Departamento de Biologia, Universidade Federal da Paraíba, Paraíba, Brazil
⁴Departamento de Física, IBILCE, Universidade Estadual Paulista, São Paulo, Brazil
⁵Faculdade de Biociências, PUCRS, Av. Ipiranga 6681, Zip Code 90619-900, Porto Alegre, RS, Brazil

Background

Lectins are mainly described as simple carbohydrate-binding proteins. Previous studies have tried to identify other binding sites, which possible recognize plant hormones, secondary metabolites, and isolated amino acid residues. We report the crystal structure of a lectin isolated from Canavalia gladiata seeds (CGL), describing a new binding pocket, which may be related to pathogen resistance activity in ConA-like lectins; a site where a non-protein amino-acid, α-aminobutyric acid (Abu), is bound.

Results

The overall structure of native CGL and complexed with α-methyl-mannoside and Abu have been refined at 2.3 Å and 2.31 Å resolution, respectively. Analysis of the electron density maps of the CGL structure shows clearly the presence of Abu, which was confirmed by mass spectrometry.

Conclusion

The presence of Abu in a plant lectin structure strongly indicates the ability of lectins on carrying secondary metabolites. Comparison of the amino acids composing the site with other legume lectins revealed that this site is conserved, providing an evidence of the biological relevance of this site. This new action of lectins strengthens their role in defense mechanisms in plants.