One century of ConA and 40 years of ConBr research: A structural review

Lectins are proteins that can bind specifically and reversibly to carbohydrates. This capacity gives lectins multiple biological roles and biotechnological applications. Although lectins can be found in all organisms, plant lectins, especially legume lectins, are undoubtedly the most thoroughly studied. Among legume lectins, the lectin from Canavalia ensiformis (ConA) and Canavalia brasiliensis (ConBr), both from Diocleinae subtribe, are two of the most well-known lectins. It has been 100 years since the first report of ConA and 40 years since the first report of ConBr, making 2019 an important year for lectinology. Structural data of these lectins in combination with biological activity tests clearly indicate that even a small shift in amino acid sequence can affect the tertiary and quaternary structures, consequently affecting the biological activity of these proteins. It is in this context that the present paper aims to review the structural data of ConA and ConBr, focusing on the primary structure, crystallography, tertiary and quaternary structures of these lectins, as well as their binding sites. This paper also expands the structural data by employing molecular dynamics to evaluate carbohydrate-binding properties and structural stability. It is anticipated that these data will increase knowledge about the structure-function relationships of these proteins.