Structural characterization of a galectin isolated from the marine sponge Chondrilla caribensis with leishmanicidal potential.

Background: Solving primary structure of lectins leads to an understanding of the physiological roles within an organism and its biotechnological potential. Only eight sponge lectins have had their primary structure fully determined.

Methods: The primary structure of CCL, Chondrilla caribensis lectin, was determined by tandem mass spectrometry. The three-dimensional structure was predicted and the protein-carbohydrate interaction analysed by molecular docking. Furthermore, the anti-leishmanial activity was observed by assays with Leishmania infantum.

Results: The amino acid sequence consists of 142 amino acids with a calculated molecular mass of 15,443 Da. The lectin has a galectin-like domain architecture. As observed in other sponge galectins, the signature sequence of a highly conserved domain was also identified in CCL with some modifications. CCL exhibits a typical galectin structure consisting of a β-sandwich. Molecular docking showed that the amino acids interacting with CCL ligands at the monosaccharide binding site are mostly the same as those conserved in this family of lectins. Through its interaction with L. infantum glycans, CCL was able to inhibit the development of this parasite. CCL also induced apoptosis after eliciting ROS production and altering the membrane integrity of Leishmania infantum promastigote.

Conclusions: CCL joins the restricted group of sponge lectins with determined primary structure and very high biotechnological potential owing to its promising results against pathogens that cause Leishmaniasis.

General Significance: As the determination of primary structure is important for biological studies, now CCL can become a sponge galectin with an exciting future in the field of human health.