Estudos estruturais, clonagem e expressão e atividade biológica da lectina de Canavalia bonariensis

Abstract

Recognition between proteins and carbohydrates is fundamental in many biological processes, such as viral, bacterial and parasitic infections, separation of cells and soluble components, fertilization, growth, differentiation and cancer metastasis. Changes in glycosylation patterns present in these affected cells are striking evidence of these disorders and disease progression. Within this problematic the use of lectin can facilitate, therefore, the discovery of new biomarkers, considering that they are proteins able to bind specifically and reversibly to carbohydrates. Among the plant lectins, the most extensively studied are those isolated from the legume family species, with emphasis in this work the lectin of Canavalia bonariensis (CaBo), a lectin glucose/mannose specific. In the present work, we report the crystalline structure of CaBo determined in atomic resolution in the presence of α-methyl-mannoside, a specific ligand. Similar to the structural characteristics of other legume lectins, CaBo presented the jellyroll motif and a metal binding site occupied by calcium ions and manganese near the carbohydrate recognition domain (CRD). The cytotoxic potential of CaBo on glioma cell cultures of C6 lines (rat) was investigated and the results demonstrated its ability to affect cell viability and migration by autophagy induction and cell death, suggesting the potential antiglioma for the lectin. In order to investigate the mechanisms of action of this protein, the structural aspects of the lectin were analyzed through the tools of docking and molecular dynamics. The results corroborate with previous data indicating that the biological activity of lectin occurs mainly through interactions with glycoproteins, since lectin interacted favorably with several N-glycans and also demonstrated its interaction stability with mannose-type binders. Thus, in view of the biotechnological potential already reported for this lectin, the production of the recombinant form of CaBo in a heterologous system was also sought through this work, so that rCaBo was properly expressed using E. coli cells.