Estudos estruturais e de expressão heteróloga de lectinas de organismos marinhos com potencial biotecnológico

Abstract

Marine organisms possess bioactive compounds with numerous described biological activities. Among these compounds are lectins, proteins or glycoproteins that exhibit specific and reversible binding to carbohydrates. Structural studies of lectins and their protein-carbohydrate interactions are important, as the glycosylation pattern of the cell surface is the key to understanding the functions of these molecules, providing mechanisms for biotechnological applications. However, information on the structure and specificity of these molecules from marine organisms is still scarce. In this sense, strategies focused on the production of recombinant proteins are important tools for structural studies and for the large-scale production of proteins with a biotechnological focus. This study aimed to produce, in a heterologous system, the marine algae lectin AmL (Amansia multifida lectin) and the marine invertebrate egg lectins ELEL (Echinometra lucunter eggs lectin) and ADEL (Aplysia dactylomela eggs lectin), to characterize them biochemically and structurally, and to evaluate the antibacterial potential of the former in combination with antibiotics. Furthermore, the study aimed to determine the three-dimensional structures of galectins derived from marine sponges, CCL (Chondrilla caribensis lectin) and ALL (Aplysina lactuca lectin), and to evaluate the interaction of these proteins with their respective ligands. The lectin rELEL was not expressed with solubility and functionality, despite attempts in different vectors, numerous expression conditions, and refolding and cotransformation strategies. The recombinant lectin rADEL was expressed in a heterologous system of Komagataella pastoris, which was biologically active, but with unsatisfactory yield. The lectin rAmL was expressed in a heterologous system of Escherichia coli, is biologically active, and biochemically similar to the native protein. rAmL showed antibacterial activity associated with the antibiotic tetracycline against Staphylococcus aureus and E. coli. The both galectins, ALL and CCL, had their three-dimensional structure determined by X-ray crystallography, and the lectin-carbohydrate interaction analyzed by cocrystallization and isothermal titration calorimetry. Therefore, these results significantly expand the structural knowledge about lectins from marine organisms, providing new ideas for the functional understanding of lectins from these organisms, whose structural studies are still scarce.