Estrutura primária parcial, modelagem e docking molecular de uma lectina presente em sementes de Vataireopsis araroba (Aguiar) Ducke

Abstract

Lectins are a class of (glyco)proteins capable of reversibly binding to specific carbohydrates. Lectins from the Dalbergieae tribe have aroused a growing interest in studies on bioprospecting, physical-chemical, structural characterization and biotechnological potential. Among the various biological activities reported in the literature, we have pro and anti-inflammatory, nociceptive, vasorelaxant, antibacterial activity, among others. Vataireopsis araroba lectin (VaL) was isolated from seed flour in a single affinity chromatography step and showed specificity for galactosides. This work aimed to carry out studies to determine the primary (by mass spectrometry) and three-dimensional (by bioinformatics) structure of VaL. The results obtained were the determination of the partial amino acid sequence of VaL, whose sequence alignment analyzes showed that the lectin presented a high degree of identity, in relation to its primary structure, and a high degree of coverage with other lectins of the tribe Dalbergieae specific for N-acetylgalactosamine/galactose, such as Vatairea macrocarpa lectin. The secondary structure prediction showed a great predominance of beta sheets, with a percentage of 41.2% and 1.28% of α-helix. The glycosylation profile showed N-glycosylation sites on asparagine residues at positions 111, 114 and 183 of the primary structure of VaL. The determination of the three-dimensional structure was carried out by the homology modeling method, where the protomer presented a conformational pattern similar to that of other Leguminosae lectins, being constituted by the jellyroll motif. Residues participating in the metal binding site (MBS) and carbohydrate recognition domain (CRD) were highly conserved compared to VML.

Finally, molecular docking analyzes revealed favorable interactions with the Tn and N- acetylgalactosamine antigens with scores of -45.01 and -37.06, respectively. The Tn

ligand is an important cancer biomarker, therefore the structural analysis of new lectins that present favorable interactions with this ligand is of considerable interest in order to elucidate the mechanism of specific recognition of the protein-carbohydrate, as well as to develop new tools potential in cancer diagnosis.