Structural analysis of ConBr reveals molecular correlation between the carbohydrate recognition domain and endothelial NO synthase activation

Abstract

Diocleinae lectins are highly homologous in their primary structure which features metal binding sites and a carbohydrate recognition domain (CRD). Differences in the biological activity of legume lectins have been widely investigated using hemagglutination inhibition assays, isothermal titration microcalorimetry and co-crystallization with mono- and oligosaccharides. Here we report a new lectin crystal structure (ConBr) extracted from seeds of Canavalia brasiliensis, predict dimannoside binding by docking, identify the α-aminobutyric acid (Abu) binding pocket and compare the CRD of ConBr to that of homologous lectins. Based on the hypothesis that the carbohydrate affinity of lectins depends on CRD configuration, the relationship between tridimensional structure and endothelial NO synthase activation was used to clarify differences in biological activity. Our study established a correlation between the position of CRD amino acid side chains and the stimulation of NO release from endothelium.

Toxicity and Binding Profile of Lectins from the GenusCanavaliaon Brine Shrimp

“…These differences arise from changes in three major physicochemical parameters: binding specificity for complex carbohydrates, the pH-dependent oligomerization state (dimer-tetramer equilibrium), and the relative orientation of the carbohydrate-binding sites. The smallest CRD volume of ConBr among other Canavalia lectins has been shown to be the major reason of its lower activation of nitric oxide synthase in aortic endothelial cells [35]. In this study, the smallest CRD volume of ConBr proved to be the major reason of its high toxicity on brine shrimp.…”

Structural Studies of an Anti-Inflammatory Lectin from Canavalia boliviana Seeds in Complex with Dimannosides

“…It has been reported that the relative position of the carbohydrate-binding site and pH-dependent dimer-tetramer equilibrium contribute to these differences [12]; [13]; [14]. The substitution of one amino acid residue related to the carbohydrate-binding site has been held responsible for a more open carbohydrate-binding site in the lectin from Canavalia brasiliensis compared to ConA ( Canavalia ensiformis lectin) resulting in distinct activities [15]; [16]. Minor changes in the amino acid composition are also responsible for the different affinities and biological activities of the Canavalia maritima lectin [17]; [18]; [19].…”

A ConA-like lectin isolated from <i>Canavalia maritima</i> seeds alters the expression of genes related to virulence and biofilm formation in <i>Streptococcus mutans</i>

“…According to Cavada and colleagues [34], small changes in the configuration of important amino acids from the carbohydrate recognition domain (CRD), as well as variations in pH-dependent oligomerization, may explain the differences in biological activities. Moreover, Bezerra and colleagues [35] showed that not only are the configuration and distances between residues in the CRD crucial to explain the difference in activity between Diocleinae lectins, but the volume of the CRD also plays an important role in the lectin activity. The distances between the amino acid residues involved in interactions with carbohydrates are different in ConM and ConA ( Table 2), and the CRD of ConA shows a lower volume when compared with ConM.…”

“…The distances between the amino acid residues involved in interactions with carbohydrates are different in ConM and ConA ( Table 2), and the CRD of ConA shows a lower volume when compared with ConM. The volumes for ConA PDB 1JBC and ConM PDB 2CWM are 151 and 135 Å 3 respectively, suggesting a plausible explanation for the differences in the antimicrobial actions of such lectins [35]. Although the mechanism of action of these lectins requires a better understanding, the results reported in the present article suggest that ConM acts by starting or interrupting intracellular signaling pathways that culminate with the lowest expression of genes associated with virulence and biofilm formation in S. mutans.…”