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>

Abstract

Bacteria form biofilms as an adaptive mechanism in response to environmental changes. Streptococcus mutans is the biofilm-forming bacterium that is primarily associated with dental caries. The expression of important genes by bacteria in biofilms is different from that of planktonic cells. Lectins are proteins that bind specifically to carbohydrates and may have important biological activities on bacterial cells, acting as antibacterial and anti-biofilm agents. ConM (Canavalia maritima lectin) is a protein that is able to inhibit the planktonic growth and biofilm formation of S. mutans. In this context, this study aimed to evaluate the effects of ConM and concanavalin A (ConA) on the expression of genes related to virulence and biofilm formation in S. mutans. The results showed that ConM significantly reduced the expression of genes encoding enzymes related to adhesion, formation and regulation of biofilms. On the contrary, ConA did not alter the expression of the genes studied. Because the two lectins have a high degree of similarity, the differences in the actions of ConM and ConA may be explained by the small structural differences in the carbohydrate recognition domain of the lectins.

Lectins as antimicrobial agents

“…Cavalcante et al . () showed that Streptococcus mutans cells treated with Canavalia maritima lectin (ConM) had reduced expression of genes related with biofilm formation and regulation as well as drug resistance. A lectin from the haemolymph of crab Portunus pelagicus was able to reduce biofilm thickness of Citrobacter amalonatius , Proteus vulgaris , P. aeruginosa and V. parahaemolyticus in 62, 90, 75 and 88%, respectively, with disruption of biofilm architecture (Jayanthi et al .…”

Multi-effect of the water-solubleMoringa oleiferalectin againstSerratia marcescensandBacillussp.: antibacterial, antibiofilm and anti-adhesive properties

“…Other mechanisms cited in studies that report antibiofilm activity of lectins involve their binding to constituents of the biofilm exopolymeric matrix, interrupting its polymerization and as anti‐ quorum sensing molecules, preventing the expression of genes required for biofilm development and for other virulence factors (Cavalcante et al . ; Klafke et al . ; Hasan et al .…”

“…In addition, the interactions between bacterial cells and lectins may also be linked to the inhibitory effect on biofilm formation by preventing the interactions between bacterial polysaccharides and surfaces as well as between other bacterial cells. Other mechanisms cited in studies that report antibiofilm activity of lectins involve their binding to constituents of the biofilm exopolymeric matrix, interrupting its polymerization and as anti-quorum sensing molecules, preventing the expression of genes required for biofilm development and for other virulence factors (Cavalcante et al 2013;Klafke et al 2013;Hasan et al 2014).…”

“…The interactions between lectins and sugars play important roles in several biological processes and mediate a broad range of biological activities, including antibacterial and antibiofilm activities (Klafke et al 2013;Dias et al 2015). Several studies have reported that these proteins are able to affect bacterial growth and viability as well as to disrupt the bacterial intracellular signaling (quorum sensing) involved in the formation of biofilms (Islam et al 2009;Cavalcante et al 2013;Saha et al 2014).…”

Plant lectins as alternative tools against bacterial biofilms

“…Santi-Gadelha and colleagues (2006), using electron microscopy, observed the pre- Cavalcante et al 2561 sence of pores and severe disruption of bacterial membrane of Gram-positive, confirming the marked antimicrobial activity and pointing a possible mechanism of growth inhibition by lectins, since these pores formed in the membrane allows the output of the cell content (Terras et al, 1993;. By the genetic expression analysis of genes related to the S. mutans biofilm on Canavalia maritime lectin, Cavalcante et al (2013) observed that although the mechanism of action of these lectins requires a better understanding, the results reported in that 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.…”