Transcriptome Analysis of Genes Controlled byluxS/Autoinducer-2 inSalmonella entericaSerovar Typhimurium

Abstract

The enteric pathogen Salmonella enterica serovar Typhimurium uses autoinducer-2 (AI-2) as a signaling molecule. AI-2 requires the luxS gene for its synthesis. The regulation of global gene expression in Salmonella Typhimurium by luxS=AI-2 is currently not known; therefore, the focus of this study was to elucidate the global gene expression patterns in Salmonella Typhimurium as regulated by luxS=AI-2. The genes controlled by luxS=AI-2 were identified using microarrays with RNA samples from wild-type (WT) Salmonella Typhimurium and its isogenic DluxS mutant, in two growth conditions (presence and absence of glucose) at mid-log and early stationary phases. The results indicate that luxS=AI-2 has very different effects in Salmonella Typhimurium depending on the stage of cell growth and the levels of glucose. Genes with p 0.05 were considered to be significantly expressed differentially between WT and DluxS mutant. In the mid-log phase of growth, AI-2 activity was higher (1500-fold) in the presence of glucose than in its absence (450-fold). There was differential gene expression of 13 genes between the WT and its isogenic DluxS mutant in the presence of glucose and 547 genes in its absence. In early stationary phase, AI-2 activity was higher (650-fold) in the presence of glucose than in its absence (1.5-fold). In the presence of glucose, 16 genes were differentially expressed, and in its absence, 60 genes were differentially expressed. Our microarray study indicates that both luxS and AI-2 could play a vital role in several cellular processes including metabolism, biofilm formation, transcription, translation, transport, and binding proteins, signal transduction, and regulatory functions in addition to previously identified functions. Phenotypic analysis of DluxS mutant confirmed the microarray results and revealed that luxS did not influence growth but played a role in the biofilm formation and motility.

Salmonella biofilms: An overview on occurrence, structure, regulation and eradication

“…The Lsr transport system is well-known to be involved in the detection and transport of AI-2 into the cell, while the rbs transporter has recently been suggested as an alternative AI-2 uptake system (Jesudhasan et al, 2010). A number of research groups reported that Salmonella biofilm formation is affected by mutating the luxS gene.…”

“…Prouty et al found that a S. Typhimurium luxS insertion mutant only showed scattered biofilm formation with little apparent EPS on the surface of gallstones after 4 days of incubation (Prouty et al, 2002). Jesudhasan et al reported that a S. Typhimurium luxS deletion mutant is impaired in biofilm formation on polystyrene (Jesudhasan et al, 2010). Microarray analysis revealed that several motility genes and biofilm-related genes are down-regulated in the luxS deletion mutant as compared to the wildtype.…”

Effect of growth media on gene expression levels in Salmonella Typhimurium biofilm formed on stainless steel surface

“…Much research interest on biofilm formation by Salmonella has been focused on confirming the regulatory genes (Jesudhasan et al, 2010). White, Gibson, Kim, Kay, and Surette (2006) have found that thin aggregative fimbriae and cellulose (agfD and agfA) enhance long-term survival and persistence of Salmonella.…”

Attachment and Biofilm Formation by Salmonella in Food Processing Environments

“…The second QS system of Salmonella uses the LuxS enzyme for the synthesis of AI-2 (Schauder et al, 2001;Soni et al, 2008). The Lsr ABC transporter is known to be involved in the detection and transport of AI-2 into the cell (Taga et al, 2001), while the rbs transporter has recently been suggested as an alternative AI-2 uptake system (Jesudhasan et al, 2010). A S. Typhimurium luxS deletion mutant was impaired in biofilm formation on polystyrene (De Keersmaecker et al, 2005;Jesudhasan et al, 2010).…”

“…The Lsr ABC transporter is known to be involved in the detection and transport of AI-2 into the cell (Taga et al, 2001), while the rbs transporter has recently been suggested as an alternative AI-2 uptake system (Jesudhasan et al, 2010). A S. Typhimurium luxS deletion mutant was impaired in biofilm formation on polystyrene (De Keersmaecker et al, 2005;Jesudhasan et al, 2010). However, this phenotype could not be complemented by extracellular addition of QS signal molecules, suggesting that AI-2 is not the actual signal involved in Salmonella biofilm formation (De Keersmaecker et al, 2005).…”