%0 Journal Article
%T Effects of indole on drug resistance and virulence of Salmonella enterica serovar Typhimurium revealed by genome-wide analyses
%A Eiji Nikaido
%A Etienne Giraud
%A Sylvie Baucheron
%A Suguru Yamasaki
%A Agn¨¨s Wiedemann
%A Kousuke Okamoto
%A Tatsuya Takagi
%A Akihito Yamaguchi
%A Axel Cloeckaert
%A Kunihiko Nishino
%J Gut Pathogens
%D 2012
%I BioMed Central
%R 10.1186/1757-4749-4-5
%X To understand the complete picture of genes regulated by indole, we performed DNA microarray analysis of genes in the S. enterica serovar Typhimurium strain ATCC 14028s affected by indole. Predicted Salmonella phenotypes affected by indole based on the microarray data were also examined in this study. Indole induced expression of genes related to efflux-mediated multidrug resistance, including ramA and acrAB, and repressed those related to host cell invasion encoded in the Salmonella pathogenicity island 1, and flagella production. Reduction of invasive activity and motility of Salmonella by indole was also observed phenotypically.Our results suggest that indole is an important signaling molecule for inter-species communication to control drug resistance and virulence of S. enterica.Bacteria communicate using small molecules by a process termed quorum sensing. Accumulation of quorum-sensing signals in growth medium indicates cell density. The use of chemical signals for bacterial communication is a widespread phenomenon [1-5]. In Gram-negative bacteria, these signals could be N-acyl derivatives of homoserine lactone, cyclic dipeptides, and quinolones [6-12]. These signals regulate various functions such as bioluminescence, differentiation, virulence, DNA transfer, and biofilm maturation [13-22].The intestinal tract is colonized by approximately 1012 commensal bacteria including those belonging to the genus Escherichia[23-25]. Among Enterobacteriaceae, indole is produced by E. coli and certain Proteeae such as Proteus vulgarisProvidencia spp., and Morganella spp. [26]. Indole production is commonly used for Escherichia coli identification [26]. Indole is generated from tryptophan by the enzyme tryptophanase, encoded by tnaA[27]. Extracellular indole is found at high concentrations (over 600 ¦ÌM) when E. coli is grown in enriched medium [28]. Furthermore, indole has also been found in human feces at comparable concentrations (~250¨C1100 ¦ÌM) [29,30]. Recent studies have
%K AcrAB
%K Indole
%K RamA
%K Salmonella
%K SPI-1
%U http://www.gutpathogens.com/content/4/1/5