Bile-mediated activation of the acrAB and tolC multidrug efflux genes occurs mainly through transcriptional derepression of ramA in Salmonella enterica serovar Typhimurium

2014 ◽  
Vol 69 (9) ◽  
pp. 2400-2406 ◽  
Author(s):  
S. Baucheron ◽  
K. Nishino ◽  
I. Monchaux ◽  
S. Canepa ◽  
M.-C. Maurel ◽  
...  
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Multidrug Efflux ◽  
Serovar Typhimurium ◽  
Transcriptional Derepression

scholarly journals Regulation of the AcrAB multidrug efflux pump in Salmonella enterica serovar Typhimurium in response to indole and paraquat

Microbiology ◽  
2011 ◽  
Vol 157 (3) ◽  
pp. 648-655 ◽  
Author(s):  
Eiji Nikaido ◽  
Ikue Shirosaka ◽  
Akihito Yamaguchi ◽  
Kunihiko Nishino
Keyword(s):  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Efflux Pump ◽  
Upstream Region ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Extracellular Signals ◽  
Multidrug Efflux Pumps ◽  
Serovar Typhimurium ◽  
Binding Sequence

Salmonella enterica serovar Typhimurium has at least nine multidrug efflux pumps. Among these, AcrAB is constitutively expressed and is the most efficient, playing a role in both drug resistance and virulence. The acrAB locus is induced by indole, Escherichia coli-conditioned medium, and bile salts. This induction is dependent on RamA through the binding sequence in the upstream region of acrA that binds RamA. In the present study, we made a detailed investigation of the ramA and acrAB induction mechanisms in Salmonella in response to indole, a biological oxidant for bacteria. We found that acrAB and ramA induction in response to indole is dependent on RamR. However, the cysteine residues of RamR do not play a role in the induction of ramA in response to indole, and the oxidative effect of indole is therefore not related to ramA induction via RamR. Furthermore, we showed that paraquat, a superoxide generator, induces acrAB but not ramA. We further discovered that the mechanism of acrAB induction in response to paraquat is dependent on SoxS. The data indicate that there are at least two independent induction pathways for acrAB in response to extracellular signals such as indole and paraquat. We propose that Salmonella utilizes these regulators for acrAB induction in response to extracellular signals in order to adapt itself to environmental conditions.

scholarly journals H-NS Modulates Multidrug Resistance of Salmonella enterica Serovar Typhimurium by Repressing Multidrug Efflux Genes acrEF

2009 ◽  
Vol 53 (8) ◽  
pp. 3541-3543 ◽  
Author(s):  
Kunihiko Nishino ◽  
Mitsuko Hayashi-Nishino ◽  
Akihito Yamaguchi
Keyword(s):  
Multidrug Resistance ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Efflux Pump ◽  
Multidrug Efflux ◽  
Multidrug Efflux Pump ◽  
Serovar Typhimurium

ABSTRACT Screening of Salmonella mutants for the ability to increase β-lactam resistance has led to the identification of a mutation in hns, which codes for the histone-like nucleoid structuring protein (H-NS). In this study, we report that H-NS modulates multidrug resistance through repression of the genes that encode the AcrEF multidrug efflux pump in Salmonella enterica serovar Typhimurium.

Sign in / Sign up

Export Citation Format

Share Document