Low expression of AcrB in the deoxycholate-sensitive strains of Salmonella enterica subspecies enterica serovar Pullorum

Usui, Masaru; Asai, Tetsuo; Sato, Shizuo

doi:10.1111/j.1348-0421.2011.00321.x

Cited by 4 publications

(4 citation statements)

References 10 publications

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“…Furthermore, the AcrAB-TolC system had the highest gene expression when the bile salt concentration was 0.5%. Previous research has shown that bile salts can regulate the expression of acrAB and tolC multidrug efflux genes in E. coli, S. typhimurium, and intestinal serous pullorum (Rosenberg et al, 2003;Usui et al, 2011;Baucheron et al, 2014). Our experimental results indicated that the effect of bile salts could significantly increase the gene expression of the AcrAB-TolC system in C. malonaticus, which confirmed that the AcrAB-TolC system in C. malonaticus is an essential system for the excretion of bile salts.…”

Section: Expression Of Acrab-tolc System Under Bile Salt Stresssupporting

confidence: 83%

Effects of tolC on tolerance to bile salts and biofilm formation in Cronobacter malonaticus

Wang

Ling

et al. 2021

Journal of Dairy Science

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Bile salts is one of essential components of bile secreted into the intestine to confer antibacterial protection. Cronobacter species are associated with necrotizing enterocolitis in newborns and show a strong tolerance to bile salts. However, little attempt has been made to focus on the molecular basis of the tolerance to bile salts. In this study, we investigated the roles of tolC on growth, cell morphology, motility, and biofilm formation ability in Cronobacter malonaticus under bile salt stress. The results indicated that the absence of tolC significantly affected the colony morphology and outer membrane structure in a normal situation, compared with those of the wild type strain. The deletion of tolC caused the decline in resistance to bile salt stress, inhibition of growth, and observable reduction in relative growth rate and motility. Moreover, the bacterial stress response promoted the biofilm formation ability of the mutant strain. The expression of the AcrAB-TolC system (acrA, acrB, and tolC) was effectively upregulated compared with the control sample when exposed to different bile salt concentrations. The findings provide valuable information for deeply understanding molecular mechanisms about the roles of tolC under bile salt stress and the prevention and control of C. malonaticus.

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Section: Expression Of Acrab-tolc System Under Bile Salt Stresssupporting

confidence: 83%

Effects of tolC on tolerance to bile salts and biofilm formation in Cronobacter malonaticus

Wang

Ling

et al. 2021

Journal of Dairy Science

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“…As the mechanism responsible for bile susceptibility in three deoxycholate-sensitive strains of Salmonella enterica subspecies enterica serovar Pullorum was investigated, the expression of AcrB mRNA was 10-fold lower in the deoxycholate-sensitive strains than in a deoxycholate-resistant strain. These results suggested that low expression of AcrB was strongly correlated with bile susceptibility in the deoxycholate-sensitive strains [25].…”

Section: Discussionmentioning

confidence: 80%

AcrB is essential for bile acid tolerance in Helicobacter pylori

Minami¹,

Hashikawa²,

Ando³

et al. 2022

GSC Adv. Res. Rev.

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Resistance to bile acids is a necessary ability for bacteria that live in the gastrointestinal tract, such as Helicobacter pylori. The role of the bacterial drug efflux system is important for bile acid tolerance. Using the H. pylori JP26 strain and the JP26AcrB strain deficient in AcrB the relationship between the drug efflux system AcrB and the bile acid tolerance of H. pylori was investigated. Bacterial susceptibility to bile acids was measured by the agar dilution method. To examine the ability to efflux bile acids, the intracellular accumulation of radiolabeled chenodeoxycholic acid was measured with a liquid scintillation counter. To investigate the effect of bile acid on the cell adhesion ability of bacteria, bacteria were attached to AGS cells supplemented with chenodeoxycholic acid, and the number of bacteria was counted. Bile acid resistance was significantly lower in the AcrB mutant than in the wild-type strain. The AcrB mutant strains showed a significant increase in the accumulation of 14C - labeled chenodeoxycholic acid in the bacteria. In terms of attachment to AGS cells, the AcrB mutant was significantly lower than the wild-type strain. Furthermore, the AcrB mutant with chenodeoxycholic acid could not be identified. Our results reveal that H. pylori AcrB plays an important role in bile acid resistance. We also suggest that drugs targeting the AcrB efflux system may be a new treatment for H. pylori.

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“…To evaluate the genes conferring efflux pump activity and their multiple global regulators, quantitative PCR was applied to the detection and quantification of mRNAs (Usui et al, 2010, 2011). The preparation of cDNA was performed as described by Zheng et al (2009), with slight modifications.…”

Section: Methodsmentioning

confidence: 99%

“…In S . Pullorum, the expression of acrB , which shifts from sensitivity to resistance against bile salt (deoxycholate, an AcrAB substrate), was independent of ramA , soxS , marA , and rob expression (Usui et al, 2011). …”

Section: Introductionmentioning

confidence: 99%

Effect of Antimicrobial Exposure on AcrAB Expression in Salmonella enterica Subspecies enterica Serovar Choleraesuis

et al. 2013

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Understanding the impact of antimicrobial use on the emergence of resistant bacteria is imperative to prevent its emergence. For instance, activation of the AcrAB efflux pumps is responsible for the emergence of antimicrobial-resistant Salmonella strains. Here, we examined the expression levels of acrB and its multiple regulator genes (RamA, SoxS, MarA, and Rob) in 17 field isolates of S. Choleraesuis by using quantitative PCR methods. The expression of acrB increased in eight of the field isolates (P < 0.05). The expression of acrB was associated with that of ramA in one isolate, soxS in one isolate, and both these genes in six isolates. Thereafter, to examine the effect of selected antimicrobials (enrofloxacin, ampicillin, oxytetracycline, kanamycin, and spectinomycin) on the expression of acrB and its regulator genes, mutants derived from five isolates of S. Choleraesuis were selected by culture on antimicrobial-containing plates. The expression of acrB and ramA was higher in the mutants selected using enrofloxacin (3.3–6.3- and 24.5–37.7-fold, respectively), ampicillin (1.8–7.7- and 16.1–55.9-fold, respectively), oxytetracycline (1.7–3.3- and 3.2–31.1-fold, respectively), and kanamycin (1.6–2.2- and 5.6–26.4-fold, respectively), which are AcrAB substrates, than in each of the parental strains (P < 0.05). In contrast, in AcrAB substrate-selected mutants, the expression of soxS, marA, and rob remained similar to that in parental strains. Of the four antimicrobials, the level of ramA expression was significantly higher in the enrofloxacin- and ampicillin-selected mutants than in the oxytetracycline- and kanamycin-selected mutants (P < 0.05), whereas the expression levels of acrB and multiple regulator genes in spectinomycin-selected mutants were similar to those in each parental strain. These data suggest that exposure to antimicrobials that are AcrAB substrates enhance the activation of the AcrAB efflux pump via RamA, but not via SoxS, MarA, or Rob in S. Choleraesuis.

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Low expression of AcrB in the deoxycholate-sensitive strains of Salmonella enterica subspecies enterica serovar Pullorum

Cited by 4 publications

References 10 publications

Effects of tolC on tolerance to bile salts and biofilm formation in Cronobacter malonaticus

Effects of tolC on tolerance to bile salts and biofilm formation in Cronobacter malonaticus

AcrB is essential for bile acid tolerance in Helicobacter pylori

Effect of Antimicrobial Exposure on AcrAB Expression in Salmonella enterica Subspecies enterica Serovar Choleraesuis

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