Project description:In the current study, RNA sequencing was used to investigate the synergistic effects of the berberine and roemerine on Bacillus subtilis cells.
Project description:Multidrug (MDR) efflux pumps are ancient and conserved molecular machineries with relevant roles in different aspects of the bacterial physiology, besides antibiotic resistance. In the case of the environmental opportunistic pathogen Pseudomonas aeruginosa, it has been shown that overexpression of different efflux pumps is linked to the impairment of the quorum sensing (QS) response. Nevertheless, the causes of such impairment are different for each analyzed efflux pump. Herein, we performed an in-depth analysis of the QS-mediated response of a P. aeruginosa antibiotic resistant mutant that overexpresses MexAB-OprM. Although previous work claimed that this efflux pump extrudes the QS signal 3-oxo-C12-HSL, we show otherwise. Our results evidence that the observed attenuation in the QS response when overexpressing this pump is related to an impaired production of alkyl quinolone QS signals, likely prompted by the reduced availability of one of their precursors, the octanoate. Together with previous studies, this indicates that, although the consequences of overexpressing efflux pumps are similar (impaired QS response), the underlying mechanisms are different. This ‘apparent redundancy' of MDR efflux systems can be understood as a P. aeruginosa strategy to keep the robustness of the QS regulatory network and modulate its output in response to different signals.
Project description:The study is about the role of Bacteroides thetaiotaomicron in the human gut microbiota, specifically its ability to form biofilms in response to bile salts. The study found that bile induces the expression of certain efflux pumps, and inhibiting these pumps impairs biofilm formation. Among the induced pumps, the BipABC pump is crucial for biofilm formation as it is involved in the efflux of magnesium, which affects the biofilm's extracellular matrix and structure. This discovery sheds light on how intestinal chemical cues, like bile salts, regulate biofilm formation in B. thetaiotaomicron, a significant gut symbiont.
Project description:We used DNA microarrays to define the physiological roles of the Tap efflux pump in M. bovis BCG during the exponential and the stationary phase of in vitro growth. For this purpose we constructed a M. bovis BCG strain in which the tap gene was inactivated by the insertion of a hygromycin resistance cassette (Ω-hyg). When the gene expression patterns of the tap mutant were compared to the wild-type strain, almost no differences were observed during exponential growth; only seven genes slightly increased their expression. In contrast, more that 100 genes showed a variation in their level of expression during stationary growth. More than ten representative genes were chosen from the microarray experiments and their expression was measured by quantitative RT-PCR using sigA as invariant internal control. In support to the gene expression profiling data, the mRNA levels of all selected genes was significantly different in the tap mutant strain relative to control. A functional category analysis (http://tuberculist.epfl.ch/index.html) of the genes differentially expressed revealed a high proportion belonging to the Virulence, Detoxification, Adaptation (VDA), Intermediary Metabolism and Respiration (IMR), Conserved Hypotheticals (CH), and Cell Wall and Cell Processing (CWCP) categories suggesting a major adaptation to a stress generated by inactivation of the tap efflux pump gene.
Project description:Few are the studies that analyzed the molecular features implicated to the tolerance to bile salts by A.baumannii clinical strains. Interestingly, Ab421 GEIH-2010 strain (belonging to ST79/PFGE-HUI-1 clone constitute by isolates with lacking of the AdeABC efflux pump) and A.baumannii ∆adeB ATCC 17978 showed higher tolerance to bile salts by the expression of the glutamate/aspartate transporter as well as virulence factors (Type VI Secretion System, twitching motility and biofilm) associated to the activation of the Quorum Sensing system.
Project description:We used DNA microarrays to define the physiological roles of the Tap efflux pump in M. bovis BCG during the exponential and the stationary phase of in vitro growth. For this purpose we constructed a M. bovis BCG strain in which the tap gene was inactivated by the insertion of a hygromycin resistance cassette (?-hyg). When the gene expression patterns of the tap mutant were compared to the wild-type strain, almost no differences were observed during exponential growth; only seven genes slightly increased their expression. In contrast, more that 100 genes showed a variation in their level of expression during stationary growth. More than ten representative genes were chosen from the microarray experiments and their expression was measured by quantitative RT-PCR using sigA as invariant internal control. In support to the gene expression profiling data, the mRNA levels of all selected genes was significantly different in the tap mutant strain relative to control. A functional category analysis (http://tuberculist.epfl.ch/index.html) of the genes differentially expressed revealed a high proportion belonging to the Virulence, Detoxification, Adaptation (VDA), Intermediary Metabolism and Respiration (IMR), Conserved Hypotheticals (CH), and Cell Wall and Cell Processing (CWCP) categories suggesting a major adaptation to a stress generated by inactivation of the tap efflux pump gene. We compared the global gene expression of the tap mutant versus the wild-type strain of M. bovis BCG during the exponential (one week; OD540= 0.2-0.3) and stationary (six weeks; OD540= 0.8-1.0) growth. Hybridizations were performed using RNA extracted from two different biological samples. Each sample was hybridized twice through swap labeling of the respective cDNAs.
Project description:The acquisition of multi-drug resistance (MDR) determinants jeopardizes treatment of bacterial infections with antibiotics. The tripartite efflux pump AcrAB-NodT confers adaptive MDR in the non-pathogenic α-proteobacterium Caulobacter crescentus via transcriptional induction by first-generation quinolone antibiotics. We discovered that overexpression of AcrAB-NodT by mutation or exogenous inducers confers resistance to cephalosporin and penicillin (β-lactam) antibiotics. Combining two-step mutagenesis-sequencing (Mut-Seq) and cephalosporin-resistant point mutants, we dissected how TipR targets a common operator of divergent tipR and acrAB-nodT promoter in adaptive and/or potentiated AcrAB-NodT-directed efflux. Chemical screening identified compounds that either interfere with DNA-binding by TipR or induce its ClpXP-dependent proteolytic turnover. We found that long-term induction of AcrAB-NodT disfigures the envelope and that homeostatic control by TipR includes co-induction of the DnaJ-like co-chaperone DjlA, to boost pump assembly and/or capacity in anticipation of envelope stress. Thus, the adaptive MDR regulatory circuitry reconciles drug efflux with co-chaperone function for trans-envelope assemblies and maintenance.
Project description:The acquisition of multi-drug resistance (MDR) determinants jeopardizes treatment of bacterial infections with antibiotics. The tripartite efflux pump AcrAB-NodT confers adaptive MDR in the non-pathogenic α-proteobacterium Caulobacter crescentus via transcriptional induction by first-generation quinolone antibiotics. We discovered that overexpression of AcrAB-NodT by mutation or exogenous inducers confers resistance to cephalosporin and penicillin (β-lactam) antibiotics. Combining two-step mutagenesis-sequencing (Mut-Seq) and cephalosporin-resistant point mutants, we dissected how TipR targets a common operator of divergent tipR and acrAB-nodT promoter in adaptive and/or potentiated AcrAB-NodT-directed efflux. Chemical screening identified compounds that either interfere with DNA-binding by TipR or induce its ClpXP-dependent proteolytic turnover. We found that long-term induction of AcrAB-NodT disfigures the envelope and that homeostatic control by TipR includes co-induction of the DnaJ-like co-chaperone DjlA, to boost pump assembly and/or capacity in anticipation of envelope stress. Thus, the adaptive MDR regulatory circuitry reconciles drug efflux with co-chaperone function for trans-envelope assemblies and maintenance.