Project description:The study aimed to identify role of OxyR during growth on different electron acceptors when E. coli are growing anaerobically. Wt and OxyR null cells were grown on nitrate and fumarate medium anaerobically. Each condition was done in duplicate. RNA was extracted using Qiagen RNeasy kit after stabilization of RNA with RNA protect bacteria reagent. Hybridization and further processing was done based on Affymetrix protocols on E. coli Genome 2.0 arrays.
Project description:Oxidative stress caused by exposure to reactive oxygen species (ROS), is a major challenge for aerobic and especially anaerobic organisms. Bacteria coordinate the response to oxidative stress through the LysR-type transcriptional regulator (LTTR) OxyR. Extensive studies have focused on the classical Escherichia coli system to shed light on the mode of action of defensive weapons against oxidative stress. The underlying mechanism is mediated via the formation of redox-dependent disulfide bond between two conserved cysteines of OxyR, thus activating transcription of members of the OxyR regulon. However, only fragmentary information on the regulation and function of OxyR has been gleaned through genetic and biochemical analyses in the important opportunistic pathogen P. aeruginosa. In this report, we used a comprehensive transcriptional profiling analysis to delineate the OxyR regulon under three conditions (King’s A medium [Pseudomonas medium or PM], Luria Broth (LB), and LB when oxyR is overexpressed), to investigate its roles in different cellular aspects that are independent of the classical oxidative stress response. Interestingly, when grown in LB, OxyR was found to regulating many genes involved in the process of inter-cellular communication known as quorum sensing (QS). In contrast, when grown in PM, OxyR regulate the expression of a newly identified CSS (cell-surface signaling) system in an OxyR-dependent fashion. In addition, the results from oxyR overexpression further confirmed that OxyR was linked to regulation of QS and Type 3 Secretion (T3SS) in addition to the regulation of antioxidative genes. Taken together, our results show that, apart from its dominant role in defense against oxidative stress in P. aeruginosa, OxyR acts as a global regulator that provides a link between the regulation of oxidative stress response, QS and virulence.
Project description:Oxidative stress that originates from reactive oxygen species (ROS) is an inevitable consequence of aerobic respiration in bacteria. Three transcription factors (TFs), OxyR, SoxR, and SoxS play a critical role in transcriptional regulation of the defense system. However, the full genome-wide regulatory potential of them remains elusive. Here, we comprehensively reconstruct genome-wide OxyR, SoxR, and SoxS transcriptional regulatory networks in Escherichia coli under oxidative stress. Integrative data analysis reveals that OxyR, SoxR, and SoxS regulons are comprised of 38 genes in 28 transcription units (TUs), 11 genes in 10 TUs, and 34 genes in 25 TUs, respectively, significantly expanding the current knowledge of their regulatory networks. Comparison of them to other stress-response regulatory networks highlights minimal overlap between their regulons, indicating that E. coli has a series of relatively distinct stress responses covering the range of different stresses. We also demonstrate that these intricate networks coordinate detoxification process with DNA and protein damage repair, cell wall synthesis, divalent metal ion homeostasis, as well as metabolic robustness to produce overall response of E. coli to oxidative stress.
Project description:Oxidative stress that originates from reactive oxygen species (ROS) is an inevitable consequence of aerobic respiration in bacteria. Three transcription factors (TFs), OxyR, SoxR, and SoxS play a critical role in transcriptional regulation of the defense system. However, the full genome-wide regulatory potential of them remains elusive. Here, we comprehensively reconstruct genome-wide OxyR, SoxR, and SoxS transcriptional regulatory networks in Escherichia coli under oxidative stress. Integrative data analysis reveals that OxyR, SoxR, and SoxS regulons are comprised of 38 genes in 28 transcription units (TUs), 11 genes in 10 TUs, and 34 genes in 25 TUs, respectively, significantly expanding the current knowledge of their regulatory networks. Comparison of them to other stress-response regulatory networks highlights minimal overlap between their regulons, indicating that E. coli has a series of relatively distinct stress responses covering the range of different stresses. We also demonstrate that these intricate networks coordinate detoxification process with DNA and protein damage repair, cell wall synthesis, divalent metal ion homeostasis, as well as metabolic robustness to produce overall response of E. coli to oxidative stress.
Project description:Oxidative stress caused by exposure to reactive oxygen species (ROS), is a major challenge for aerobic and especially anaerobic organisms. Bacteria coordinate the response to oxidative stress through the LysR-type transcriptional regulator (LTTR) OxyR. Extensive studies have focused on the classical Escherichia coli system to shed light on the mode of action of defensive weapons against oxidative stress. The underlying mechanism is mediated via the formation of redox-dependent disulfide bond between two conserved cysteines of OxyR, thus activating transcription of members of the OxyR regulon. However, only fragmentary information on the regulation and function of OxyR has been gleaned through genetic and biochemical analyses in the important opportunistic pathogen P. aeruginosa. In this report, we used a comprehensive transcriptional profiling analysis to delineate the OxyR regulon under three conditions (KingM-bM-^@M-^Ys A medium [Pseudomonas medium or PM], Luria Broth (LB), and LB when oxyR is overexpressed), to investigate its roles in different cellular aspects that are independent of the classical oxidative stress response. Interestingly, when grown in LB, OxyR was found to regulating many genes involved in the process of inter-cellular communication known as quorum sensing (QS). In contrast, when grown in PM, OxyR regulate the expression of a newly identified CSS (cell-surface signaling) system in an OxyR-dependent fashion. In addition, the results from oxyR overexpression further confirmed that OxyR was linked to regulation of QS and Type 3 Secretion (T3SS) in addition to the regulation of antioxidative genes. Taken together, our results show that, apart from its dominant role in defense against oxidative stress in P. aeruginosa, OxyR acts as a global regulator that provides a link between the regulation of oxidative stress response, QS and virulence. 15 samples, representing 5 different biological conditions, including 3 biological replicates for each condition
Project description:Oxidative stress that originates from reactive oxygen species (ROS) is an inevitable consequence of aerobic respiration in bacteria. Three transcription factors (TFs), OxyR, SoxR, and SoxS play a critical role in transcriptional regulation of the defense system. However, the full genome-wide regulatory potential of them remains elusive. Here, we comprehensively reconstruct genome-wide OxyR, SoxR, and SoxS transcriptional regulatory networks in Escherichia coli under oxidative stress. Integrative data analysis reveals that OxyR, SoxR, and SoxS regulons are comprised of 38 genes in 28 transcription units (TUs), 11 genes in 10 TUs, and 34 genes in 25 TUs, respectively, significantly expanding the current knowledge of their regulatory networks. Comparison of them to other stress-response regulatory networks highlights minimal overlap between their regulons, indicating that E. coli has a series of relatively distinct stress responses covering the range of different stresses. We also demonstrate that these intricate networks coordinate detoxification process with DNA and protein damage repair, cell wall synthesis, divalent metal ion homeostasis, as well as metabolic robustness to produce overall response of E. coli to oxidative stress. A total of six samples were analyzed. oxyR-8myc, soxR-8myc, and soxS-8myc tagged cells were cultured in M9 minimal media with 0.2% glucose. Then cells were treated with 250 uM of paraquat at mid-log pahse for 20 min with agitation.
Project description:Xenorhabdus nematophila is a Gram-negative bacterium, mutually associated with the soil nematode Steinernema carpocapsae and this nematobacterial complex is parasitic for a broad spectrum of insects. The transcriptional regulator OxyR is widely conserved in bacteria, but the OxyR regulon can vary significantly between species. OxyR activates the transcription of a set of genes that influence cellular defense against oxidative stress. It is also involved in the virulence of several bacterial pathogens. The aim of this study was to identify the X. nematophila OxyR regulon and investigate its role in the bacterial life cycle. An oxyR-mutant was constructed in X. nematophila and phenotypically characterized in vitro and in vivo after reassociation with its nematode partner. OxyR plays a major role during the X. nematophila resistance to oxidative stress in vitro. Transcriptome analysis allowed the identification of 59 genes differentially regulated in the oxyR mutant compared to the parental strain. In vivo, the oxyR mutant was able to reassociate with the nematode as efficiently as the control strain. These nematobacterial complexes harboring the oxyR mutant symbiont were able to rapidly kill the insect larvae in less than 48h after infestation, suggesting that factors other than OxyR could also allow X. nematophila to cope with oxidative stress encountered during this phase of infection in insect. The significant increased number of offspring of the nematobacterial complex when reassociated with the X. nematophila oxyR mutant compared to the control strain, revealed a potential role of OxyR during this symbiotic stage of the bacterial life-cycle.