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GSE33871
Pseudomonas aeruginosa pao1
15 Downloadable Samples
Affymetrix Pseudomonas aeruginosa Array (paeg1a)
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 (Kings 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.
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View Samples- Pseudomonas aeruginosa pao1
- 8 Downloadable Samples
- Affymetrix Pseudomonas aeruginosa Array (paeg1a)
Description
Characterization of bacterial behavior in the microgravity environment of spaceflight is of importance towards risk assessment and prevention of infectious disease during long-term missions. Further, this research field unveils new insights into connections between low fluid-shear regions encountered by pathogens during their natural infection process in vivo, and bacterial virulence. This study is the first to characterize the global transcriptomic and proteomic response of an opportunistic pathogen that is actually found in the space habitat, Pseudomonas aeruginosa. Overall, P. aeruginosa responded to spaceflight conditions through differential regulation of 167 genes and 28 proteins, with Hfq identified as a global transcriptional regulator in the response to this environment. Since Hfq was also induced in spaceflight-grown Salmonella typhimurium, Hfq represents the first spaceflight-induced regulator across the bacterial species border. The major P. aeruginosa virulence-related genes induced in spaceflight conditions were the lecA and lecB lectins and the rhamnosyltransferase (rhlA), involved in the production of rhamnolipids. The transcriptional response of spaceflight-grown P. aeruginosa was compared with our previous data of this organism grown in microgravity-analogue conditions using the rotating wall vessel (RWV) bioreactor technology. Interesting similarities were observed, among others with regard to Hfq regulation and oxygen utilization. While LSMMG-grown P. aeruginosa mainly induced genes involved in microaerophilic metabolism, P. aeruginosa cultured in spaceflight adopted an anaerobic mode of growth, in which denitrification was presumably most prominent. Differences in hardware between spaceflight and LSMMG experiments, in combination with more pronounced low fluid shear and mixing in spaceflight when compared to LSMMG conditions, were hypothesized to be at the origin of these observations. Collectively, our data suggest that spaceflight conditions could induce the transition of P. aeruginosa from an opportunistic organism to potential pathogen, results that are of importance for infectious disease risk assessment and prevention, both during spaceflight missions and in the clinic.
Publication Title
Transcriptional and proteomic responses of Pseudomonas aeruginosa PAO1 to spaceflight conditions involve Hfq regulation and reveal a role for oxygen.
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View Samples- Pseudomonas aeruginosa pao1
- 8 Downloadable Samples
- Affymetrix Pseudomonas aeruginosa Array (paeg1a)
Description
Anticipating the risk for infectious disease during space exploration and habitation is a critical factor to ensure safety, health and performance of the crewmembers. As a ubiquitous environmental organism that is occasionally part of the human flora, Pseudomonas aeruginosa could pose a health hazard for the immuno-compromised astronauts. In order to gain insights in the behavior of P. aeruginosa in spaceflight conditions, two spaceflight-analogue culture systems, i.e. the rotating wall vessel (RWV) and the random position machine (RPM), were used. Microarray analysis of P. aeruginosa PAO1 grown in the low shear modeled microgravity (LSMMG) environment of the RWV compared to the normal gravity control (NG), revealed a regulatory role for AlgU (RpoE). Specifically, P. aeruginosa cultured in LSMMG exhibited increased alginate production and up-regulation of AlgU-controlled transcripts, including those encoding stress-related proteins. This study also shows the involvement of Hfq in the LSMMG response, consistent with its previously identified role in the Salmonella LSMMG- and spaceflight response. Furthermore, cultivation in LSMMG increased heat- and oxidative stress resistance and caused a decrease in the culture oxygen transfer rate. Interestingly, the global transcriptional response of P. aeruginosa grown in the RPM was similar to that in NG. The possible role of differences in fluid mixing between the RWV and RPM is discussed, with the overall collective data favoring the RWV as the optimal model to study the LSMMG-response of suspended cells. This study represents a first step towards the identification of specific virulence mechanisms of P. aeruginosa activated in response to spaceflight-analogue conditions, and could direct future research regarding the risk assessment and prevention of Pseudomonas infections for the crew in flight and the general public.
Publication Title
Response of Pseudomonas aeruginosa PAO1 to low shear modelled microgravity involves AlgU regulation.
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