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Lab evolution, transcriptomics, and modeling reveal mechanisms of paraquat tolerance

ABSTRACT: We use adaptive laboratory evolution to generate strains which tolerate high levels of the redox cycling compound paraquat, which produces reactive oxygen species (ROS). We combine resequencing, iModulon analysis of the transcripome, and metabolic models to elucidate six interacting stress tolerance mechanisms: 1) modification of transport, 2) activation of ROS stress responses, 3) use of ROS-sensitive iron regulation, 4) motility, 5) broad transcriptional reallocation toward growth, and 6) metabolic rewiring to decrease NADH production. This work thus reveals the genome-scale systems biology of ROS tolerance.

ORGANISM(S): Escherichia coli str. K-12 substr. MG1655

PROVIDER: GSE221314 | GEO | 2022/12/19

REPOSITORIES: GEO

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Project description:A deeper understanding of malaria parasite development inside the Anopheles mosquito may lead to the identification of processes that can be targeted by transmission-blocking interventions. Paraquat (1,1'-dimethyl-4,4'-bipyridylium dichloride) is a potent superoxide-inducing agent that impacts Plasmodium ookinete development, especially at higher concentrations. Compounds like Paraquat can potentially induce an oxidative imbalance in the mosquito midgut during ookinete maturation, essentially super-stressing the parasite leading to the arrested development of ookinetes, the only stage that can invade through a mosquito midgut cell to establish an oocyst infection in the mosquito. The mosquito midgut has evolved to handle the natural production of reactive oxygen and nitrogen species (ROS and RNS, respectively) as a result of feeding on blood. The addition of Paraquat to a bloodmeal is expected to induce a cognate response in the midgut to handle the excess ROS/RNS, and high concentrations of this compound can potentially overwhelm the midgut response leading to mosquito death. While several studies have explored the effect of Paraquat on malaria parasites, a fundamental understanding of the mosquito response to this compound remains unknown. Here, we quantified the mosquito midgut proteomic response to a Paraquat-laced sugar meal to understand the intrinsic midgut response (in the absence of a bloodmeal). We then carried out transcriptomic analysis of the mosquito midgut for several antioxidants of the Trx and GSH pathways to compare concordance or discordance between protein and its transcripts during different oxidative stress conditions. Finally, we determined whether the same Trx and GSH pathways are upregulated following infection with either P. falciparum or P. berghei at 24 hrs post-blood feeding, coinciding with the time point for maximal ookinete traversal of the midgut. We discuss the potential selective action of Paraquat on the parasite and the intrinsic tolerance of the mosquito midgut to Paraquat-mediated oxidative stress.

Project description:Paracoccidioides brasiliensis is a thermodimorphic fungus associated with paracoccidioidomycosis (PCM), the most common systemic mycosis in Latin America. The infection is initiated by inhalation of environmental dispersed conidia produced by the saprophytic phase of the fungus. In the lungs, P. brasiliensis assumes the parasitic yeast form and must cope with the adverse conditions imposed by cells of the host immune system, which includes a harsh environment highly concentrated in reactive oxygen species (ROS). In this work, we used the ROS-generating agent paraquat to experimentally simulate oxidative stress conditions in order to evaluate the stress-induced modulation in gene expression of cultured P. brasiliensis yeast cells using a microarray hybridization approach. Microarray hybridizations were carried out with RNA obtained from cells treated with paraquat (0.5 or 5.0 mM) for 5 hours. The RNA obtained from cells unexposed to paraquat was taken as reference. Each treatment was analyzed with four independent hybridizations (two pairs of dye-swapped hybridizations), using RNA from two biological replicas. The data has been filtered, normalized and adjusted as described in the "data processing" box for each individual sample. Dye swap consistency checking has been performed between equivalent experimental pairs with the aid of the software TIGR MIDAS v2.19 and inconsistent spots have been flagged and excluded from further analyses. The values obtained from each dye swap pair have been averaged and consolidated into a single data file, generating a total of 8 hybridization files (four from each treatment concentration). These files have been loaded into the software TIGR Multi-Experiment Viewer, v.3.01. Experiments were then normalized and genes that displayed statistically significant modulation were identified by one-way ANOVA, considering p < 0.01 as a cutoff value. A list of statisticaly significant, modulated genes was created, showing the average log ratio for each one of these genes, within each time point

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Lab evolution, transcriptomics, and modeling reveal mechanisms of paraquat tolerance

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