Metabolic Interference of sod gene mutations on catalase activity in Escherichia coli exposed to Gramoxone® (paraquat) herbicide

Flavodoxins are small electron transfer proteins containing flavin mononucleotide (FMN) as a prosthetic group, which play an important role during oxidative stress or iron limitation. The aims of this study were the identification and characterization of flavodoxins in the model aromatic-degrader Paraburkholderia xenovorans LB400 and the analyses of their protective effects during oxidative stress induced by paraquat and H 2 O 2 . Two genes (BxeA0278 and BxeB0391) encoding flavodoxins (hereafter referred to as fldX for fl avo d oxin from P . x enovorans ), were identified at the LB400 major and minor chromosome. Genomic context of the flavodoxin-encoding genes showed genes encoding membrane proteins, transporters, and proteins involved in redox processes and biosynthesis of macromolecules. A secondary structure prediction of both LB400 flavodoxins showed the characteristic flavodoxin structure of five ß-sheets intercalated with five α-helices. FldX1 contains a loop intercalated in the fifth β-strand, which indicates that it belongs to the long-chain flavodoxins, whereas FldX2 is a short-chain flavodoxin. A phylogenetic analysis of 73 flavodoxins from 43 bacterial genera revealed eight clusters (I-VIII), while FldX1 and FldX2 grouped separately within a long-chain and a short-chain flavodoxin clades. FldX1 and FldX2 were overexpressed in P . xenovorans . Interestingly, the strain overexpressing the long-chain flavodoxin FldX1 (p2-fldX1) showed a faster growth in glucose than the control strain. The recombinant strain overexpressing the long-chain flavodoxin FldX1 (p2- fldx1 ) exposed to paraquat (20 mM) possessed lower susceptibility to growth inhibition on plates and higher survival in liquid medium than the control strain. The strains overexpressing the flavodoxins FldX1 and FldX2 showed higher survival during exposure to 1 mM paraquat (>95%) than the control strain (68%). Compared to the control strain, strains overexpressing FldX1 and FldX2 showed lower lipid peroxidation (>20%) after exposure to 1 mM paraquat and a lower protein carbonylation (~30%) after exposure to 1 mM H 2 O 2 was observed. During exposure to paraquat, strain p2- fldx1 downregulated the katG4 , hpf , trxB1 and ohr genes (> 2-fold), whereas strain p2- fldx2 upregulated the oxyR and ahpC1 genes (> 2-fold). In conclusion, the flavodoxins FldX1 and FldX2 of P . xenovorans LB400 conferred protection to cells exposed to the oxidizing agents paraquat and H 2 O ...

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“…M3004 and E . coli K-12 [49,50]. The redox-cycling compound paraquat generates O 2 - that is dismuted into H 2 O 2 .…”

Section: Discussionmentioning

confidence: 99%

Long-chain flavodoxin FldX1 improves Paraburkholderia xenovorans LB400 tolerance to oxidative stress caused by paraquat and H2O2

et al. 2019

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“…Other herbicides have this characteristic of increasing the amount of H 2 O 2 in two strains of Bacillus megaterium, leading to the combined toxic effects of adjuvants and the active molecule mesotrione (Dobrzanski et al, 2018). In the same way, the herbicide gramoxone was seen to cause this effect in strains of Escherichia coli (Gravina et al, 2017).…”

Section: Quantification Of H 2 Omentioning

confidence: 94%

Herbicides Tolerance in a Pseudomonas Strain Is Associated With Metabolic Plasticity of Antioxidative Enzymes Regardless of Selection

et al. 2021

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Agriculture uses many food production chains, and herbicides participate in this process by eliminating weeds through different biochemical strategies. However, herbicides can affect non-target organisms such as bacteria, which can suffer damage if there is no efficient control of reactive oxygen species. It is not clear, according to the literature, whether the efficiency of this control needs to be selected by the presence of xenobiotics. Thus, the Pseudomonas sp. CMA 6.9 strain, collected from biofilms in an herbicide packaging washing tank, was selected for its tolerance to pesticides and analyzed for activities of different antioxidative enzymes against the herbicides Boral®, absent at the isolation site, and Heat®, present at the site; both herbicides have the same mode of action, the inhibition of the enzyme protoporphyrinogen oxidase. The strain showed tolerance to both herbicides in doses up to 45 times than those applied in agriculture. The toxicity of these herbicides, which is greater for Boral®, was assessed by means of oxidative stress indicators, growth kinetics, viability, and amounts of peroxide and malondialdehyde. However, the studied strain showed two characteristic antioxidant response systems for each herbicide: glutathione-s-transferase acting to control malondialdehyde in treatments with Boral®; and catalase, ascorbate peroxidase, and guaiacol peroxidase in the control of peroxide induced by Heat®. It is possible that this modulation of the activity of different enzymes independent of previous selection characterizes a system of metabolic plasticity that may be more general in the adaptation of microorganisms in soil and water environments subjected to chemical contaminants. This is relevant to the impact of pesticides on the diversity and abundance of microbial species as well as a promising line of metabolic studies in microbial consortia for use in bioremediation.

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“…Hydrogen peroxide was quantified in a spectrophotometer at 390 nm by the iodine release method as previously described by Gravina et al [ 11 ]. Protein extracts were obtained by the maceration of bacterial pellets in liquid nitrogen followed by homogenization in 1 mL of 0.1% TCA, and centrifuged at 8,000 × g for 15 min at 4 °C.…”

Section: Methodsmentioning

confidence: 99%

“…Reactions were incubated for 1 h on ice in the dark. The results were expressed in μmol/g of fresh weight [ 11 ].…”

Section: Methodsmentioning

confidence: 99%

“…Tolerant and/or degrading microorganisms may have distinct metabolic responses when exposed to herbicides, including an increased generation of reactive oxygen species (ROS) [ 9 , 10 , 11 ]. ROS, such as superoxide (O 2 - ), hydrogen peroxide (H 2 O 2 ), and the hydroxyl radical ● OH, are generated continuously in cells under aerobic conditions [ 12 , 13 ].…”

Section: Introductionmentioning

confidence: 99%

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Bacillus megaterium strains derived from water and soil exhibit differential responses to the herbicide mesotrione

Dobrzanski¹,

Gravina²,

Steckling³

et al. 2018

PLoS ONE

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The intense use of herbicides for weed control in agriculture causes selection pressure on soil microbiota and water ecosystems, possibly resulting in changes to microbial processes, such as biogeochemical cycles. These xenobiotics may increase the production of reactive oxygen species and consequently affect the survival of microorganisms, which need to develop strategies to adapt to these conditions and maintain their ecological functionality. This study analyzed the adaptive responses of bacterial isolates belonging to the same species, originating from two different environments (water and soil), and subjected to selection pressure by herbicides. The effects of herbicide Callisto and its active ingredient, mesotrione, induced different adaptation strategies on the cellular, enzymatic, and structural systems of two Bacillus megaterium isolates obtained from these environments. The lipid saturation patterns observed may have affected membrane permeability in response to this herbicide. Moreover, this may have led to different levels of responses involving superoxide dismutase and catalase activities, and enzyme polymorphisms. Due to these response systems, the strain isolated from water exhibited higher growth rates than did the soil strain, in evaluations made in oligotrophic culture media, which would be more like that found in semi-pristine aquatic environments. The influence of the intracellular oxidizing environments, which changed the mode of degradation of mesotrione in our experimental model and produced different metabolites, can also be observed in soil and water at sites related to agriculture. Since the different metabolites may present different levels of toxicity, we suggest that this fact should be considered in studies on the fate of agrochemicals in different environments.

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Metabolic Interference of sod gene mutations on catalase activity in Escherichia coli exposed to Gramoxone® (paraquat) herbicide

Cited by 16 publications

References 58 publications

Long-chain flavodoxin FldX1 improves Paraburkholderia xenovorans LB400 tolerance to oxidative stress caused by paraquat and H2O2

Long-chain flavodoxin FldX1 improves Paraburkholderia xenovorans LB400 tolerance to oxidative stress caused by paraquat and H2O2

Herbicides Tolerance in a Pseudomonas Strain Is Associated With Metabolic Plasticity of Antioxidative Enzymes Regardless of Selection

Bacillus megaterium strains derived from water and soil exhibit differential responses to the herbicide mesotrione

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