Investigation of the Electron Transport Chain to and the Catalytic Activity of the Diheme Cytochrome
            <i>c</i>
            Peroxidase CcpA of Shewanella oneidensis

Schütz, Björn; Seidel, Julian; Sturm, Gunnar; Einsle, Oliver; Gescher, Johannes

doi:10.1128/aem.00606-11

Cited by 53 publications

(67 citation statements)

References 53 publications

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“…Intriguingly, glutathione peroxidase (SO3349 and SO1563), c-type cytochrome peroxidase (CcpA), and organic hydroperoxide resistance protein (Ohr), being OxyR SO dependent or not, are substantially upregulated when stimulated. These proteins function to degrade H 2 O 2 at the expense of NADPH, cytochrome c, and thiol, respectively, although their contribution to H 2 O 2 removal is negligible under the tested aerobic conditions (63)(64)(65). In the case of glutathione peroxidase and Ohr, this is not surprising, given that both proteins are reportedly irrelevant in the bacterial response to H 2 O 2 -induced oxidative stress.…”

Section: Discussionmentioning

confidence: 80%

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Protection from Oxidative Stress Relies Mainly on Derepression of OxyR-Dependent KatB and Dps in Shewanella oneidensis

Jiang¹,

Dong²,

Luo³

et al. 2013

Journal of Bacteriology

172

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Shewanella thrives in redox-stratified environments where accumulation of H 2 O 2 becomes inevitable because of the chemical oxidation of reduced metals, sulfur species, or organic molecules. As a research model, the representative species Shewanella oneidensis has been extensively studied for its response to various stresses. However, little progress has been made toward an understanding of the physiological and genetic responses of this bacterium to oxidative stress, which is critically relevant to its application as a dissimilatory metal-reducing bacterium. In this study, we systematically investigated the mechanism underlying the response to H 2 O 2 at cellular, genomic, and molecular levels. Using transcriptional profiling, we found that S. oneidensis is hypersensitive to H 2 O 2 in comparison with Escherichia coli, and well-conserved defense genes such as ahpCF, katB, katG, and dps appear to form the first line of defense, whereas iron-sulfur-protecting proteins may not play a significant role. Subsequent identification and characterization of an analogue of the E. coli oxyR gene revealed that S. oneidensis OxyR is the master regulator that mediates the bacterial response to H 2 O 2 -induced oxidative stress by directly repressing or activating the defense genes. The sensitivity of S. oneidensis to H 2 O 2 is likely attributable to the lack of an inducible manganese import mechanism during stress. To cope with stress, major strategies that S. oneidensis adopts include rapid removal of the oxidant and restriction of intracellular iron concentrations, both of which are achieved predominantly by derepression of the katB and dps genes.

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Section: Discussionmentioning

confidence: 80%

“…To our knowledge, this is the first time that an Ohr homologue has been found to be responsive to H 2 O 2 (63). Notably, CcpA has been shown to function as a major H 2 O 2 -decomposing enzyme for cells living without oxygen, a condition under which other scavenging proteins may not be produced (65).…”

Section: Discussionmentioning

confidence: 97%

Protection from Oxidative Stress Relies Mainly on Derepression of OxyR-Dependent KatB and Dps in Shewanella oneidensis

Jiang¹,

Dong²,

Luo³

et al. 2013

Journal of Bacteriology

172

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“…6A), showing that additional systems exist for H 2 O 2 removal. Additionally, we assessed the contributions to viability of CcpA and Ohr, two peroxidases that have been implicated in H 2 O 2 scavenging in previous reports (30,45). However, the viabilities of the ⌬katB ⌬ccpA and ⌬katB ⌬ohr strains were indistinguishable from that of the ⌬katB strain under both conditions (Fig.…”

Section: Iron Ions Facilitate Degradation Of H 2 O 2 By Living Cellsmentioning

confidence: 99%

Unraveling the Mechanism for the Viability Deficiency of Shewanella oneidensis oxyR Null Mutant

et al. 2015

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Oxidative stresses triggered by reactive oxygen species (ROS) that damage various cellular components are unavoidable for virtually all living organisms. In defense, microorganisms have evolved sophisticated mechanisms to sense, respond to, and battle against ROS. Shewanella oneidensis, an important research model for applied and environmental microbes, employs OxyR to mediate the response to H 2 O 2 by derepressing the production of the major H 2 O 2 scavenger KatB as a major means toward these goals. Surprisingly, despite enhanced H 2 O 2 degradation, the oxyR mutant carries a viability deficiency phenotype (plating defect), which can be suppressed by the addition of exogenous iron species. Experiments showed that the defect was not due to iron starvation. Rather, multiple lines of evidence suggested that H 2 O 2 generated abiotically in lysogeny broth (LB) is responsible for the defect by quickly killing mutant cells. We then showed that the iron species suppressed the plating defect by two distinct mechanisms, either as an H 2 O 2 scavenger without involving living cells or as an environmental cue to stimulate an OxyR-independent response to help cells cope with oxidative stress. Based on the suppression of the plating defect by overproduction of H 2 O 2 scavengers in vivo, we propose that cellular components that are vulnerable to H 2 O 2 and responsible for the defect may reside outside the cytoplasm. IMPORTANCEIn bacteria, OxyR is the major regulator controlling the cellular response to H 2 O 2 . The loss of OxyR results in reduced viability in many species, but the underlying mechanism is unknown. We showed in S. oneidensis that this defect was due to H 2 O 2 generated abiotically in LB. We then showed that this defect could be corrected by the addition of Fe 2؉ or catalase to the LB or increased intracellular production of catalase. Further analyses revealed that Fe 2؉ was able not only to decompose H 2 O 2 directly but also to stimulate the activity of OxyR-independent H 2 O 2 -scavenging enzymes. Our data indicate that iron species play a previously underappreciated role in protecting cells from H 2 O 2 in environments.

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“…The electron flow occurs through a series of multi-heme cytochromes with overlapping potential windows, to pump electrons from higher potential to lower potential outside the cell. S. oneidensis possess genetic information for 42 distinct c-type cytochromes [52].…”

Section: Set Up Of a Microbial Fuel Cellmentioning

confidence: 99%

Microbial Fuel Cells as Alternate Source of Energy: Research, Advancements and Future Prospects in Indian Scenario

Basheer¹,

Suma²,

Sreelekshmy³

et al. 2017

Asian J. Chem.

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Today, the world is on the verge of transformation from fossil fuels to alternative and sustainable renewable sources due to many reasons. Many plausible technologies have been developed of which, energy from biomass and biowaste is a widely accepted choice. In India too, the fuel crisis is imminent and renewable fuel sources are being developed on a large scale to meet energy requirements. However, generation of electricity from biomass and biowaste is a rather unconventional method which is less exploited. The technology that possesses immense future prospective requires collaboration of expertise from various disciplines of science. Here we present a comprehensive view of developments and novel approaches in microbial fuel cell research in Indian scenario in the backdrop of the developments on a global scale. Though the research outputs in India in terms of power density is in par with that on global scale, we lag behind in bringing a collaborative approach.

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Investigation of the Electron Transport Chain to and the Catalytic Activity of the Diheme Cytochrome c Peroxidase CcpA of Shewanella oneidensis

Cited by 53 publications

References 53 publications

Protection from Oxidative Stress Relies Mainly on Derepression of OxyR-Dependent KatB and Dps in Shewanella oneidensis

Protection from Oxidative Stress Relies Mainly on Derepression of OxyR-Dependent KatB and Dps in Shewanella oneidensis

Unraveling the Mechanism for the Viability Deficiency of Shewanella oneidensis oxyR Null Mutant

Microbial Fuel Cells as Alternate Source of Energy: Research, Advancements and Future Prospects in Indian Scenario

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