<scp><scp>Crp</scp></scp>‐dependent cytochrome <i>bd</i> oxidase confers nitrite resistance to <i><scp>S</scp>hewanella oneidensis</i>

Fu, Huihui; Chen, Haijiang; Wang, Jixuan; Zhou, Guangqi; Zhang, Haiyan; Zhang, Lili; Gao, Haichun

doi:10.1111/1462-2920.12091

Cited by 80 publications

(185 citation statements)

References 62 publications

(170 reference statements)

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“…We have previously shown that S. oneidensis prefers insoluble to soluble electron acceptors for respiration, such as Fe (III) oxide versus oxygen, thus preventing endogenous generation of ROS from autoxidation of components of the respiratory chain (35,59). In addition, unlike other organisms containing cytochrome caa 3 -type and cbb 3 -type oxidases, where the low-affinity (caa 3 -type) oxidase plays a dominant role under high-oxygen conditions and the cbb 3 oxidase is induced only at low O 2 concentrations, S. oneidensis utilizes the cbb 3 -type oxidase under both high-and low-oxygen conditions and does not express the caa 3 oxidase (39,40). As respiration of oxygen by the cbb 3 oxidase is relatively slow, less ROS would be generated.…”

Section: Discussionmentioning

confidence: 88%

A Matter of Timing: Contrasting Effects of Hydrogen Sulfide on Oxidative Stress Response in Shewanella oneidensis

Wan

et al. 2015

J Bacteriol

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Hydrogen sulfide (H 2 S), well known for its toxic properties, has recently become a research focus in bacteria, in part because it has been found to prevent oxidative stress caused by treatment with some antibiotics. H 2 S has the ability to scavenge reactive oxygen species (ROS), thus preventing oxidative stress, but it is also toxic, leading to conflicting reports of its effects in different organisms. Here, with Shewanella oneidensis as a model, we report that the effects of H 2 S on the response to oxidative stress are time dependent. When added simultaneously with H 2 O 2 , H 2 S promoted H 2 O 2 toxicity by inactivating catalase, KatB, a hemecontaining enzyme involved in H 2 O 2 degradation. Such an inhibitory effect may apply to other heme-containing proteins, such as cytochrome cbb 3 oxidase. When H 2 O 2 was supplied 20 min or later after the addition of H 2 S, the oxidative-stress-responding regulator OxyR was activated, resulting in increased resistance to H 2 O 2 . The activation of OxyR was likely triggered by the influx of iron, a response to lowered intracellular iron due to the iron-sequestering property of H 2 S. Given that Shewanella bacteria thrive in redox-stratified environments that have abundant sulfur and iron species, our results imply that H 2 S is more important for bacterial survival in such environmental niches than previously believed. IMPORTANCE Previous studies have demonstrated that H 2 S is either detrimental or beneficial to bacterial cells. While it can act as a growth-inhibiting molecule by damaging DNA and denaturing proteins, it helps cells to combat oxidative stress. Here we report that H 2 S indeed has these contrasting biological functions and that its effects are time dependent. Immediately after H 2 S treatment, there is growth inhibition due to damage of heme-containing proteins, at least to catalase and cytochrome c oxidase. In contrast, when added a certain time later, H 2 S confers an enhanced ability to combat oxidative stress by activating the H 2 O 2 -responding regulator OxyR. Our data reconcile conflicting observations about the functions of H 2 S.

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Section: Discussionmentioning

confidence: 88%

A Matter of Timing: Contrasting Effects of Hydrogen Sulfide on Oxidative Stress Response in Shewanella oneidensis

Wan

et al. 2015

J Bacteriol

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“…To detect an interaction, vectors containing "bait" (DNA) and "target" (DNA-binding regulator) are cotransformed into BacterioMatch II Validation Reporter competent cells, of which those having positive DNA-protein interactions are able to grow on 3-amino-1,2,4-triazole (3-AT). To calibrate this system, we took advantage of S. oneidensis Crp, which was shown previously to bind to motif sequences upstream of the cyd operon (cytochrome bd oxidase) (55,56). The crp SO gene was cloned into the target vector pTRG, and the cyd promoter containing the Crp SObinding motif was generated by PCR and inserted into the reporter vector pBXcmT.…”

Section: Resultsmentioning

confidence: 99%

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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“…6), because it has been established that mutation rates increase exponentially with increasing numbers of repeat units (35). The copy number of pHG101, which is based on the RK2 replicon, is about 4 to 7 per cell in E. coli and is estimated to be in a similar range in S. oneidensis (26,36). Clearly, the double mutant carrying the TR-containing fragments F1, F3, and F4 became hypermutable ( Fig.…”

Section: Resultsmentioning

confidence: 99%

“…The resultant vectors were then verified by sequencing and transferred into relevant strains by conjugation. To eliminate the antibiotic marker, helper plasmid pBBR-Cre was transferred into the strains carrying a correctly integrated construct (26). Midlog phase cultures were harvested, aliquoted, and subjected to ␤-galactosidase activity assays as described before (25).…”

Section: Methodsmentioning

confidence: 99%

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Suppression of fabB Mutation by fabF1 Is Mediated by Transcription Read-through in Shewanella oneidensis

Quanfei

et al. 2016

J Bacteriol

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As type II fatty acid synthesis is essential for the growth of Escherichia coli, its many components are regarded as potential targets for novel antibacterial drugs. Among them, ␤-ketoacyl-acyl carrier protein (ACP) synthase (KAS) FabB is the exclusive factor for elongation of the cis-3-decenoyl-ACP (cis-3-C 10 -ACP). In our previous study, we presented evidence to suggest that this may not be the case in Shewanella oneidensis, an emerging model gammaproteobacterium renowned for its respiratory versatility. Here, we identified FabF1, another KAS, as a functional replacement for FabB in S. oneidensis. In fabB ؉ or desA ؉ (encoding a desaturase) cells, which are capable of making unsaturated fatty acids (UFA), FabF1 is barely produced. However, UFA auxotroph mutants devoid of both fabB and desA genes can be spontaneously converted to suppressor strains, which no longer require exogenous UFAs for growth. Suppression is caused by a TGTTTT deletion in the region upstream of the fabF1 gene, resulting in enhanced FabF1 production. We further demonstrated that the deletion leads to transcription read-through of the terminator for acpP, an acyl carrier protein gene immediately upstream of fabF1. There are multiple tandem repeats in the region covering the terminator, and the TGTTTT deletion, as well as others, compromises the terminator efficacy. In addition, FabF2 also shows an ability to complement the FabB loss, albeit substantially less effectively than FabF1. IMPORTANCEIt has been firmly established that FabB for UFA synthesis via type II fatty acid synthesis in FabA-containing bacteria such as E. coli is essential. However, S. oneidensis appears to be an exception. In this bacterium, FabF1, when sufficiently expressed, is able to fully complement the FabB loss. Importantly, such a capability can be obtained by spontaneous mutations, which lead to transcription read-through. Therefore, our data, by identifying the functional overlap between FabB and FabFs, provide new insights into the current understanding of KAS and help reveal novel ways to block UFA synthesis for therapeutic purposes. The de novo fatty acid synthesis (FAS) pathway, namely, type II, is the predominant, if not exclusive, route for endogenous production of fatty acids (1). The FAS pathway, the current knowledge of which derives mainly from the model organism Escherichia coli, is highly conserved in bacteria. Central to the pathway are reactions catalyzed by ␤-ketoacyl-acyl carrier protein (ACP) synthases (KAS), including FabH, FabB, and FabF. FabH is responsible for the condensation of an acyl coenzyme A (acylCoA) unit and a malonyl-acyl carrier protein (malonyl-ACP) unit, but cannot work with acetyl-ACP, the substrate of FabB and FabF; as a consequence, FabH could not function as a replacement for FabB or FabF (1). While FabB and FabF are exchangeable in elongation of saturated intermediates, each catalyzes a reaction with the unsaturated branch that the other cannot or at least much less effectively (2) (Fig. 1). The key reaction catalyze...

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Crp‐dependent cytochrome bd oxidase confers nitrite resistance to Shewanella oneidensis

Cited by 80 publications

References 62 publications

A Matter of Timing: Contrasting Effects of Hydrogen Sulfide on Oxidative Stress Response in Shewanella oneidensis

A Matter of Timing: Contrasting Effects of Hydrogen Sulfide on Oxidative Stress Response in Shewanella oneidensis

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

Suppression of fabB Mutation by fabF1 Is Mediated by Transcription Read-through in Shewanella oneidensis

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