ASalmonella entericaSerovar TyphimuriumhemAMutant Is Highly Susceptible to Oxidative DNA Damage

Elgrably‐Weiss, Maya; Park, Sunny; Schlosser-Silverman, Eliana; Rosenshine, Ilan; Imlay, James A.; Altuvia, Shoshy

doi:10.1128/jb.184.14.3774-3784.2002

Cited by 35 publications

(33 citation statements)

References 41 publications

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“…Primer extension assays were carried out as described previously (10). Briefly, bacterial cultures grown to an OD 600 of 0.3 or 1.0 were pelleted and resuspended in 10 mM Tris, pH 7.5, and 1 mM EDTA.…”

Section: Methodsmentioning

confidence: 99%

Identification of an Escherichia coli Operon Required for Formation of the O-Antigen Capsule

et al. 2005

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Escherichia coli produces polysaccharide capsules that, based on their mechanisms of synthesis and assembly, have been classified into four groups. The group 4 capsule (G4C) polysaccharide is frequently identical to that of the cognate lipopolysaccharide O side chain and has, therefore, also been termed the O-antigen capsule. The genes involved in the assembly of the group 1, 2, and 3 capsules have been described, but those required for G4C assembly remained obscure. We found that enteropathogenic E. coli (EPEC) produces G4C, and we identified an operon containing seven genes, ymcD, ymcC, ymcB, ymcA, yccZ, etp, and etk, which are required for formation of the capsule. The encoded proteins appear to constitute a polysaccharide secretion system. The G4C operon is absent from the genomes of enteroaggregative E. coli and uropathogenic E. coli. E. coli K-12 contains the G4C operon but does not express it, because of the presence of IS1 at its promoter region. In contrast, EPEC, enterohemorrhagic E. coli, and Shigella species possess an intact G4C operon.

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Section: Methodsmentioning

confidence: 99%

Identification of an Escherichia coli Operon Required for Formation of the O-Antigen Capsule

et al. 2005

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“…The simplest explanation for these data is that the hemA mutant produces or acquires enough heme to synthesize KatG, albeit in lesser quantity than the wild type, and that this amount is sufficient to degrade H 2 O 2 produced by aerobic metabolism. Earlier studies showed that a ␦-aminolevulinic acid synthesis mutant of Salmonella is susceptible to oxidative stress (8) and that heme synthesis genes in E. coli are induced by H 2 O 2 (46). In those studies, oxidative stress responses were assessed by exposure to exogenous H 2 O 2 .…”

Section: Fig 2 Arrangements Of Katg Oxyr Ahpc and Ahpd In The Bmentioning

confidence: 99%

“…This induction is coordinated with the activation of catalase-encoding genes by OxyR in E. coli and Salmonella serovar Typhimurium and by PerR in Bacillus subtilis. A serovar Typhimurium heme biosynthesis mutant displays increased sensitivity to killing by H 2 O 2 , but this finding was attributed to an accumulation of reducing equivalents to drive the Fenton reaction rather than to a catalase deficiency alone (8).…”

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confidence: 99%

“…Thus, Ahp is the primary scavenger of endogenous H 2 O 2 in E. coli, and catalase activity becomes essential only when the H 2 O 2 concentration is high. Exposure to H 2 O 2 induces heme biosynthesis genes in E. coli (46), Salmonella enterica serovar Typhimurium (8), and Bacillus subtilis (5,20), presumably because catalases are heme proteins. This induction is coordinated with the activation of catalase-encoding genes by OxyR in E. coli and Salmonella serovar Typhimurium and by PerR in Bacillus subtilis.…”

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confidence: 99%

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KatG Is the Primary Detoxifier of Hydrogen Peroxide Produced by Aerobic Metabolism in Bradyrhizobium japonicum

Panek

O’Brian

2004

J Bacteriol

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Bacteria are exposed to reactive oxygen species from the environment and from those generated by aerobic metabolism. Catalases are heme proteins that detoxify H 2 O 2 , and many bacteria contain more than one catalase enzyme. Also, the nonheme peroxidase alkyl hydroperoxide reductase (Ahp) is the major scavenger of endogenous H 2 O 2 in Escherichia coli. Here, we show that aerobically grown Bradyrhizobium japonicum cells express a single catalase activity. Four genes encoding putative catalases in the B. japonicum genome were identified, including a katG homolog encoding a catalase-peroxidase. Deletion of the katG gene resulted in loss of catalase activity in cell extracts and of exogenous H 2 O 2 consumption by whole cells. The katG strain had a severe aerobic growth phenotype but showed improved growth in the absence of O 2 . By contrast, a B. japonicum ahpCD mutant grew well aerobically and consumed H 2 O 2 at wild-type rates. A heme-deficient hemA mutant expressed about one-third of the KatG activity as the wild type but grew well aerobically and scavenged low concentrations of exogenous H 2 O 2 . However, cells of the hemA strain were deficient in consumption of high concentrations of H 2 O 2 and were very sensitive to killing by short exposure to H 2 O 2 . In addition, KatG activity did not decrease as a result of mutation of the gene encoding the transcriptional activator OxyR. We conclude that aerobic metabolism produces toxic levels of H 2 O 2 in B. japonicum, which is detoxified primarily by KatG. Furthermore, the katG level sufficient for detoxification does not require OxyR.

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“…DNA synthesis (EdU incorporation) seems to be sensitive to oxidative stress, 37) and our results (Figs. 6-8) also showed sensitivity of Salmonella to H 2 O 2 in this regard.…”

Section: Discussionmentioning

confidence: 57%

Use of Flow Cytometry for Quantitative Analysis of Metabolism of Viable but Non-culturable (VBNC) Salmonella

Morishige

Fujimori

Amano

2015

Biological & Pharmaceutical Bulletin

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A simple and rapid assay method for analysis of the metabolic activity of viable but non-culturable (VBNC) Salmonella was established. An environmental isolate of Salmonella Enteritidis (SE), grown to the logarithmic phase, rapidly lost its culturability during incubation with 1-10 mM H 2 O 2 in Luria-Bertani (LB) medium. To assess the viability of the bacteria, we measured 3 different metabolic activities: Respiratory activity by 5-cyano-2,3-ditolyl-tetrazolium chloride (CTC) reduction, glucose uptake assessed with 2-[N-(7-nitrobenz-2-oxa-1,3-diazol-4-yl)amino]-2-deoxyglucose (2-NBDG), and DNA synthesis activity evaluated by 5-ethynyl-2′-deoxyuridine (EdU) incorporation. These activities were analyzed by both confocal laser-scanning microscopy and flow cytometry, together with colony-formation assays on LB-agar plates. The results showed that some of the H 2 O 2 -treated SE cells were in the VBNC state and that the extent of H 2 O 2 -induced decrease in each metabolic activity varied according to the activity. That is, glucose-uptake activity was not markedly changed, being kept at the highest level; whereas the respiratory activity was less than that of the glucose-uptake, and DNA synthesis activity was the lowest among them. These results suggest that the VBNC state might be characterized by different metabolic activities that vary and correspond to the kind and strength of the stress, threatening bacterial survival in an adverse environment.

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ASalmonella entericaSerovar TyphimuriumhemAMutant Is Highly Susceptible to Oxidative DNA Damage

Cited by 35 publications

References 41 publications

Identification of an Escherichia coli Operon Required for Formation of the O-Antigen Capsule

Identification of an Escherichia coli Operon Required for Formation of the O-Antigen Capsule

KatG Is the Primary Detoxifier of Hydrogen Peroxide Produced by Aerobic Metabolism in Bradyrhizobium japonicum

Use of Flow Cytometry for Quantitative Analysis of Metabolism of Viable but Non-culturable (VBNC) <i>Salmonella</i>

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