Bacteria form intracellular free radicals in response to paraquat and streptonigrin. Demonstration of the potency of hydroxyl radical.

Hassett, Daniel J.; Britigan, B. E.; Svendsen, T.; Rosen, Gerald M.; Cohen, Myron S.

doi:10.1016/s0021-9258(19)76440-0

Cited by 76 publications

(9 citation statements)

References 45 publications

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“…Exposure of cells to menadione is commonly employed to study the effects of intracellular O # d − and H # O # formation [4][5][6][7][8][9]. Using a fluorescence-based assay with the Ca# + -sensitive probe fura 2, we found that exposure of the human alveolar type-II cell line A549 to menadione resulted in a rapid rise in [Ca# + ] i , which was the result of an influx of extracellular Ca# + .…”

Section: Discussionmentioning

confidence: 99%

“…The cellular consequences of oxidant exposure, as well as the relative importance of different cellular antioxidant systems in protecting cells from such exposures, varies with both the nature of the oxidant species generated and the intracellular and\or extracellular location of generation [2,3]. To study in itro the effects of increased cellular exposure to O # d − and H # O # , investigators have employed a variety of redox-active compounds such as menadione, methyl viologen (paraquat), pyocyanine and streptonigrin [4][5][6][7]. Each of these compounds can undergo cellmediated one-electron reduction, with subsequent electron transfer to oxygen, generating O # d − and H # O # [4][5][6][7][8][9].…”

Section: Introductionmentioning

confidence: 99%

“…To study in itro the effects of increased cellular exposure to O # d − and H # O # , investigators have employed a variety of redox-active compounds such as menadione, methyl viologen (paraquat), pyocyanine and streptonigrin [4][5][6][7]. Each of these compounds can undergo cellmediated one-electron reduction, with subsequent electron transfer to oxygen, generating O # d − and H # O # [4][5][6][7][8][9]. Among the effects resulting from cellular oxidant exposure is a rise in intracellular Ca# + ([Ca# + ] i ) [10][11][12][13][14][15].…”

Section: Introductionmentioning

confidence: 99%

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Biological effects of menadione photochemistry: effects of menadione on biological systems may not involve classical oxidant production

et al. 2000

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Because cell-mediated reduction of menadione leads to the generation of reactive oxygen species (ROS), this quinone is widely used to investigate the effects of ROS on cellular functions. We report that A549 human lung epithelial cells exposed to menadione demonstrate a dose-dependent increase in both intracellular calcium ([Ca(2+)](i)) and ROS formation. The concentrations of menadione required to initiate these two events are markedly different, with ROS detection requiring higher levels of menadione. Modulators of antioxidant defences (e.g. buthionine sulphoximine, 3-amino-1,2,4-triazole) have little effect on the [Ca(2+)](i) response to menadione, suggesting that ROS formation does not account for menadione-dependent alterations in [Ca(2+)](i). Additional evidence suggests that menadione photochemistry may be responsible for the observed [Ca(2+)](i) effects. Specifically: (a) EPR studies with the spin trap 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) show that light exposure (maximum effect at 340 nm) stimulates menadione-dependent formation of the DMPO/(.)OH spin adduct that was not sensitive to antioxidant interventions; (b) DMPO inhibits menadione and light-dependent increases in [Ca(2+)](i); and (c) light (maximum effect at 340 nm) augments the deleterious effects of menadione on cell viability as determined by (51)Cr release. These photo effects do not appear to involve formation of singlet oxygen by menadione, but rather are the result of the oxidizing chemistry initiated by menadione in the triplet state. This work demonstrates that menadione species generated by photo-irradiation can exert biological effects on cellular functions and points to the potential importance of photochemistry in studies of menadione-mediated cell damage.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Biological effects of menadione photochemistry: effects of menadione on biological systems may not involve classical oxidant production

et al. 2000

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“…During the respiratory burst of the phagocyte, a membrane-bound NADPH oxidase reduces molecular oxygen by one electron to superoxide (02 ) (2). Previous studies have shown that N. gonorrhoeae is highly resistant to extracellular 2-(1) probably because exogenous 02cannot traverse bacterial membranes (8). However, within acidic environments (such as neutrophils), 02spontaneously disproportionates to a stronger oxidant, hydrogen peroxide (H202).…”

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confidence: 99%

Variation in hydrogen peroxide sensitivity between different strains of Neisseria gonorrhoeae is dependent on factors in addition to catalase activity

et al. 1994

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Catalase, which catalyzes the reduction of hydrogen peroxide to oxygen and water, is considered the primary defense of Neisseria gonorrhoeae against exogenous hydrogen peroxide. Recent reports have demonstrated drastically different sensitivities of the organism to hydrogen peroxide ranging from greater than 80% survival after challenge with 30 mM hydrogen peroxide to less than 0.001% survival after challenge with 10 mM hydrogen peroxide. In this study, we have examined the hydrogen peroxide sensitivities of six clinical gonococcal isolates. The study demonstrates that the variations in gonococcal hydrogen peroxide sensitivities previously reported can be attributed to (i) differences in experimental methods employed or (ii) variation among different gonococcal strains. All of the gonococcal isolates examined generated similar concentrations of catalase, implying that the differences in the H2O2 sensitivity observed may depend on factors in addition to catalase.

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“…We measured available iron levels using a streptonigrin (SNG) sensitivity assay (Justino et al, 2007;Nachin et al, 2001), because SNG killing is linked to the intracellular formation of oxygen radicals in the presence of iron (Hassett et al, 1987;Yeowell and White, 1982). Growth of the Δfur and Δfur ΔsspB strains was almost completely inhibited by 0.25 μg/ml SNG, while NA1000 was only mildly inhibited (Fig.…”

Section: Lipid A-deficient Caulobacter Mutants Produce a Three-layer Cell Envelopementioning

confidence: 99%

Caulobacter requires anionic sphingolipids and deactivation of fur to lose lipid A

Zik

Yoon

Guan

et al. 2022

Preprint

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Lipid A, the membrane-anchored portion of lipopolysaccharide, is an essential component of the outer membrane (OM) of nearly all Gram-negative bacteria. Here, we identify regulatory and structural factors that together permit Caulobacter crescentus to eliminate lipid A from its OM. Mutations in the ferric uptake regulator fur allow Caulobacter to survive in the absence of either LpxC, which catalyzes an early step of lipid A synthesis, or CtpA, a tyrosine phosphatase homolog which we find is needed for wild-type lipid A structure and abundance. Alterations in Fur-regulated processes, rather than iron status per se, underlie the ability to eliminate lipid A. Fitness of lipid A-deficient Caulobacter requires a previously uncharacterized anionic sphingolipid, ceramide phosphoglycerate (CPG), which also mediates sensitivity to the antibiotic colistin. Our results demonstrate that, in an altered regulatory landscape, anionic sphingolipids can support the integrity of a lipid A-deficient OM.

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Bacteria form intracellular free radicals in response to paraquat and streptonigrin. Demonstration of the potency of hydroxyl radical.

Cited by 76 publications

References 45 publications

Biological effects of menadione photochemistry: effects of menadione on biological systems may not involve classical oxidant production

Biological effects of menadione photochemistry: effects of menadione on biological systems may not involve classical oxidant production

Variation in hydrogen peroxide sensitivity between different strains of Neisseria gonorrhoeae is dependent on factors in addition to catalase activity

Caulobacter requires anionic sphingolipids and deactivation of fur to lose lipid A

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