The inactivation of dihydroxy-acid dehydratase in Escherichia coli treated with hyperbaric oxygen occurs because of the destruction of its Fe-S cluster, but the enzyme remains in the cell in a form that can be reactivated.

Flint, Dennis H.; Smyk-Randall, Elzbieta M.; Tuminello, J.F.; Draczynska-Lusiak, B; Brown, Olen R.

doi:10.1016/s0021-9258(19)74426-3

Cited by 103 publications

(30 citation statements)

References 25 publications

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“…1). Subsequent in vitro experiments demonstrated that tellurite-mediated FumA inactivation involves Fe 2+ release from the enzyme, a common feature observed in ROS-damaged [4Fe-4S] clusters (Flint et al, 1993a, b;Imlay, 2003).…”

Section: Discussionmentioning

confidence: 98%

Tellurite-mediated disabling of [4Fe–4S] clusters of Escherichia coli dehydratases

et al. 2009

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The tellurium oxyanion tellurite is toxic for most organisms and it seems to alter a number of intracellular targets. In this work the toxic effects of tellurite upon Escherichia coli [4Fe-4S] cluster-containing dehydratases was studied. Reactive oxygen species (ROS)-sensitive fumarase A (FumA) and aconitase B (AcnB) as well as ROS-resistant fumarase C (FumC) and aconitase A (AcnA) were assayed in cell-free extracts from tellurite-exposed cells in both the presence and absence of oxygen. While over 90 % of FumA and AcnB activities were lost in the presence of oxygen, no enzyme inactivation was observed in anaerobiosis. This result was not dependent upon protein biosynthesis, as determined using translation-arrested cells. Enzyme activity of purified FumA and AcnB was inhibited when exposed to an in vitro superoxide-generating, telluritereducing system (ITRS). No inhibitory effect was observed when tellurite was omitted from the ITRS. In vivo and in vitro reconstitution experiments with tellurite-damaged FumA and AcnB suggested that tellurite effects involve [Fe-S] cluster disabling. In fact, after exposing FumA to ITRS, released ferrous ion from the enzyme was demonstrated by spectroscopic analysis using the specific Fe 2+ chelator 2,29-bipyridyl. Subsequent spectroscopic paramagnetic resonance analysis of FumA exposed to ITRS showed the characteristic signal of an oxidatively inactivated [3Fe-4S] + cluster. These results suggest that tellurite inactivates enzymes of this kind via a superoxide-dependent disabling of their [4Fe-4S] catalytic clusters.

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Section: Discussionmentioning

confidence: 98%

Tellurite-mediated disabling of [4Fe–4S] clusters of Escherichia coli dehydratases

et al. 2009

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“…These reactions are one source of the protein carbonylation that can be detected in H 2 O 2 -stressed cells (13). The branched-chain biosynthetic defects as well as the TCAcycle defects are caused by the oxidation of the [4Fe-4S] clusters of dehydratase enzymes (20,(22)(23)(24)(25)(26). A solvent-exposed iron atom of these clusters binds substrate directly, activating it for deprotonation and subsequently completing the dehydration by abstracting a hydroxide anion.…”

Section: The Classes Of Damage Caused By Superoxide and Hydrogen Peroxidementioning

confidence: 99%

How Microbes Defend Themselves From Incoming Hydrogen Peroxide

Sen

Imlay

2021

Front. Immunol.

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Microbes rely upon iron as a cofactor for many enzymes in their central metabolic processes. The reactive oxygen species (ROS) superoxide and hydrogen peroxide react rapidly with iron, and inside cells they can generate both enzyme and DNA damage. ROS are formed in some bacterial habitats by abiotic processes. The vulnerability of bacteria to ROS is also apparently exploited by ROS-generating host defense systems and bacterial competitors. Phagocyte-derived O2− can toxify captured bacteria by damaging unidentified biomolecules on the cell surface; it is unclear whether phagocytic H2O2, which can penetrate into the cell interior, also plays a role in suppressing bacterial invasion. Both pathogenic and free-living microbes activate defensive strategies to defend themselves against incoming H2O2. Most bacteria sense the H2O2via OxyR or PerR transcription factors, whereas yeast uses the Grx3/Yap1 system. In general these regulators induce enzymes that reduce cytoplasmic H2O2 concentrations, decrease the intracellular iron pools, and repair the H2O2-mediated damage. However, individual organisms have tailored these transcription factors and their regulons to suit their particular environmental niches. Some bacteria even contain both OxyR and PerR, raising the question as to why they need both systems. In lab experiments these regulators can also respond to nitric oxide and disulfide stress, although it is unclear whether the responses are physiologically relevant. The next step is to extend these studies to natural environments, so that we can better understand the circumstances in which these systems act. In particular, it is important to probe the role they may play in enabling host infection by microbial pathogens.

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“…, those from Escherichia coli (EcDHAD), Mycobacterium tuberculosis (MbDHAD), Sulfolobus solfataricus (SsDHAD), and Arabidopsis thaliana (AtDHAD). Together, these studies establish DHAD as a member of the IlvD/EDD protein family with a [2Fe-2S] or [4Fe-4S] cluster, which generally leads to the enzyme being oxygen sensitive . In addition, the structural basis of DHAD catalysis was revealed only recently in the studies of AtDHAD and MbDHAD .…”

Section: Introductionmentioning

confidence: 99%

“…Together, these studies establish DHAD as a member of the IlvD/EDD protein family with a [2Fe-2S] or [4Fe-4S] cluster, which generally leads to the enzyme being oxygen sensitive. 17 In addition, the structural basis of DHAD catalysis was revealed only recently in the studies of AtDHAD 25 and MbDHAD. 18 Notably, AtDHAD and MbDHAD, which both contain a [2Fe-2S] cluster, are inhibited to varying degrees by the natural product aspterric acid (AA).…”

Section: ■ Introductionmentioning

confidence: 99%

“…KIV is the precursor of both l -Leu and pantothenate, an intermediate to the essential cofactor coenzyme A . To date, nine DHADs have been biochemically or genetically characterized, ,− e.g. , those from Escherichia coli (EcDHAD), Mycobacterium tuberculosis (MbDHAD), Sulfolobus solfataricus (SsDHAD), and Arabidopsis thaliana (AtDHAD).…”

Section: Introductionmentioning

confidence: 99%

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Cyanobacterial Dihydroxyacid Dehydratases Are a Promising Growth Inhibition Target

et al. 2020

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Microbes are essential to the global ecosystem, but undesirable microbial growth causes issues ranging from food spoilage and infectious diseases to harmful cyanobacterial blooms. The use of chemicals to control microbial growth has achieved significant success, while specific roles for a majority of essential genes in growth control remain unexplored. Here, we show the growth inhibition of cyanobacterial species by targeting an essential enzyme for the biosynthesis of branched-chain amino acids. Specifically, we report the biochemical, genetic, and structural characterization of dihydroxyacid dehydratase from the model cyanobacterium Synechocystis sp. PCC 6803 (SnDHAD). Our studies suggest that SnDHAD is an oxygen-stable enzyme containing a [2Fe-2S] cluster. Furthermore, we demonstrate that SnDHAD is selectively inhibited in vitro and in vivo by the natural product aspterric acid, which also inhibits the growth of representative bloom-forming Microcystis and Anabaena strains but has minimal effects on microbial pathogens with [4Fe-4S] containing DHADs. This study suggests DHADs as a promising target for the precise growth control of microbes and highlights the exploration of other untargeted essential genes for microbial management.

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The inactivation of dihydroxy-acid dehydratase in Escherichia coli treated with hyperbaric oxygen occurs because of the destruction of its Fe-S cluster, but the enzyme remains in the cell in a form that can be reactivated.

Cited by 103 publications

References 25 publications

Tellurite-mediated disabling of [4Fe–4S] clusters of Escherichia coli dehydratases

Tellurite-mediated disabling of [4Fe–4S] clusters of Escherichia coli dehydratases

How Microbes Defend Themselves From Incoming Hydrogen Peroxide

Cyanobacterial Dihydroxyacid Dehydratases Are a Promising Growth Inhibition Target

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