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Article ; Online: How a natural antibiotic uses oxidative stress to kill oxidant-resistant bacteria.

Gupta, Anshika / Imlay, James A

Proceedings of the National Academy of Sciences of the United States of America

2023 Volume 120, Issue 52, Page(s) e2312110120

Abstract: Natural products that possess antibiotic and antitumor qualities are often suspected of working through oxidative mechanisms. In this study, two quinone-based small molecules were compared. Menadione, a classic redox-cycling compound, was confirmed to ... ...

Abstract	Natural products that possess antibiotic and antitumor qualities are often suspected of working through oxidative mechanisms. In this study, two quinone-based small molecules were compared. Menadione, a classic redox-cycling compound, was confirmed to generate high levels of reactive oxygen species inside
MeSH term(s)	Oxidants/pharmacology ; Oxidants/metabolism ; Hydrogen Peroxide/metabolism ; Anti-Bacterial Agents/pharmacology ; Anti-Bacterial Agents/metabolism ; Streptonigrin/metabolism ; Oxidative Stress ; Escherichia coli/genetics ; Oxygen/metabolism ; Iron/metabolism ; DNA/metabolism ; Quinones/metabolism
Chemical Substances	Oxidants ; Hydrogen Peroxide (BBX060AN9V) ; Anti-Bacterial Agents ; Streptonigrin (261Q3JB310) ; Oxygen (S88TT14065) ; Iron (E1UOL152H7) ; DNA (9007-49-2) ; Quinones
Language	English
Publishing date	2023-12-18
Publishing country	United States
Document type	Journal Article
ZDB-ID	209104-5
ISSN	1091-6490 ; 0027-8424
ISSN (online)	1091-6490
ISSN	0027-8424
DOI	10.1073/pnas.2312110120
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Article: Evidence that protein thiols are not primary targets of intracellular reactive oxygen species in growing

Eben, Stefanie S / Imlay, James A

Frontiers in microbiology

2023 Volume 14, Page(s) 1305973

Abstract: The oxidizability of cysteine residues is exploited in redox chemistry and as a source of stabilizing disulfide bonds, but it also raises the possibility that these side chains will be oxidized when they should not be. It has often been suggested that ... ...

Abstract	The oxidizability of cysteine residues is exploited in redox chemistry and as a source of stabilizing disulfide bonds, but it also raises the possibility that these side chains will be oxidized when they should not be. It has often been suggested that intracellular oxidative stress from hydrogen peroxide or superoxide may result in the oxidation of the cysteine residues of cytoplasmic proteins. That view seemed to be supported by the discovery that one cellular response to hydrogen peroxide is the induction of glutaredoxin 1 and thioredoxin 2. In this study we used model compounds as well as alkaline phosphatase to test this idea. Our results indicate that molecular oxygen, superoxide, and hydrogen peroxide are very poor oxidants of N-acetylcysteine and of the protein thiols of alkaline phosphatase
Language	English
Publishing date	2023-12-13
Publishing country	Switzerland
Document type	Journal Article
ZDB-ID	2587354-4
ISSN	1664-302X
ISSN	1664-302X
DOI	10.3389/fmicb.2023.1305973
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Article ; Online: Excess copper catalyzes protein disulfide bond formation in the bacterial periplasm but not in the cytoplasm.

Eben, Stefanie S / Imlay, James A

Molecular microbiology

2023 Volume 119, Issue 4, Page(s) 423–438

Abstract: Copper avidly binds thiols and is redox active, and it follows that one element of copper toxicity may be the generation of undesirable disulfide bonds in proteins. In the present study, copper oxidized the model thiol N-acetylcysteine in vitro. Alkaline ...

Abstract	Copper avidly binds thiols and is redox active, and it follows that one element of copper toxicity may be the generation of undesirable disulfide bonds in proteins. In the present study, copper oxidized the model thiol N-acetylcysteine in vitro. Alkaline phosphatase (AP) requires disulfide bonds for activity, and copper activated reduced AP both in vitro and when it was expressed in the periplasm of mutants lacking their native disulfide-generating system. However, AP was not activated when it was expressed in the cytoplasm of copper-overloaded cells. Similarly, this copper stress failed to activate OxyR, a transcription factor that responds to the creation of a disulfide bond. The elimination of cellular disulfide-reducing systems did not change these results. Nevertheless, in these cells, the cytoplasmic copper concentration was high enough to impair growth and completely inactivate enzymes with solvent-exposed [4Fe-4S] clusters. Experiments with N-acetylcysteine determined that the efficiency of thiol oxidation is limited by the sluggish pace at which oxygen regenerates copper(II) through oxidation of the thiyl radical-Cu(I) complex. We conclude that this slow step makes copper too inefficient a catalyst to create disulfide stress in the thiol-rich cytoplasm, but it can still impact the few thiol-containing proteins in the periplasm. It also ensures that copper accumulates intracellularly in the Cu(I) valence.
MeSH term(s)	Copper/metabolism ; Escherichia coli/metabolism ; Periplasm/metabolism ; Acetylcysteine/metabolism ; Cytoplasm/metabolism ; Bacteria/metabolism ; Oxidation-Reduction ; Transcription Factors/metabolism ; Sulfhydryl Compounds/metabolism ; Alkaline Phosphatase/genetics ; Alkaline Phosphatase/metabolism ; Disulfides/metabolism
Chemical Substances	Copper (789U1901C5) ; Acetylcysteine (WYQ7N0BPYC) ; Transcription Factors ; Sulfhydryl Compounds ; Alkaline Phosphatase (EC 3.1.3.1) ; Disulfides
Language	English
Publishing date	2023-02-22
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	619315-8
ISSN	1365-2958 ; 0950-382X
ISSN (online)	1365-2958
ISSN	0950-382X
DOI	10.1111/mmi.15032
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Article ; Online: Escherichia coli induces DNA repair enzymes to protect itself from low-grade hydrogen peroxide stress.

Gupta, Anshika / Imlay, James A

Molecular microbiology

2022 Volume 117, Issue 4, Page(s) 754–769

Abstract: Escherichia coli responds to hydrogen peroxide ( ... ...

Abstract	Escherichia coli responds to hydrogen peroxide (H
MeSH term(s)	DNA ; DNA Repair ; DNA Repair Enzymes ; Escherichia coli ; Hydrogen Peroxide/pharmacology ; Oxidative Stress
Chemical Substances	DNA (9007-49-2) ; Hydrogen Peroxide (BBX060AN9V) ; DNA Repair Enzymes (EC 6.5.1.-)
Language	English
Publishing date	2022-01-13
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	619315-8
ISSN	1365-2958 ; 0950-382X
ISSN (online)	1365-2958
ISSN	0950-382X
DOI	10.1111/mmi.14870
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Article ; Online: Escherichia coli Uses a Dedicated Importer and Desulfidase To Ferment Cysteine.

Zhou, Yidan / Imlay, James A

mBio

2022 Volume 13, Issue 2, Page(s) e0296521

Abstract: CyuA of Escherichia coli is an inducible desulfidase that degrades cysteine to pyruvate, ammonium, and hydrogen sulfide. Workers have conjectured that its role may be to defend bacteria against the toxic effects of cysteine. However, ...

Abstract	CyuA of Escherichia coli is an inducible desulfidase that degrades cysteine to pyruvate, ammonium, and hydrogen sulfide. Workers have conjectured that its role may be to defend bacteria against the toxic effects of cysteine. However,
MeSH term(s)	Amino Acids/metabolism ; Carbon/metabolism ; Cysteine/metabolism ; Escherichia coli/genetics ; Escherichia coli/metabolism ; Humans ; Oxygen/metabolism ; Pyruvic Acid/metabolism ; Serine ; Threonine
Chemical Substances	Amino Acids ; Threonine (2ZD004190S) ; Serine (452VLY9402) ; Carbon (7440-44-0) ; Pyruvic Acid (8558G7RUTR) ; Cysteine (K848JZ4886) ; Oxygen (S88TT14065)
Language	English
Publishing date	2022-04-04
Publishing country	United States
Document type	Journal Article ; Research Support, N.I.H., Extramural
ZDB-ID	2557172-2
ISSN	2150-7511 ; 2161-2129
ISSN (online)	2150-7511
ISSN	2161-2129
DOI	10.1128/mbio.02965-21
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Article ; Online: The vulnerability of radical SAM enzymes to oxidants and soft metals.

Rohaun, Sanjay Kumar / Imlay, James A

Redox biology

2022 Volume 57, Page(s) 102495

Abstract: Radical S-adenosylmethionine enzymes (RSEs) drive diverse biological processes by catalyzing chemically difficult reactions. Each of these enzymes uses a solvent-exposed [4Fe-4S] cluster to coordinate and cleave its SAM co-reactant. This cluster is ... ...

Abstract	Radical S-adenosylmethionine enzymes (RSEs) drive diverse biological processes by catalyzing chemically difficult reactions. Each of these enzymes uses a solvent-exposed [4Fe-4S] cluster to coordinate and cleave its SAM co-reactant. This cluster is destroyed during oxic handling, forcing investigators to work with these enzymes under anoxic conditions. Analogous substrate-binding [4Fe-4S] clusters in dehydratases are similarly sensitive to oxygen in vitro; they are also extremely vulnerable to reactive oxygen species (ROS) in vitro and in vivo. These observations suggested that ROS might similarly poison RSEs. This conjecture received apparent support by the observation that when E. coli experiences hydrogen peroxide stress, it induces a cluster-free isozyme of the RSE HemN. In the present study, surprisingly, the purified RSEs viperin and HemN proved quite resistant to peroxide and superoxide in vitro. Furthermore, pathways that require RSEs remained active inside E. coli cells that were acutely stressed by hydrogen peroxide and superoxide. Viperin, but not HemN, was gradually poisoned by molecular oxygen in vitro, forming an apparent [3Fe-4S]
MeSH term(s)	Oxidants/metabolism ; Reactive Oxygen Species/metabolism ; Superoxides/metabolism ; Hydrogen Peroxide/metabolism ; Escherichia coli/metabolism ; Copper/metabolism ; S-Adenosylmethionine/metabolism ; Iron-Sulfur Proteins ; Oxygen/metabolism
Chemical Substances	Oxidants ; Reactive Oxygen Species ; Superoxides (11062-77-4) ; Hydrogen Peroxide (BBX060AN9V) ; Copper (789U1901C5) ; S-Adenosylmethionine (7LP2MPO46S) ; Iron-Sulfur Proteins ; Oxygen (S88TT14065)
Language	English
Publishing date	2022-10-07
Publishing country	Netherlands
Document type	Journal Article
ZDB-ID	2701011-9
ISSN	2213-2317 ; 2213-2317
ISSN (online)	2213-2317
ISSN	2213-2317
DOI	10.1016/j.redox.2022.102495
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Article ; Online: How Microbes Defend Themselves From Incoming Hydrogen Peroxide.

Sen, Ananya / Imlay, James A

Frontiers in immunology

2021 Volume 12, Page(s) 667343

Abstract: 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 ... ...

Abstract	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
MeSH term(s)	Bacteria/classification ; Bacteria/metabolism ; Bacterial Proteins/metabolism ; Hydrogen Peroxide/metabolism ; Oxidation-Reduction ; Reactive Oxygen Species/metabolism ; Superoxides/metabolism ; Transcription Factors/metabolism
Chemical Substances	Bacterial Proteins ; Reactive Oxygen Species ; Transcription Factors ; Superoxides (11062-77-4) ; Hydrogen Peroxide (BBX060AN9V)
Language	English
Publishing date	2021-04-27
Publishing country	Switzerland
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Review
ZDB-ID	2606827-8
ISSN	1664-3224 ; 1664-3224
ISSN (online)	1664-3224
ISSN	1664-3224
DOI	10.3389/fimmu.2021.667343
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Article ; Online: Where in the world do bacteria experience oxidative stress?

Imlay, James A

Environmental microbiology

2018 Volume 21, Issue 2, Page(s) 521–530

Abstract: Reactive oxygen species - superoxide, hydrogen peroxide and hydroxyl radicals - have long been suspected of constraining bacterial growth in important microbial habitats and indeed of shaping microbial communities. Over recent decades, studies of ... ...

Abstract	Reactive oxygen species - superoxide, hydrogen peroxide and hydroxyl radicals - have long been suspected of constraining bacterial growth in important microbial habitats and indeed of shaping microbial communities. Over recent decades, studies of paradigmatic organisms such as Escherichia coli, Salmonella typhimurium, Bacillus subtilis and Saccharomyces cerevisiae have pinpointed the biomolecules that oxidants can damage and the strategies by which microbes minimize their injuries. What is lacking is a good sense of the circumstances under which oxidative stress actually occurs. In this MiniReview several potential natural sources of oxidative stress are considered: endogenous ROS formation, chemical oxidation of reduced species at oxic-anoxic interfaces, H
MeSH term(s)	Bacteria/metabolism ; Hydrogen Peroxide/metabolism ; Oxidants ; Oxidation-Reduction ; Oxidative Stress/physiology ; Superoxides/metabolism
Chemical Substances	Oxidants ; Superoxides (11062-77-4) ; Hydrogen Peroxide (BBX060AN9V)
Language	English
Publishing date	2018-11-19
Publishing country	England
Document type	Journal Article ; Review
ZDB-ID	2020213-1
ISSN	1462-2920 ; 1462-2912
ISSN (online)	1462-2920
ISSN	1462-2912
DOI	10.1111/1462-2920.14445
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Article ; Online: When anaerobes encounter oxygen: mechanisms of oxygen toxicity, tolerance and defence.

Lu, Zheng / Imlay, James A

Nature reviews. Microbiology

2021 Volume 19, Issue 12, Page(s) 774–785

Abstract: The defining trait of obligate anaerobes is that oxygen blocks their growth, yet the underlying mechanisms are unclear. A popular hypothesis was that these microorganisms failed to evolve defences to protect themselves from reactive oxygen species (ROS) ... ...

Abstract	The defining trait of obligate anaerobes is that oxygen blocks their growth, yet the underlying mechanisms are unclear. A popular hypothesis was that these microorganisms failed to evolve defences to protect themselves from reactive oxygen species (ROS) such as superoxide and hydrogen peroxide, and that this failure is what prevents their expansion to oxic habitats. However, studies reveal that anaerobes actually wield most of the same defences that aerobes possess, and many of them have the capacity to tolerate substantial levels of oxygen. Therefore, to understand the structures and real-world dynamics of microbial communities, investigators have examined how anaerobes such as Bacteroides, Desulfovibrio, Pyrococcus and Clostridium spp. struggle and cope with oxygen. The hypoxic environments in which these organisms dwell - including the mammalian gut, sulfur vents and deep sediments - experience episodic oxygenation. In this Review, we explore the molecular mechanisms by which oxygen impairs anaerobes and the degree to which bacteria protect their metabolic pathways from it. The emergent view of anaerobiosis is that optimal strategies of anaerobic metabolism depend upon radical chemistry and low-potential metal centres. Such catalytic sites are intrinsically vulnerable to direct poisoning by molecular oxygen and ROS. Observations suggest that anaerobes have evolved tactics that either minimize the extent to which oxygen disrupts their metabolism or restore function shortly after the stress has dissipated.
MeSH term(s)	Anaerobiosis ; Bacteria, Anaerobic/growth & development ; Bacteria, Anaerobic/metabolism ; Bacteroides/growth & development ; Bacteroides/metabolism ; Clostridium/growth & development ; Clostridium/metabolism ; Desulfovibrio/growth & development ; Desulfovibrio/metabolism ; Hydrogen Peroxide/metabolism ; Hydrogen Peroxide/toxicity ; Oxygen/metabolism ; Oxygen/toxicity ; Pyrococcus/growth & development ; Pyrococcus/metabolism ; Reactive Oxygen Species/metabolism ; Reactive Oxygen Species/toxicity ; Superoxides/metabolism ; Superoxides/toxicity
Chemical Substances	Reactive Oxygen Species ; Superoxides (11062-77-4) ; Hydrogen Peroxide (BBX060AN9V) ; Oxygen (S88TT14065)
Language	English
Publishing date	2021-06-28
Publishing country	England
Document type	Journal Article ; Research Support, N.I.H., Extramural ; Research Support, Non-U.S. Gov't ; Review
ZDB-ID	2139054-X
ISSN	1740-1534 ; 1740-1526
ISSN (online)	1740-1534
ISSN	1740-1526
DOI	10.1038/s41579-021-00583-y
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Zs.A 5865: Show issues			Location: Je nach Verfügbarkeit (siehe Angabe bei Bestand) bis Jg. 1994: Bestellungen von Artikeln über das Online-Bestellformular Jg. 1995 - 2021: Lesesall (2.OG) ab Jg. 2022: Lesesaal (EG)
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Article ; Online: Identifying the mediators of intracellular E. coli inactivation under UVA light: The (photo) Fenton process and singlet oxygen.

Giannakis, Stefanos / Gupta, Anshika / Pulgarin, Cesar / Imlay, James

Water research

2022 Volume 221, Page(s) 118740

Abstract: Solar disinfection (SODIS) was probed for its underlying mechanism. When Escherichia coli was exposed to UVA irradiation, the dominant solar fraction acting in SODIS process, cells exhibited a shoulder before death ensued. This profile resembles cell ... ...

Abstract	Solar disinfection (SODIS) was probed for its underlying mechanism. When Escherichia coli was exposed to UVA irradiation, the dominant solar fraction acting in SODIS process, cells exhibited a shoulder before death ensued. This profile resembles cell killing by hydrogen peroxide (H
MeSH term(s)	Catalase/genetics ; Escherichia coli/genetics ; Hydrogen Peroxide/metabolism ; Iron/metabolism ; Singlet Oxygen ; Ultraviolet Rays ; Water/metabolism
Chemical Substances	Water (059QF0KO0R) ; Singlet Oxygen (17778-80-2) ; Hydrogen Peroxide (BBX060AN9V) ; Iron (E1UOL152H7) ; Catalase (EC 1.11.1.6)
Language	English
Publishing date	2022-06-13
Publishing country	England
Document type	Journal Article
ZDB-ID	202613-2
ISSN	1879-2448 ; 0043-1354
ISSN (online)	1879-2448
ISSN	0043-1354
DOI	10.1016/j.watres.2022.118740
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