Anaerobic bacterial response to nitric oxide stress: Widespread misconceptions and physiologically relevant responses

Cole, Jeffrey A.

doi:10.1111/mmi.14713

Cited by 13 publications

(15 citation statements)

References 87 publications

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“…Rather than providing iron to repair metallo-proteins inactivated by NO, it was suggested that YtfE is an enzyme that releases NO, either directly or indirectly, into the cytoplasm. 27 , 28 We note that the R. eutropha YtfE orthologue NorA has been reported to reduce nitrite to NO in vitro. ( 38 ) Thus, YtfE may function as a NO-generating nitrite reductase.…”

Section: Resultsmentioning

confidence: 93%

The Di-Iron Protein YtfE Is a Nitric Oxide-Generating Nitrite Reductase Involved in the Management of Nitrosative Stress

et al. 2022

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Previously characterized nitrite reductases fall into three classes: siroheme-containing enzymes (NirBD), cytochrome c hemoproteins (NrfA and NirS), and copper-containing enzymes (NirK). We show here that the di-iron protein YtfE represents a physiologically relevant new class of nitrite reductases. Several functions have been previously proposed for YtfE, including donating iron for the repair of iron–sulfur clusters that have been damaged by nitrosative stress, releasing nitric oxide (NO) from nitrosylated iron, and reducing NO to nitrous oxide (N 2 O). Here, in vivo reporter assays confirmed that Escherichia coli YtfE increased cytoplasmic NO production from nitrite. Spectroscopic and mass spectrometric investigations revealed that the di-iron site of YtfE exists in a mixture of forms, including nitrosylated and nitrite-bound, when isolated from nitrite-supplemented, but not nitrate-supplemented, cultures. Addition of nitrite to di-ferrous YtfE resulted in nitrosylated YtfE and the release of NO. Kinetics of nitrite reduction were dependent on the nature of the reductant; the lowest K m , measured for the di-ferrous form, was ∼90 μM, well within the intracellular nitrite concentration range. The vicinal di-cysteine motif, located in the N-terminal domain of YtfE, was shown to function in the delivery of electrons to the di-iron center. Notably, YtfE exhibited very low NO reductase activity and was only able to act as an iron donor for reconstitution of apo-ferredoxin under conditions that damaged its di-iron center. Thus, YtfE is a high-affinity, low-capacity nitrite reductase that we propose functions to relieve nitrosative stress by acting in combination with the co-regulated NO-consuming enzymes Hmp and Hcp.

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Section: Resultsmentioning

confidence: 93%

The Di-Iron Protein YtfE Is a Nitric Oxide-Generating Nitrite Reductase Involved in the Management of Nitrosative Stress

et al. 2022

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“…Like CODHs, HCPs are widely distributed among (facultative) anaerobic microorganisms, including bacteria, archaea, and unicellular eukaryotes, of which several HCPs have been characterized [16–19] . Unlike CODHs, HCPs are unable to catalyze CO‐oxidation, [20] but support the reduction of hydroxylamine, peroxide and NO and the formation of S‐nitrosothiols [20–23] . The mechanistic basis for both reactivities, e.g.…”

Section: Introductionmentioning

confidence: 99%

A Morphing [4Fe‐3S‐nO]‐Cluster within a Carbon Monoxide Dehydrogenase Scaffold

et al. 2022

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Ni,Fe‐containing carbon monoxide dehydrogenases (CODHs) catalyze the reversible reduction of CO2 to CO. Several anaerobic microorganisms encode multiple CODHs in their genome, of which some, despite being annotated as CODHs, lack a cysteine of the canonical binding motif for the active site Ni,Fe‐cluster. Here, we report on the structure and reactivity of such a deviant enzyme, termed CooS‐VCh. Its structure reveals the typical CODH scaffold, but contains an iron‐sulfur‐oxo hybrid‐cluster. Although closely related to true CODHs, CooS‐VCh catalyzes neither CO oxidation, nor CO2 reduction. The active site of CooS‐VCh undergoes a redox‐dependent restructuring between a reduced [4Fe‐3S]‐cluster and an oxidized [4Fe‐2S‐S*‐2O‐2(H2O)]‐cluster. Hydroxylamine, a slow‐turnover substrate of CooS‐VCh, oxidizes the hybrid‐cluster in two structurally distinct steps. Overall, minor changes in CODHs are sufficient to accommodate a Fe/S/O‐cluster in place of the Ni,Fe‐heterocubane‐cluster of CODHs.

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“…It is most similar to NorA from C. necator (73% amino acid [AA] identity), and to YtfE from Salmonella enterica and DnrN from N. gonorrhoeae (∼50% AA identity). All three of these proteins have been implicated in nitrosative stress mitigation (Table S1A) ( 40 , 45 , 46 ). Rs NorA, NorB, and HmpX each contain the highly conserved heme- or globin metal cofactor-binding domains necessary to reduce NO toxicity (Fig.…”

Section: Resultsmentioning

confidence: 99%

NorA, HmpX, and NorB Cooperate to Reduce NO Toxicity during Denitrification and Plant Pathogenesis in Ralstonia solanacearum

et al. 2022

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The soilborne plant pathogen Ralstonia solanacearum ( Rs ) causes bacterial wilt, a serious and widespread threat to global food security. Rs is metabolically adapted to low-oxygen conditions, using denitrifying respiration to survive in the host and cause disease. However, bacterial denitrification and host defenses generate nitric oxide (NO), which is toxic and also alters signaling pathways in both the pathogen and its plant hosts. Rs mitigates NO with a trio of mechanistically distinct proteins: NO-reductase (NorB), predicted iron-binding (NorA), and oxidoreductase (HmpX).

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Anaerobic bacterial response to nitric oxide stress: Widespread misconceptions and physiologically relevant responses

Abstract: This is an open access article under the terms of the Creative Commons Attribution License, which permits use, distribution and reproduction in any medium, provided the original work is properly cited.

Cited by 13 publications

References 87 publications

The Di-Iron Protein YtfE Is a Nitric Oxide-Generating Nitrite Reductase Involved in the Management of Nitrosative Stress

The Di-Iron Protein YtfE Is a Nitric Oxide-Generating Nitrite Reductase Involved in the Management of Nitrosative Stress

A Morphing [4Fe‐3S‐nO]‐Cluster within a Carbon Monoxide Dehydrogenase Scaffold

NorA, HmpX, and NorB Cooperate to Reduce NO Toxicity during Denitrification and Plant Pathogenesis in Ralstonia solanacearum

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