Dataset Information

Nitrate reduction to ammonia by Acididesulfobacillus acetoxydans, an acidophilic sulfate reducing bacterium

ABSTRACT: Acididesulfobacillus acetoxydans is an acidophilic sulfate reducer that can dissimilatory reduce nitrate to ammonia (DNRA). However, no known nitrite reductase is encoded. This study was performed to investigate how A. acetoxydans reduces nitrate to nitrite and elucidated a novel DNRA mechanism and potential nitrosative stress resistance mechanisms in acidophiles.

INSTRUMENT(S): Orbitrap Exploris 480

ORGANISM(S): Acididesulfobacillus Acetoxydans

SUBMITTER: Sjef Boeren

LAB HEAD: Sjef Boeren

PROVIDER: PXD045135 | Pride | 2024-01-26

REPOSITORIES: Pride

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A novel mechanism for dissimilatory nitrate reduction to ammonium in <i>Acididesulfobacillus acetoxydans</i>.

Egas Reinier A RA Kurth Julia M JM Boeren Sjef S Sousa Diana Z DZ Welte Cornelia U CU Sánchez-Andrea Irene I

mSystems 20240207 3

The biological route of nitrate reduction has important implications for the bioavailability of nitrogen within ecosystems. Nitrate reduction via nitrite, either to ammonium (ammonification) or to nitrous oxide or dinitrogen (denitrification), determines whether nitrogen is retained within the system or lost as a gas. The acidophilic sulfate-reducing bacterium (aSRB) <i>Acididesulfobacillus acetoxydans</i> can perform dissimilatory nitrate reduction to ammonium (DNRA). While encoding a Nar-type ...[more]

PMID: 38323850

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Project description:Cellular respiration is a fundamental process undergone within energy-transducing membranes through the redox activity of multimeric protein assemblies, so-called respiratory complexes. In most cases, electron transport is ensured by lipophilic molecules, quinones, serving as electron shuttles. This redox activity is coupled to the net translocation of protons across the membrane thereby establishing an electrochemical gradient, the protonmotive force (pmf). Such a gradient powers the transport of molecules (such as proteins, ions or antibiotics) and ATP synthesis but was also shown to participate in protein localization in prokaryotes. Importantly, energy-transducing membranes show a high level of organization with heterogeneous distribution of respiratory complexes as observed across several bacterial lineages. Although electron transport in energy-transducing membranes is considered to be a kinetic process coupled to the diffusion of all reactants and in particular quinones, it is not clear to which extent subcellular distribution of respiratory complexes can have an influence on the overall kinetics. We previously evidenced polar clustering of nitrate reductase, NarGHI, an anaerobic respiratory complex in the gut bacterium Escherichia coli. Such spatial organization was shown to directly impact the electron flux of the associated respiratory chain. While dynamic localization of such complex plays an important role in controlling respiration, the mechanism by which it impacts the electron flux is not understood. Yet, under such conditions where nitrate is the sole terminal electron acceptor, functioning of the electron transport chain in enteric bacteria such as E. coli and Salmonella typhimurium is associated with the production of nitric oxide (NO) mainly resulting from the reduction of nitrite by nitrate reductase. As a consequence, both E. coli and S. typhimurium produce a multitude of enzymes controlling NO homeostasis, the primary source of nitrosative stress. Protein S-nitrosylation is a ubiquitous NO-dependent post-translational modification of cysteine that regulates protein structure and function. Recently, Seth et al demonstrated that, in absence of oxygen, NO oxidation is mainly catalyzed by the hybrid cluster protein Hcp allowing its further reaction with thiols of a broad spectrum of proteins. Among Hcp-dependent S-nitrosylated targets are the nitrate reductase complex, multiple metabolic enzymes and the transcription factor OxyR whose S-nitrosylation entails a distinct nitrosative stress regulon. Optimizing electron transport through clustering of nitrate reductase will lead to nitrite accumulation which may in turn be responsible for NO production. Here, the electron-donating respiratory complex, the formate dehydrogenase, FdnGHI was shown to cluster at the poles under nitrate respiring conditions. Its proximity with the nitrate reductase complex was confirmed by evaluating the interactome of the later under distinct metabolic conditions reported to impact its subcellular organization. All the identified partners were exclusively found when cells were grown under nitrate respiration. The proximity of two respiratory complexes provides mechanistic explanation on the importance of subcellular organization onto quinone pool turnover. Noteworthy is the identification of several components playing key roles in the protection against endogenous nitrosative stress.

			Action	DRS
	DMS217_Sulf_1.raw	Raw
	DMS218_Sulf_2.raw	Raw
	DMS219_Sulf_3.raw	Raw
	DMS220_Sulf_4.raw	Raw
	DMS221_Nitr_1.raw	Raw