NifA- and CooA-Coordinated
            <i>cowN</i>
            Expression Sustains Nitrogen Fixation by Rhodobacter capsulatus in the Presence of Carbon Monoxide

Hoffmann, Marie-Christine; Pfänder, Yvonne; Fehringer, Maria; Narberhaus, Franz; Masepohl, Bernd

doi:10.1128/jb.01754-14

Cited by 14 publications

(19 citation statements)

References 51 publications

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“…Interestingly, the characterization of these genes in R. rubrum using PSI‐Blast searches revealed that they are widespread and generally presents similar organization in nitrogen‐fixing bacteria. The importance of CooA and CowN for Mo‐nitrogenase‐dependent functioning in the presence of CO was shown to R. rubrum and R. capsulatus , but not to the Fe‐dependent nitrogenase of the latter . The authors suggested that CooA and CowN may act as a two component system that senses and modulates the Mo‐dependent nitrogenase activity by protecting it in the presence of CO in R. capsulatus and also in many others nitrogen fixing organisms.…”

Section: The Gluconacetobacter Genusmentioning

confidence: 99%

Nitrogen fixing bacteria in the family Acetobacteraceae and their role in agriculture

Reis

Teixeira

2015

J. Basic Microbiol.

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For centuries, the Acetobacteraceae is known as a family that harbors many species of organisms of biotechnological importance for industry. Nonetheless, since 1988 representatives of this family have also been described as nitrogen fixing bacteria able to plant growth promotion by a variety of mechanisms. Nitrogen fixation is a biological process that guarantees that the atmospheric N2 is incorporated into organic matter by several bacterial groups. Most representatives of this group, also known as diazotrophic, are generally associated with soil rhizosphere of many plants and also establishing a more specific association living inside roots, leaves, and others plants tissues as endophyte. Their roles as plant growth-promoting microorganisms are generally related to increase in plant biomass, phosphate and other mineral solubilization, and plant pathogen control. Here, we report many of these plant growth-promoting processes related to nitrogen fixing species already described in Acetobacteraceae family, especially Gluconacetobacter diazotrophicus and their importance to agriculture. In addition, a brief review of the state of art of the phylogenetics, main physiological and biochemical characteristics, molecular and functional genomic data of this group of Acetobacteraceae is presented.

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Section: The Gluconacetobacter Genusmentioning

confidence: 99%

Nitrogen fixing bacteria in the family Acetobacteraceae and their role in agriculture

Reis

Teixeira

2015

J. Basic Microbiol.

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“…Unsurprisingly, diazotrophs have evolved defenses to prevent inhibition of nitrogen fixation by CO. Protection against CO is best described in Rhodospirillum rubrum ( 19 ) and Rhodobacter capsulatus ( 20 ). Both organisms are able to grow diazotrophically in the presence of CO.…”

mentioning

confidence: 99%

CowN sustains nitrogenase turnover in the presence of the inhibitor carbon monoxide

Medina

Bretzing

Aviles

et al. 2021

Journal of Biological Chemistry

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Nitrogenase is the only enzyme capable of catalyzing nitrogen fixation, the reduction of dinitrogen gas (N 2 ) to ammonia (NH 3 ). Nitrogenase is tightly inhibited by the environmental gas carbon monoxide (CO). Nitrogen-fixing bacteria rely on the protein CowN to grow in the presence of CO. However, the mechanism by which CowN operates is unknown. Here, we present the biochemical characterization of CowN and examine how CowN protects nitrogenase from CO. We determine that CowN interacts directly with nitrogenase and that CowN protection observes hyperbolic kinetics with respect to CowN concentration. At a CO concentration of 0.001 atm, CowN restores nearly full nitrogenase activity. Our results further indicate that CowN’s protection mechanism involves decreasing the binding affinity of CO to nitrogenase’s active site approximately tenfold without interrupting substrate turnover. Taken together, our work suggests CowN is an important auxiliary protein in nitrogen fixation that engenders CO tolerance to nitrogenase.

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“…To examine the role of IscN in nitrogen fixation, nonpolar iscN deletions were introduced into the R. capsulatus B10S wildtype strain and the BS85 ⌬nifDK strain (see Materials and Methods). B10S is capable of fixing N 2 using either Mo-or Fe-nitrogenase, while BS85 is no longer able to synthesize Mo-nitrogenase but can still grow diazotrophically using Fe-nitrogenase (15,29). Parental and ⌬iscN strains grew comparably well with a fixed nitrogen source, ammonium, indicating that deletion of iscN does not cause general growth defects (data not shown).…”

Section: Mo Induces Accumulation Of the Mo-binding Mop Proteinmentioning

confidence: 82%

Proteome Profiling of the Rhodobacter capsulatus Molybdenum Response Reveals a Role of IscN in Nitrogen Fixation by Fe-Nitrogenase

et al. 2016

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Rhodobacter capsulatus is capable of synthesizing two nitrogenases, a molybdenum-dependent nitrogenase and an alternative Mo-free iron-only nitrogenase, enabling this diazotroph to grow with molecular dinitrogen (N 2 ) as the sole nitrogen source. Here, the Mo responses of the wild type and of a mutant lacking ModABC, the high-affinity molybdate transporter, were examined by proteome profiling, Western analysis, epitope tagging, and lacZ reporter fusions. Biological nitrogen fixation (BNF) is a central process in the global nitrogen cycle, which converts chemically inert atmospheric dinitrogen to ammonia, a bioavailable form of nitrogen. BNF is catalyzed by complex metalloenzymes called nitrogenases, which are exclusively found in diazotrophic bacteria and archaea but not in eukaryotes (1). All diazotrophs synthesize a molybdenum-dependent nitrogenase containing an iron-molybdenum cofactor, FeMoco. In addition to Mo-nitrogenases, some bacteria synthesize alternative Mo-free nitrogenases, which contain either an iron-vanadium cofactor, FeVco, or an iron-only cofactor, FeFeco (2). Alternative nitrogenases are less efficient than Monitrogenases in terms of consumption of reducing power and ATP per molecule of N 2 fixed (3, 4). Consequently, diazotrophs preferentially utilize Mo-nitrogenase as long as sufficient molybdate, the only bioavailable form of molybdenum, is available. To support Mo-nitrogenase activity under Mo-limiting conditions, most diazotrophs synthesize a high-affinity molybdate transporter, ModABC (1).The purple nonsulfur alphaproteobacterium Rhodobacter capsulatus is known for its metabolic versatility, and it has been used for decades as a model organism to study photosynthesis, hydrogen production, and nitrogen fixation (5-9). In particular, it is capable of using light energy to generate the ATP required for the energetically demanding nitrogen fixation process. R. capsulatus synthesizes two nitrogenases, namely, a Mo-nitrogenase and a Fenitrogenase but no V-nitrogenase (10, 11). The synthesis and activity of the two nitrogenases are controlled at the transcriptional, translational, and posttranslational levels by a regulatory cascade responding to ammonium and Mo availability (8, 9). Upon ammonium limitation, the nitrogen regulatory protein NtrC becomes activated by phosphorylation. In turn, NtrC-P activates transcription of nifA and anfA, which encode the transcription activators of Mo-nitrogenase and Fe-nitrogenase genes, respectively. At high Mo concentrations, anfA transcription is repressed by two structurally and functionally related Mo-responsive regu-

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NifA- and CooA-Coordinated cowN Expression Sustains Nitrogen Fixation by Rhodobacter capsulatus in the Presence of Carbon Monoxide

Cited by 14 publications

References 51 publications

Nitrogen fixing bacteria in the family Acetobacteraceae and their role in agriculture

Nitrogen fixing bacteria in the family Acetobacteraceae and their role in agriculture

CowN sustains nitrogenase turnover in the presence of the inhibitor carbon monoxide

Proteome Profiling of the Rhodobacter capsulatus Molybdenum Response Reveals a Role of IscN in Nitrogen Fixation by Fe-Nitrogenase

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