Regulation of Expression of Genes for Three Nitrogenases in Azotobacter Vinelandii

Kennedy, Christina; Bali, Anil; Blanco, Gonzalo; Contreras, Asunscion; Drummond, Martin; Merrick, Mike; Walmsley, Jean; Woodley, Paul

doi:10.1007/978-94-011-3486-6_2

Cited by 9 publications

(8 citation statements)

References 16 publications

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“…The in vivo production of CO under a CO2 atmosphere has been definitively attributed to NifH (or VnfH) by expression of the protein in a background containing deletions in the genes that encode for the catalytic component NifDK (or VnfDGK). In the presence of NH3, nitrogenase gene product expression is repressed [35], leading to no production of CO, whereas omission of NH3 from the media leads to expression of the Fe protein and reduction of CO2 [34]. Thus, this adventitious substrate reduction function may occur under nitrogen-fixing conditions in vivo, but the prevalence of the reaction and its physiological implications are not known at this time.…”

Section: Adventitious Reactivity Of Fe Proteinsmentioning

confidence: 99%

The Fe Protein: An Unsung Hero of Nitrogenase

Jasniewski

Sickerman

et al. 2018

Inorganics

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Although the nitrogen-fixing enzyme nitrogenase critically requires both a reductase component (Fe protein) and a catalytic component, considerably more work has focused on the latter species. Properties of the catalytic component, which contains two highly complex metallocofactors and catalyzes the reduction of N 2 into ammonia, understandably making it the "star" of nitrogenase. However, as its obligate redox partner, the Fe protein is a workhorse with multiple supporting roles in both cofactor maturation and catalysis. In particular, the nitrogenase Fe protein utilizes nucleotide binding and hydrolysis in concert with electron transfer to accomplish several tasks of critical importance. Aside from the ATP-coupled transfer of electrons to the catalytic component during substrate reduction, the Fe protein also functions in a maturase and insertase capacity to facilitate the biosynthesis of the two-catalytic component metallocofactors: fusion of the [Fe 8 S 7 ] P-cluster and insertion of Mo and homocitrate to form the matured [(homocitrate)MoFe 7 S 9 C] M-cluster. These and key structural-functional relationships of the indispensable Fe protein and its complex with the catalytic component will be covered in this review.

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Section: Adventitious Reactivity Of Fe Proteinsmentioning

confidence: 99%

The Fe Protein: An Unsung Hero of Nitrogenase

Jasniewski

Sickerman

et al. 2018

Inorganics

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“…Subsequently, it was used as a probe and prompted the identification of nifA-like genes in a large number of other diazotrophs. NifA-homologous proteins (VnfA, AnfA) are required for the regulation of alternative nitrogen fixation systems in Azotobacter vinelandii and Rhodobacter capsulatus (191,201,344 (278,304), B. japonicum (377), and Rhodobacter capsulatus (248).…”

Section: Nifamentioning

confidence: 99%

“…Nitrogen fixation has also been studied extensively in various other diazotrophs such as Azotobacter spp. (40,201), photosynthetic bacteria (213,314), cyanobacteria (56,157,158), Azospirillum spp. (120), rhizobia (27,87,96,102,163), and methanogenic bacteria (235).…”

Section: Introductionmentioning

confidence: 99%

Genetic regulation of nitrogen fixation in rhizobia.

Fischer¹

1994

Microbiological Reviews

456

274

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“…An additional problem regarding the molecular screening for nitrogenases is that the common Nifnitrogenase is only one out of three nitrogenases (Bishop, Jarlenski, and Hetherington 1980;Joerger and Bishop 1988;Kennedy et al 1991). Two alternative nitrogenases were described, one of which is the Anf nitrogenase, which is characterized by an iron-iron (Fe) co-enzyme, the other nitrogenase, Vnf, is a vanadium (V)-Fe nitrogenase, while, Nif has an Fe-Molybdenum (Mo) cofactor.…”

Section: Introductionmentioning

confidence: 99%

Facets of diazotrophy in the OMZ off Peru revisited- what we couldn’t see from a single marker gene approach

Christiansen

Löscher

2019

Preprint

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Correspondence to cloescher@biology.sdu.dk Significance statementThis study addresses the important process of N 2 fixation, based on a whole-metagenome and -transcriptome screening, reports an increased diversity of N 2 fixing microbes in the sulfidic shelf water off Peru, as compared to previous target-gene based studies from the same waters. In addition to a generally higher diversity, genes encoding for alternative nitrogenases, which were previously not subject of any study on N 2 fixation in oxygen minimum zones, were detected. The ecological meaning and evolutionary history of those alternative nitrogenases is subject of ongoing debates, however, their presence in OMZ waters would allow for N 2 fixation at extreme anoxia, which may become important in a future ocean challenged by progressive deoxygenation. AbstractBiological dinitrogen (N 2 ) fixation is the pathway making the large pool of atmospheric N 2 available to marine life. Besides direct rate measurements, a common approach to explore the potential for N 2 fixation in the ocean is a mining based on molecular genetic methods targeting the key functional gene nifH, coding for a subunit of the nitrogenase reductase. As novel sequencing and single cell techniques improved, our knowledge on the diversity of marine N 2 fixers grew exponentially. However, to date one aspect of N 2 fixation in the ocean is commonly left aside. This is the existence of two alternative types of nitrogenases, which are besides the Mo-Fe nitrogenase Nif, the Fe-Fe nitrogenase Anf, and the V-Fe nitrogenase Vnf, which differ with regard to their metal co-enzymes, as well as regarding their operon structure and composition. nifH-based studies may thus be biased, and alternative nitrogenases could not be recovered. Here, we screened a set of 6 metagenomes and -transcriptomes from a sulfidic water patch from the oxygen minimum zone off Peru for genes involved in N 2 fixation. We identified genes related to all three nitrogenases, and generally increased diversity as compared to our previous nifH-based study from the same waters. While we could not confirm gene expression of the alternative nitrogenases from our transcriptomes, we detected additional diazotrophs involved in N 2 fixation. We suggest that alternative nitrogenases may not be used under conditions present in those waters, however, depending on trace metal limitation in the future they may become active.

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Regulation of Expression of Genes for Three Nitrogenases in Azotobacter Vinelandii

Cited by 9 publications

References 16 publications

The Fe Protein: An Unsung Hero of Nitrogenase

The Fe Protein: An Unsung Hero of Nitrogenase

Genetic regulation of nitrogen fixation in rhizobia.

Facets of diazotrophy in the OMZ off Peru revisited- what we couldn’t see from a single marker gene approach

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