Cloning and characterization of nnrR, whose product is required for the expression of proteins involved in nitric oxide metabolism in Rhodobacter sphaeroides 2.4.3

Tosques, I E; Shi, Jiarong; Shapleigh, James P.

doi:10.1128/jb.178.16.4958-4964.1996

Cited by 94 publications

(136 citation statements)

References 39 publications

(56 reference statements)

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“…The strategy used to generate strains 29.10 and 15.12, which contain Tn5 (Tp r ) insertions, was described by Tosques et al (35). To generate the transposon (Tn) insertion used to construct R. sphaeroides strains containing Tn-lacZ (23), either the 5.9-kb PstI fragment or the 3.7-kb PstI fragment was mutagenized by being placed in trans in E. coli CC170, which contains a single chromosomal copy of Tn-lacZ (24).…”

Section: Methodsmentioning

confidence: 99%

“…A 3.4-kb XhoI-PstI fragment from the 5.9-kb PstI fragment was used to generate pTB246. The construction of the norB-lacZ transcriptional fusion plasmid pIT9 has been previously described (35).…”

Section: Methodsmentioning

confidence: 99%

“…Rhodobacter strains were grown in Sistrom's medium at 30°C. Procedures for growing wild-type and mutant R. sphaeroides strains anaerobically and microaerobically are described elsewhere (35).…”

Section: Methodsmentioning

confidence: 99%

“…DNA sequencing was done with single-stranded DNA by the chain termination method with materials and protocols from the Sequenase version 2.0 kit (U.S. Biochemicals) and 35 S-dATP (Amersham). Both strands of the region encoding nor were sequenced by using several different strategies, including making subclones for sequencing with the M13 reverse-sequencing primer, using custom primers to sequence gaps, and sequencing clones derived from partial Sau3AI digests with the M13 reverse-sequencing primer.…”

Section: Methodsmentioning

confidence: 99%

“…In Paracoccus denitrificans, the nor operon apparently consists of six genes, which include homologs of the three genes in the P. aeruginosa operon (8). Regulation of nor expression appears to be under the control of the nnrR product in P. denitrificans and Rhodobacter sphaeroides 2.4.3 and an apparent functional homolog of NnrR in P. aeruginosa (2,35,37). NnrR, which is a member of the Fnr/Crp family of transcriptional regulators, regulates both Nor and NO 2 Ϫ reductase (Nir) expression but does not appear to be involved in regulation of other aspects of denitrification.…”

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confidence: 99%

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Characterization of the nitric oxide reductase-encoding region in Rhodobacter sphaeroides 2.4.3

et al. 1997

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A gene cluster which includes genes required for the expression of nitric oxide reductase in Rhodobacter sphaeroides 2.4.3 has been isolated and characterized. Sequence analysis indicates that the two proximal genes in the cluster are the Nor structural genes. These two genes and four distal genes apparently constitute an operon. Mutational analysis indicates that the two structural genes, norC and norB, and the genes immediately downstream, norQ and norD, are required for expression of an active Nor complex. The remaining two genes, nnrT and nnrU, are required for expression of both Nir and Nor. The products of norCBQD have significant identity with products from other denitrifiers, whereas the predicted nnrT and nnrU gene products have no similarity with products corresponding to other sequences in the database. Mutational analysis and functional complementation studies indicate that the nnrT and nnrU genes can be expressed from an internal promoter. Deletion analysis of the regulatory region upstream of norC indicated that a sequence motif which has identity to a motif in the gene encoding nitrite reductase in strain 2.4.3 is critical for nor operon expression. Regulatory studies demonstrated that the first four genes, norCBQD, are expressed only when the oxygen concentration is low and nitrate is present but that the two distal genes, nnrTU, are expressed constitutively.Denitrification is the reduction of nitrate (NO 3 Ϫ ) to gaseous intermediates, principally nitrogen gas. Nitric oxide (NO), an obligatory intermediate during denitrification, is generated from the one-electron reduction of nitrite (NO 2 Ϫ ) (41). NO reduction is coupled to energy generation (18,29). NO is also a well-known cytotoxic compound, so its production during denitrification has the potential of causing significant cell damage. To mitigate the toxicity of NO, its steady-state concentration during denitrification is maintained at low-nanomolar levels (11). The protein responsible for NO reduction, NO reductase (Nor), catalyzes the reaction 2NO ϩ 2H ϩ 3N 2 O ϩ H 2 O. Nitrous oxide (N 2 O) is an inert, nontoxic intermediate that is frequently the terminal product of denitrification (42). Nor has been purified and shown to be a heterodimeric membrane protein (9,14,16). Metal analysis has shown that it contains only iron in stoichiometric amounts. Recently, the Nor structural genes have been characterized, and sequence analysis revealed that Nor was related to the cytochrome c oxidase superfamily (36). In particular, Nor is most closely related to the heme b-containing oxidases, which are expressed under conditions of low oxygen concentration. It has been suggested that Nor was the original member of this family and that the other members arose by modifying the Nor structure (26).The genetic organization of the region of the chromosome encoding the nor structural genes varies among denitrifiers. In Pseudomonas stutzeri, the two structural genes form a distinct transcriptional unit (43). In Pseudomonas aeruginosa, the two structural genes ...

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Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

Section: Methodsmentioning

confidence: 99%

mentioning

confidence: 99%

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Characterization of the nitric oxide reductase-encoding region in Rhodobacter sphaeroides 2.4.3

et al. 1997

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Anaerobic Respiration

Oren¹

2009

Encyclopedia of Life Sciences

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Many prokaryotes, Bacteria as well as Archaea, can obtain energy for growth in the absence of oxygen by anaerobic respiration. In this process, electrons are transferred to electron acceptors such as nitrate, sulfate, elemental sulfur, carbon dioxide, oxidized metal ions such as Fe(III) and Mn(IV) and a range of other compounds including fumarate, dimethylsulfoxide, trimethylamine N ‐oxide, arsenate and selenate. In all these processes, respiratory electron transport is coupled to the generation of a transmembrane proton gradient and the formation of adenosine triphosphate (ATP). Anaerobic respiration processes are seldom encountered in eukaryotic organisms. Anaerobic respiration has an important impact on the cycle of matter in nature, including processes such as denitrification (dissimilatory reduction of nitrate and nitrite to gaseous nitrogen), dissimilatory sulfate reduction with the formation of sulfide, the formation of methane and acetate from carbon dioxide and different processes in the biogeochemical cycles of metals. Key concepts When oxygen is not available for respiration many prokaryotes can use alternative electron acceptors to obtain energy by respiration. Anaerobic respiration is widespread in the two domains of prokaryotes: the Bacteria and the Archaea. Some prokaryotes can perform both aerobic and anaerobic respiration; others are obligate anaerobes that cannot use oxygen as electron acceptor for respiration. Denitrification, or dissimilatory reduction of nitrate to gaseous nitrogen, is an important process in the global nitrogen cycle. In anaerobic environments sulfate serves as terminal electron acceptor and is reduced to sulfide, giving rise to both the formation of metal sulfides in sediments and the evolution of hydrogen sulfide gas. Carbon dioxide is used as terminal electron acceptor by methanogenic Archaea for energy generation, yielding methane as final product and by different groups of prokaryotes to produce acetate. Anaerobic respiration processes are involved in a wide range of reactions involving oxidized ions of metals (iron, manganese, chromium, uranium and others) and metalloids (arsenic, selenium). Anaerobic respiration has important economic implications, both favourable (e.g. conversion of bound nitrogen to nitrogen gas in water purification plants) and unfavourable (e.g. loss of available nitrogen in agricultural soils, corrosion of steel pipes mediated by sulfate‐reducing bacteria).

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FNR‐Like Proteins in Rhizobia: Past and Future

Zamorano‐Sánchez

Girard

2015

Biological Nitrogen Fixation

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Cloning and characterization of nnrR, whose product is required for the expression of proteins involved in nitric oxide metabolism in Rhodobacter sphaeroides 2.4.3

Cited by 94 publications

References 39 publications

Characterization of the nitric oxide reductase-encoding region in Rhodobacter sphaeroides 2.4.3

Characterization of the nitric oxide reductase-encoding region in Rhodobacter sphaeroides 2.4.3

Anaerobic Respiration

FNR‐Like Proteins in Rhizobia: Past and Future

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