Function of the Rhizobium etli CFN42 nirK gene in nitrite metabolism

2005 ◽  
Vol 33 (1) ◽  
pp. 162-163 ◽  
Author(s):  
E. Bueno ◽  
N. Gómez-Hernández ◽  
L. Girard ◽  
E.J. Bedmar ◽  
M.J. Delgado
Keyword(s):  
Electron Acceptor ◽  
Mutational Analysis ◽  
Deficient Mutant ◽  
Rhizobium Etli ◽  
Wild Type ◽  
Anaerobic Conditions ◽  
Gene Encoding ◽  
Terminal Electron Acceptor ◽  
Nirk Gene ◽  
Nitrite Uptake

Rhizobium etli CFN42 is not capable of growing anaerobically with nitrate but it grows with nitrite as a terminal electron acceptor. This bacterium contains the nirK gene encoding the copper-containing Nir (nitrite reductase), which is located on the cryptic plasmid pCFN42f. Mutational analysis has demonstrated that a nirK deficient mutant was not capable of growing under nitrite-respiring conditions. Moreover, microaerobic growth of this mutant was inhibited by the presence of nitrite. Nir activity and nitrite uptake were highly diminished in a nirK mutant, compared with the wild-type levels after incubation under anaerobic conditions. Our results suggest that the copper-containing Nir may have both a respiratory and a nitrite-detoxifying role in R. etli.

scholarly journals The fixA and fixB Genes Are Necessary for Anaerobic Carnitine Reduction in Escherichia coli

2002 ◽  
Vol 184 (14) ◽  
pp. 4044-4047 ◽  
Author(s):  
Angelique Walt ◽  
Michael L. Kahn
Keyword(s):  
Escherichia Coli ◽  
Electron Acceptor ◽  
Anaerobic Conditions ◽  
Terminal Electron Acceptor ◽  
E Coli ◽  
Carnitine Metabolism

ABSTRACT In Escherichia coli, the use of carnitine as a terminal electron acceptor depends on a functional caiTABCDE operon. It had been suggested that the adjacent but divergent fixABCX operon is also required for carnitine metabolism, perhaps to provide electrons for carnitine reduction. We have constructed E. coli fixA and fixB mutants and find that they are unable to reduce carnitine to γ-butyrobetaine under anaerobic conditions.

scholarly journals Effect of the Deletion of qmoABC and the Promoter-Distal Gene Encoding a Hypothetical Protein on Sulfate Reduction in Desulfovibrio vulgaris Hildenborough

2010 ◽  
Vol 76 (16) ◽  
pp. 5500-5509 ◽  
Author(s):  
Grant M. Zane ◽  
Huei-che Bill Yen ◽  
Judy D. Wall
Keyword(s):  
Sulfate Reduction ◽  
Electron Acceptor ◽  
Transmembrane Protein ◽  
Hypothetical Protein ◽  
Desulfovibrio Vulgaris ◽  
Gene Encoding ◽  
Terminal Electron Acceptor ◽  
Sulfate Reducing ◽  
Reducing Bacteria

ABSTRACTThe pathway of electrons required for the reduction of sulfate in sulfate-reducing bacteria (SRB) is not yet fully characterized. In order to determine the role of a transmembrane protein complex suggested to be involved in this process, a deletion inDesulfovibrio vulgarisHildenborough was created by marker exchange mutagenesis that eliminated four genes putatively encoding the QmoABC complex and a hypothetical protein (DVU0851). The Qmo (quinone-interactingmembrane-boundoxidoreductase) complex is proposed to be responsible for transporting electrons to the dissimilatory adenosine-5′-phosphosulfate reductase in SRB. In support of the predicted role of this complex, the deletion mutant was unable to grow using sulfate as its sole electron acceptor with a range of electron donors. To explore a possible role for the hypothetical protein in sulfate reduction, a second mutant was constructed that had lost only the gene that codes for the DVU0851 protein. The second constructed mutant grew with sulfate as the sole electron acceptor; however, there was a lag that was not present with the wild-type or complemented strain. Neither deletion strain was significantly impaired for growth with sulfite or thiosulfate as the terminal electron acceptor. Complementation of the Δ(qmoABC-DVU0851) mutant with all four genes or only theqmoABCgenes restored its ability to grow by sulfate respiration. These results confirmed the prediction that the Qmo complex is in the electron pathway for sulfate reduction and revealed that no other transmembrane complex could compensate when Qmo was lacking.

scholarly journals Restoration of Cytoadherence to an Adherence-Deficient Mutant of Mycoplasma arthritidis by Genetic Complementation

2003 ◽  
Vol 71 (2) ◽  
pp. 671-675 ◽  
Author(s):  
Leigh R. Washburn ◽  
Daniel W. Bird ◽  
Kevin Dybvig
Keyword(s):  
Southern Hybridization ◽  
Single Copy ◽  
Lung Cells ◽  
Deficient Mutant ◽  
Wild Type ◽  
Western Immunoblotting ◽  
Gene Encoding ◽  
Experimental Conditions ◽  
Mycoplasma Arthritidis ◽  
Membrane Lipoprotein

ABSTRACT Mycoplasma arthritidis causes a severe septic arthritis in rats under natural and experimental conditions. An earlier study implicated a membrane lipoprotein designated MAA1 in cytadherence of M. arthritidis. In addition, a spontaneous adherence-deficient mutant was shown to contain a nonsense mutation in the gene encoding MAA1, resulting in production of a truncated product, MAA1Δ. In the present study, a wild-type maa1 gene carried on transposon Tn4001T was introduced into the low-adherence mutant by polyethylene glycol-mediated transformation. The presence of the tranposon and the wild-type maa1 gene in the chromosome of transformants was confirmed by PCR and Southern hybridization. The latter procedure also confirmed that each transformant contained a single copy of the transposon. Western immunoblotting showed that transformants produced both wild-type MAA1 and MAA1Δ, indicating that the introduced wild-type maa1 gene was functional. This phenotype was stably maintained after multiple subcultures even in the absence of antibiotic selection. Finally, transformants were shown to adhere to rat L-2 lung cells in culture at wild-type levels, providing confirmation for an important role for MAA1 in adherence.

Sulfate as a terminal electron acceptor in toluene oxidation in anaerobic conditions

2020 ◽  
Vol 22 (4) ◽  
pp. 157-167
Author(s):  
I. I. Ivanenkо ◽  
E. Y. Lapatina
Keyword(s):  
Electron Acceptor ◽  
Waste Water Treatment ◽  
Process Intensification ◽  
Petroleum Products ◽  
Electron Acceptors ◽  
Laboratory Research ◽  
Anaerobic Conditions ◽  
Active Sludge ◽  
Toluene Oxidation ◽  
Terminal Electron Acceptor

In aerobic conditions, many of microorganisms cause decomposition of saturated hydrocarbons. Little publications are available relative to anaerobic transformation of these compounds, which provides substantial сapiltal saving for waste water treatment. At the same time, cultures found among aerobic decomposers of petroleum products are characterized by the ability to use elements with variable valence as terminal electron acceptors in oxidation of organic substances. Their ability to decompose aliphatic hydrocarbons helps to identify some of them.Purpose: studying the ability of a selected association of immobilized bacteria on a fibrous carrier to utilize sulfate as a terminal electron acceptor for toluene oxidation.Methodology/approach: Analytical summarizing of results, literature review, laboratory research based on standard and modern up-to-date methodologies with the use of modern analytical equipment.Findings: The availability of using microorganism selection is shown for expanding the range of polluting strippants in biological purification; the main directions are determined for the process intensification by immobilization of active sludge on a fibrous carrier. The ability of microorganisms to oxidize toluene under oxygen-free (anaerobic) conditions is studied in the laboratory conditions.Research implications: monoaromatic hydrocarbons, toluene, in particular, can be changed by selected associations of decomposers using terminal electron acceptors in oxidation of nitrates and sulfates.

Detoxification of nitric oxide by the flavorubredoxin of Salmonella enterica serovar Typhimurium

2005 ◽  
Vol 33 (1) ◽  
pp. 198-199 ◽  
Author(s):  
P.C. Mills ◽  
D.J. Richardson ◽  
J.C.D. Hinton ◽  
S. Spiro
Keyword(s):  
Nitric Oxide ◽  
Nitrous Oxide ◽  
Salmonella Enterica ◽  
Salmonella Enterica Serovar Typhimurium ◽  
Mutant Phenotype ◽  
Wild Type ◽  
Anaerobic Conditions ◽  
Gene Encoding ◽  
Serovar Typhimurium ◽  
Oxygen Sensitive

Salmonella possesses multiple enzymes that utilize NO as a substrate, and could therefore contribute to the organism's ability to resist nitrosative killing by macrophages. Flavorubredoxin is an oxygen-sensitive enzyme that reduces NO to nitrous oxide. The Salmonella enterica serovar Typhimurium norV gene encoding flavorubredoxin was disrupted and the NO sensitivity of the mutant was determined. The norV mutant showed a greater sensitivity to NO than wild-type S. Typhimurium, but did recover growth after a transient inhibition. The mutant phenotype suggests that multiple enzymes are employed by S. Typhimurium to detoxify NO under anaerobic conditions, one of which is flavorubredoxin.

scholarly journals Mutational Analysis of the Rhizobium etli recA Operator

1998 ◽  
Vol 180 (23) ◽  
pp. 6325-6331 ◽  
Author(s):  
Angels Tapias ◽  
Jordi Barbé
Keyword(s):  
Complex Formation ◽  
Protein Complex ◽  
Mutational Analysis ◽  
Rhizobium Meliloti ◽  
Regulatory Sequence ◽  
Rhizobium Etli ◽  
Wild Type ◽  
Protein Complex Formation

ABSTRACT Based upon our earlier studies (A. Tapias, A. R. Fernández de Henestrosa, and J. Barbé, J. Bacteriol. 179:1573–1579, 1997) we hypothesized that the regulatory sequence of the Rhizobium etli recA gene was TTGN11CAA. However, further detailed analysis of the R. etli recAoperator described in the present work suggests that it may in fact be GAACN7GTAC. This new conclusion is based upon PCR mutagenesis analysis carried out in the R. etli recAoperator, which indicates that the GAAC and GTAC submotifs found in the sequence GAACN7GTAC are required for the maximal stimulation of in vivo transcription and in vitro DNA-protein complex formation. This DNA-protein complex is also detected when the GAACN7GTAC wild-type sequence is modified to obtain GAACN7GAAC, GTACN7GTAC, or GAACN7GTTC. The wild-type promoters of the Rhizobium meliloti and Agrobacterium tumefaciens recA genes, which also contain the GAACN7GTAC sequence, compete with the R. etli recA promoter for the DNA-protein complex formation but not with mutant derivatives in any of these motifs, indicating that the R. etli, R. meliloti, andA. tumefaciens recA genes present the same regulatory sequence.

Effects of an Autoregulatory Senescence-inhibitor Gene Construct on Nicotiana alata Link and Otto.

HortScience ◽  
1998 ◽  
Vol 33 (3) ◽  
pp. 519d-519 ◽  
Author(s):  
Kenneth R. Schroeder ◽  
Dennis P. Stimart
Keyword(s):  
Agrobacterium Tumefaciens ◽  
Plant Height ◽  
Dry Weight ◽  
Nicotiana Alata ◽  
Wild Type ◽  
Gene Encoding ◽  
Delayed Senescence ◽  
Gene Construct ◽  
Shoot Dry Weight ◽  
Inhibitor System

Nicotiana alata Link and Otto. was transformed via Agrobacterium tumefaciens encoding a senescence-specific promoter SAG12 cloned from Arabidopsis thaliana fused to a Agrobacterium tumefaciens gene encoding isopentenyl transferase (IPT) that catalyzes cytokinin synthesis. This was considered an autoregulatory senescence-inhibitor system. In 1996, we reported delayed senescence of intact flowers by 2 to 6 d and delayed leaf senescence of transgenic vs. wild-type N. alata. Further evaluations in 1997 revealed several other interesting effects of the SAG12-IPT gene construct. Measurement of chlorophyll content of mature leaves showed higher levels of both chlorophyll a and b in transgenic material under normal fertilization and truncated fertilization regimes. At 4 to 5 months of age transgenic plants expressed differences in plant height, branching, and dry weight. Plant height was reduced by 3 to 13 cm; branch counts increased 2 to 3 fold; and shoot dry weight increased up to 11 g over wild-type N. alata. These observations indicate the system is not tightly autoregulated and may prove useful to the floriculture industry for producing compact and more floriferous plants.

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