scholarly journals Competition between Escherichia coli strains expressing either a periplasmic or a membrane-bound nitrate reductase: does Nap confer a selective advantage during nitrate-limited growth?

1999 ◽  
Vol 344 (1) ◽  
pp. 77-84 ◽  
Author(s):  
Laura C. POTTER ◽  
Paul MILLINGTON ◽  
Lesley GRIFFITHS ◽  
Gavin H. THOMAS ◽  
Jeffrey A. COLE
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Nitrate Reductase ◽  
Electron Acceptor ◽  
Physiological Role ◽  
Selective Advantage ◽  
Limited Growth ◽  
Terminal Electron Acceptor ◽  
Periplasmic Nitrate Reductase

The physiological role of the periplasmic nitrate reductase, Nap, one of the three nitrate reductases synthesized by Escherichia coli K-12, has been investigated. A series of double mutants that express only one nitrate reductase were grown anaerobically in batch cultures with glycerol as the non-fermentable carbon source and nitrate as the terminal electron acceptor. Only the strain expressing nitrate reductase A grew rapidly under these conditions. Introduction of a narL mutation severely decreased the growth rate of the nitrate reductase A strain, but enhanced the growth of the Nap+ strain. The ability to use nitrate as a terminal electron acceptor for anaerobic growth is therefore regulated primarily by the NarL protein at the level of transcription. Furthermore, the strain expressing nitrate reductase A had a substantial selective advantage in competition with the strain expressing only Nap during nitrate-sufficient continuous culture. However, the strain expressing Nap was preferentially selected during nitrate-limited continuous growth. The saturation constants for nitrate for the two strains (which numerically are equal to the nitrate concentrations at half of the maximum specific growth rate and therefore reflect the relative affinities for nitrate) were estimated using the integrated Monod equation to be 15 and 50 μM for Nap and nitrate reductase A respectively. This difference is sufficient to explain the selective advantage of the Nap+ strain during nitrate-limited growth. It is concluded that one physiological role of the periplasmic nitrate reductase of enteric bacteria is to enable bacteria to scavenge nitrate in nitrate-limited environments.

Oxygen control of nitrogen oxide respiration, focusing on α-proteobacteria

2011 ◽  
Vol 39 (1) ◽  
pp. 179-183 ◽  
Author(s):  
James P. Shapleigh
Keyword(s):  
Nitrate Reductase ◽  
Nitrogen Oxide ◽  
Physiological Function ◽  
Physiological Role ◽  
Present Review ◽  
Oxygen Control ◽  
Anoxic Conditions ◽  
Periplasmic Nitrate Reductase

Denitrification is generally considered to occur under micro-oxic or anoxic conditions. With this in mind, the physiological function and regulation of several steps in the denitrification of model α-proteobacteria are compared in the present review. Expression of the periplasmic nitrate reductase is quite variable, with this enzyme being maximally expressed under oxic conditions in some bacteria, but under micro-oxic conditions in others. Expression of nitrite and NO reductases in most denitrifiers is more tightly controlled, with expression only occurring under micro-oxic conditions. A possible exception to this may be Roseobacter denitrificans, but the physiological role of these enzymes under oxic conditions is uncertain.

Physiological role of GlpB of anaerobic glycerol-3-phosphate dehydrogenase ofEscherichia coli

1995 ◽  
Vol 73 (3-4) ◽  
pp. 147-153 ◽  
Author(s):  
Monica E. R. Varga ◽  
Joel H. Weiner
Keyword(s):  
Escherichia Coli ◽  
Physiological Role ◽  
Anaerobic Growth ◽  
Paramagnetic Resonance ◽  
Terminal Electron Acceptor ◽  
Iron Sulfur Center ◽  
Anaerobic Electron Transport ◽  
Membrane Bound ◽  
Glycerol 3 Phosphate Dehydrogenase

Anaerobic sn-glycerol-3-phosphate dehydrogenase of Escherichia coli is encoded by an operon of three genes, glpACB. The promoter distal gene, glpB, encodes a 44-kilodalton polypeptide that is not part of the purified soluble dehydrogenase. By recombinant plasmid complementation, in a strain harboring a chromosomal deletion of glpACB, we found that all three genes were essential for anaerobic growth on glycerol-3-phosphate (G3P). By isolation of inner membrane preparations we confirmed the cytoplasmic membrane localization of GlpB. GlpB displayed an electron paramagnetic resonance spectrum that suggested the presence of iron–sulfur center(s) within GlpB. We used this spectrum to show that the center(s) were reduced by the artificial reductant dithionite and by the physiological substrate G3P but not by lactate or formate. The center(s) were oxidized by fumarate. These data indicated that GlpB mediates electron transfer from the soluble GlpAC dimer to the terminal electron acceptor fumarate via the membrane-bound menaquinone pool.Key words: glycerol-3-phosphate dehydrogenase, anaerobic electron transport, membrane proteins, ferredoxin, Escherichia coli.

scholarly journals Role of growth rate on the orientational alignment of Escherichia coli in a slit

2017 ◽  
Vol 4 (6) ◽  
pp. 170463 ◽  
Author(s):  
Julian Sheats ◽  
Bianca Sclavi ◽  
Marco Cosentino Lagomarsino ◽  
Pietro Cicuta ◽  
Kevin D. Dorfman
Keyword(s):  
Escherichia Coli ◽  
Growth Rate ◽  
Aspect Ratio ◽  
Density Fluctuations ◽  
Global Alignment ◽  
Similar Amount ◽  
Cell Area ◽  
Nematic Ordering ◽  
Side Walls

We present experimental data on the nematic alignment of Escherichia coli bacteria confined in a slit, with an emphasis on the effect of growth rate and corresponding changes in cell aspect ratio. Global alignment with the channel walls arises from the combination of local nematic ordering of nearby cells, induced by cell division and the elongated shape of the cells, and the preferential orientation of cells proximate to the side walls of the slit. Decreasing the growth rate leads to a decrease in alignment with the walls, which is attributed primarily to effects of changing cell aspect ratio rather than changes in the variance in cell area. Decreasing confinement also reduces the degree of alignment by a similar amount as a decrease in the growth rate, but the distribution of the degree of alignment differs. The onset of alignment with the channel walls is coincident with the slits reaching their steady-state occupancy and connected to the re-orientation of locally aligned regions with respect to the walls during density fluctuations.

Effect of ascorbate on oxygen uptake and growth of Escherichia coli B

1988 ◽  
Vol 34 (6) ◽  
pp. 822-824 ◽  
Author(s):  
Holly E. Richter ◽  
Jacek Switala ◽  
Peter C. Loewen
Keyword(s):  
Escherichia Coli ◽  
Oxygen Uptake ◽  
Electron Acceptor ◽  
Minimal Medium ◽  
Anaerobic Growth ◽  
Rich Medium ◽  
Terminal Electron Acceptor ◽  
Subsequent Change ◽  
Escherichia Coli B

The addition of ascorbate to aerobically growing cultures of Escherichia coli B caused only a short pause in growth and no subsequent change in the rate or extent of growth. The effect of ascorbate on oxygen uptake varied from inhibition in minimal medium to stimulation in rich medium. Cyanide-resistant growth and oxygen uptake were stimulated by ascorbate. Both the rate and extent of anaerobic growth were stimulated in proportion to the amount of ascorbate added when fumarate was the terminal electron acceptor. Ascorbate had no effect on any aspect of anaerobic growth in the absence of a terminal electron acceptor or in the presence of nitrate.

scholarly journals Compensatory periplasmic nitrate reductase activity supports anaerobic growth ofPseudomonas aeruginosaPAO1 in the absence of membrane nitrate reductase

2009 ◽  
Vol 55 (10) ◽  
pp. 1133-1144 ◽  
Author(s):  
Nadine E. Van Alst ◽  
Lani A. Sherrill ◽  
Barbara H. Iglewski ◽  
Constantine G. Haidaris
Keyword(s):  
Nitrate Reductase ◽  
Response Regulator ◽  
Reductase Activity ◽  
Transcriptional Start Site ◽  
Atp Synthesis ◽  
Anaerobic Growth ◽  
Start Site ◽  
Terminal Electron Acceptor ◽  
Periplasmic Nitrate Reductase ◽  
Growth Recovery

Nitrate serves as a terminal electron acceptor under anaerobic conditions in Pseudomonas aeruginosa . Reduction of nitrate to nitrite generates a transmembrane proton motive force allowing ATP synthesis and anaerobic growth. The inner membrane-bound nitrate reductase NarGHI is encoded within the narK1K2GHJI operon, and the periplasmic nitrate reductase NapAB is encoded within the napEFDABC operon. The roles of the 2 dissimilatory nitrate reductases in anaerobic growth, and the regulation of their expressions, were examined by use of a set of deletion mutants in P. aeruginosa PAO1. NarGHI mutants were unable to grow anaerobically, but plate cultures remained viable up to 120 h. In contrast, the nitrate sensor-response regulator mutant ΔnarXL displayed growth arrest initially, but resumed growth after 72 h and reached the early stationary phase in liquid culture after 120 h. Genetic, transcriptional, and biochemical studies demonstrated that anaerobic growth recovery by the NarXL mutant was the result of NapAB periplasmic nitrate reductase expression. A novel transcriptional start site for napEFDABC expression was identified in the NarXL mutant grown anaerobically. Furthermore, mutagenesis of a consensus NarL-binding site monomer upstream of the novel transcriptional start site restored anaerobic growth recovery in the NarXL mutant. The data suggest that during anaerobic growth of wild-type P. aeruginosa PAO1, the nitrate response regulator NarL directly represses expression of periplasmic nitrate reductase, while inducing maximal expression of membrane nitrate reductase.

scholarly journals Escherichia coli NsrR Regulates a Pathway for the Oxidation of 3-Nitrotyramine to 4-Hydroxy-3-Nitrophenylacetate

2008 ◽  
Vol 190 (18) ◽  
pp. 6170-6177 ◽  
Author(s):  
Linda D. Rankin ◽  
Diane M. Bodenmiller ◽  
Jonathan D. Partridge ◽  
Shirley F. Nishino ◽  
Jim C. Spain ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Physiological Role ◽  
Growth Conditions ◽  
Growth Defect ◽  
E Coli ◽  
Mutant Phenotypes ◽  
Culture Supernatants ◽  
Chip Chip

ABSTRACT Chromatin immunoprecipitation and microarray (ChIP-chip) analysis showed that the nitric oxide (NO)-sensitive repressor NsrR from Escherichia coli binds in vivo to the promoters of the tynA and feaB genes. These genes encode the first two enzymes of a pathway that is required for the catabolism of phenylethylamine (PEA) and its hydroxylated derivatives tyramine and dopamine. Deletion of nsrR caused small increases in the activities of the tynA and feaB promoters in cultures grown on PEA. Overexpression of nsrR severely retarded growth on PEA and caused a marked repression of the tynA and feaB promoters. Both the growth defect and the promoter repression were reversed in the presence of a source of NO. These results are consistent with NsrR mediating repression of the tynA and feaB genes by binding (in an NO-sensitive fashion) to the sites identified by ChIP-chip. E. coli was shown to use 3-nitrotyramine as a nitrogen source for growth, conditions which partially induce the tynA and feaB promoters. Mutation of tynA (but not feaB) prevented growth on 3-nitrotyramine. Growth yields, mutant phenotypes, and analyses of culture supernatants suggested that 3-nitrotyramine is oxidized to 4-hydroxy-3-nitrophenylacetate, with growth occurring at the expense of the amino group of 3-nitrotyramine. Accordingly, enzyme assays showed that 3-nitrotyramine and its oxidation product (4-hydroxy-3-nitrophenylacetaldehyde) could be oxidized by the enzymes encoded by tynA and feaB, respectively. The results suggest that an additional physiological role of the PEA catabolic pathway is to metabolize nitroaromatic compounds that may accumulate in cells exposed to NO.

Evidence against the physiological role of acetyl phosphate in the phosphorylation of the ArcA response regulator in Escherichia coli

2009 ◽  
Vol 47 (5) ◽  
pp. 657-662 ◽  
Author(s):  
Xueqiao Liu ◽  
Gabriela R. Peña Sandoval ◽  
Barry L. Wanner ◽  
Won Seok Jung ◽  
Dimitris Georgellis ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Response Regulator ◽  
Physiological Role ◽  
Acetyl Phosphate

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.

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