scholarly journals Response of hya Expression to External pH in Escherichia coli

1999 ◽  
Vol 181 (17) ◽  
pp. 5250-5256 ◽  
Author(s):  
Paul W. King ◽  
Alan E. Przybyla
Keyword(s):  
Escherichia Coli ◽  
Alkaline Medium ◽  
Ph Value ◽  
Peak Level ◽  
Growth Conditions ◽  
Anaerobic Growth ◽  
Uptake Hydrogenase ◽  
Expression Levels ◽  
Alkaline Conditions ◽  
External Ph

ABSTRACT The hya operon of Escherichia coli is composed of the genes which synthesize uptake hydrogenase isoenzyme 1 (Hyd1). Although hya expression and Hyd1 synthesis occur only under anaerobic conditions, Hyd1 is not essential for growth. In this study we used a hya′-′lacZ fusion to characterize parameters of anaerobic growth that maximize hya expression in an attempt to further elucidate Hyd1 function. We found that the expression pattern of hya followed a decline of external pH. In buffered media where the pH value was set, the onset ofhya expression initiated earlier in growth and reached a greater peak level in acidic than in alkaline medium. When cultures expressing hya were shifted from acidic to alkaline conditions, hya expression was arrested; shifting from alkaline to acidic conditions stimulated hya expression. Maximal expression of hya under all growth conditions required the sigma factor RpoS and transcriptional regulators AppY and ArcA. In the absence of RpoS or AppY, the response of hyaexpression onset to external pH was evident and maximal hyalevels remained greater in acidic than in alkaline medium. However, the absence of ArcA led to a diminished response of expression onset to external pH and the loss of elevated expression at an acidic external pH. The fermentation end product formate slightly alteredhya expression levels but was not required forhya to respond to external pH. In contrast tohya expression, the onset of hyb operon expression, encoding uptake hydrogenase isoenzyme 2, was constitutive with respect to external pH. However, external pH did affecthyb expression levels, which, in contrast tohya, were maximal in alkaline rather than acidic medium.

scholarly journals Glutathionylspermidine metabolism in Escherichia coli

1995 ◽  
Vol 312 (2) ◽  
pp. 465-469 ◽  
Author(s):  
K Smith ◽  
A Borges ◽  
M R Ariyanayagam ◽  
A H Fairlamb
Keyword(s):  
Escherichia Coli ◽  
Glutathione Reductase ◽  
Growth Conditions ◽  
Anaerobic Growth ◽  
Growth Phases ◽  
Total Glutathione ◽  
Apparent Lack ◽  
E Coli ◽  
Catalytic Constant ◽  
Glutathione Disulphide

Intracellular levels of glutathione and glutathionylspermidine conjugates have been measured throughout the growth phases of Escherichia coli. Glutathionylspermidine was present in mid-log-phase cells, and under stationary and anaerobic growth conditions accounted for 80% of the total glutathione content. N1,N8-bis(glutathionyl)spermidine (trypanothione) was undetectable under all growth conditions. The catalytic constant kcat/Km of recombinant E. coli glutathione reductase for glutathionylspermidine disulphide was approx. 11,000-fold lower than that for glutathione disulphide. The much higher catalytic constant for the mixed disulphide of glutathione and glutathionylspermidine (11% that of GSSG), suggests a possible explanation for the low turnover of trypanothione disulphide by E. coli glutathione reductase, given the apparent lack of a specific glutathionylspermidine disulphide reductase in E. coli.

scholarly journals Lack of Protective Osmolytes Limits Final Cell Density and Volumetric Productivity of Ethanologenic Escherichia coli KO11 during Xylose Fermentation

2004 ◽  
Vol 70 (5) ◽  
pp. 2734-2740 ◽  
Author(s):  
S. A. Underwood ◽  
M. L. Buszko ◽  
K. T. Shanmugam ◽  
L. O. Ingram
Keyword(s):  
Escherichia Coli ◽  
Cell Growth ◽  
Citrate Synthase ◽  
Corn Steep Liquor ◽  
Cell Mass ◽  
Functional Expression ◽  
Growth Conditions ◽  
Volumetric Productivity ◽  
Anaerobic Growth ◽  
Mineral Salts

ABSTRACT Limited cell growth and the resulting low volumetric productivity of ethanologenic Escherichia coli KO11 in mineral salts medium containing xylose have been attributed to inadequate partitioning of carbon skeletons into the synthesis of glutamate and other products derived from the citrate arm of the anaerobic tricarboxylic acid pathway. The results of nuclear magnetic resonance investigations of intracellular osmolytes under different growth conditions coupled with those of studies using genetically modified strains have confirmed and extended this hypothesis. During anaerobic growth in mineral salts medium containing 9% xylose (600 mM) and 1% corn steep liquor, proline was the only abundant osmolyte (71.9 nmol ml−1 optical density at 550 nm [OD550] unit−1), and growth was limited. Under aerobic conditions in the same medium, twice the cell mass was produced, and cells contained a mixture of osmolytes: glutamate (17.0 nmol ml−1 OD550 unit−1), trehalose (9.9 nmol ml−1 OD550 unit−1), and betaine (19.8 nmol ml−1 OD550 unit−1). Two independent genetic modifications of E. coli KO11 (functional expression of Bacillus subtilis citZ encoding NADH-insensitive citrate synthase; deletion of ackA encoding acetate kinase) and the addition of a metabolite, such as glutamate (11 mM) or acetate (24 mM), as a supplement each increased the intracellular glutamate pool during fermentation, doubled cell growth, and increased volumetric productivity. This apparent requirement for a larger glutamate pool for increased growth and volumetric productivity was completely eliminated by the addition of a protective osmolyte (2 mM betaine or 0.25 mM dimethylsulfoniopropionate), consistent with adaptation to osmotic stress rather than relief of a specific biosynthetic requirement.

scholarly journals Anaerobic Expression of Escherichia coli Succinate Dehydrogenase: Functional Replacement of Fumarate Reductase in the Respiratory Chain during Anaerobic Growth

1998 ◽  
Vol 180 (22) ◽  
pp. 5989-5996 ◽  
Author(s):  
Elena Maklashina ◽  
Deborah A. Berthold ◽  
Gary Cecchini
Keyword(s):  
Escherichia Coli ◽  
Tricarboxylic Acid Cycle ◽  
Anaerobic Respiration ◽  
Growth Conditions ◽  
Fumarate Reductase ◽  
Anaerobic Growth ◽  
Enzyme Complex ◽  
Succinate Oxidation ◽  
Terminal Electron Acceptor ◽  
E Coli

ABSTRACT Succinate-ubiquinone oxidoreductase (SQR) from Escherichia coli is expressed maximally during aerobic growth, when it catalyzes the oxidation of succinate to fumarate in the tricarboxylic acid cycle and reduces ubiquinone in the membrane. The enzyme is similar in structure and function to fumarate reductase (menaquinol-fumarate oxidoreductase [QFR]), which participates in anaerobic respiration by E. coli. Fumarate reductase, which is proficient in succinate oxidation, is able to functionally replace SQR in aerobic respiration when conditions are used to allow the expression of the frdABCD operon aerobically. SQR has not previously been shown to be capable of supporting anaerobic growth ofE. coli because expression of the enzyme complex is largely repressed by anaerobic conditions. In order to obtain expression of SQR anaerobically, plasmids which utilize the PFRD promoter of the frdABCD operon fused to the sdhCDAB genes to drive expression were constructed. It was found that, under anaerobic growth conditions where fumarate is utilized as the terminal electron acceptor, SQR would function to support anaerobic growth ofE. coli. The levels of amplification of SQR and QFR were similar under anaerobic growth conditions. The catalytic properties of SQR isolated from anaerobically grown cells were measured and found to be identical to those of enzyme produced aerobically. The anaerobic expression of SQR gave a greater yield of enzyme complex than was found in the membrane from aerobically grown cells under the conditions tested. In addition, it was found that anaerobic expression of SQR could saturate the capacity of the membrane for incorporation of enzyme complex. As has been seen with the amplified QFR complex, E. coli accommodates the excess SQR produced by increasing the amount of membrane. The excess membrane was found in tubular structures that could be seen in thin-section electron micrographs.

Fumarate dependent protein composition under aerobic and anaerobic growth conditions in Escherichia coli

2020 ◽  
Vol 212 ◽  
pp. 103583 ◽  
Author(s):  
Kristin Surmann ◽  
Marius Stopp ◽  
Sebastian Wörner ◽  
Vishnu M. Dhople ◽  
Uwe Völker ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Protein Composition ◽  
Growth Conditions ◽  
Anaerobic Growth ◽  
Dependent Protein ◽  
Aerobic And Anaerobic Growth ◽  
Aerobic And Anaerobic

scholarly journals The NorR Protein of Escherichia coli Activates Expression of the Flavorubredoxin Gene norV in Response to Reactive Nitrogen Species

2002 ◽  
Vol 184 (16) ◽  
pp. 4640-4643 ◽  
Author(s):  
Matthew I. Hutchings ◽  
Neeraj Mandhana ◽  
Stephen Spiro
Keyword(s):  
Nitric Oxide ◽  
Escherichia Coli ◽  
Reactive Nitrogen Species ◽  
Regulatory Gene ◽  
Growth Conditions ◽  
Anaerobic Growth ◽  
Reactive Nitrogen ◽  
Nitrogen Species ◽  
Reactive Nitrogen Intermediates ◽  
Nitric Oxide Detoxification

ABSTRACT The Escherichia coli norVW genes encode a flavorubredoxin and NADH:(flavo)rubredoxin reductase, respectively, which are involved in nitric oxide detoxification under anaerobic growth conditions. Here it is shown that the norVW genes also have a role in protection against reactive nitrogen intermediates generated from nitroprusside. Transcription from the norV promoter is activated by the presence of nitroprusside in the growth medium; activation requires the product of a divergently transcribed regulatory gene, norR.

scholarly journals Genome-Wide Expression Analysis Indicates that FNR of Escherichia coli K-12 Regulates a Large Number of Genes of Unknown Function

2005 ◽  
Vol 187 (3) ◽  
pp. 1135-1160 ◽  
Author(s):  
Yisheng Kang ◽  
K. Derek Weber ◽  
Yu Qiu ◽  
Patricia J. Kiley ◽  
Frederick R. Blattner
Keyword(s):  
Gene Expression ◽  
Escherichia Coli ◽  
Dna Binding ◽  
Growth Conditions ◽  
Anaerobic Growth ◽  
Computer Search ◽  
Anaerobic Conditions ◽  
Metabolic Potential ◽  
Fermentation Products ◽  
K 12

ABSTRACT The major regulator controlling the physiological switch between aerobic and anaerobic growth conditions in Escherichia coli is the DNA binding protein FNR. To identify genes controlled by FNR, we used Affymetrix Antisense GeneChips to compare global gene expression profiles from isogenic MG1655 wild-type and Δfnr strains grown in glucose minimal media under aerobic or anaerobic conditions. We found that 297 genes contained within 184 operons were regulated by FNR and/or by O2 levels. The expression of many genes known to be involved in anaerobic respiration and fermentation was increased under anaerobic growth conditions, while that of genes involved in aerobic respiration and the tricarboxylic acid cycle were repressed as expected. The expression of nine operons associated with acid resistance was also increased under anaerobic growth conditions, which may reflect the production of acidic fermentation products. Ninety-one genes with no presently defined function were also altered in expression, including seven of the most highly anaerobically induced genes, six of which we found to be directly regulated by FNR. Classification of the 297 genes into eight groups by k-means clustering analysis indicated that genes with common gene expression patterns also had a strong functional relationship, providing clues for studying the function of unknown genes in each group. Six of the eight groups showed regulation by FNR; while some expression groups represent genes that are simply activated or repressed by FNR, others, such as those encoding functions for chemotaxis and motility, showed a more complex pattern of regulation. A computer search for FNR DNA binding sites within predicted promoter regions identified 63 new sites for 54 genes. We suggest that E. coli MG1655 has a larger metabolic potential under anaerobic conditions than has been previously recognized.

The sensor kinase DcuS of Escherichia coli: two stimulus input sites and a merged signal pathway in the DctA/DcuS sensor unit

2012 ◽  
Vol 393 (11) ◽  
pp. 1291-1297 ◽  
Author(s):  
Julian Witan ◽  
Christian Monzel ◽  
Patrick D. Scheu ◽  
Gottfried Unden
Keyword(s):  
Escherichia Coli ◽  
Target Genes ◽  
Response Regulator ◽  
Growth Conditions ◽  
Kinase Domain ◽  
Anaerobic Growth ◽  
Phosphoryl Transfer ◽  
Sensor Kinase ◽  
Signal Transfer ◽  
Sensor Unit

Abstract The membrane-integral sensor kinase DcuS of Escherichia coli consists of a periplasmically located sensory PASP domain, transmembrane helices TM1 and TM2, a cytoplasmic PASC domain and the kinase domain. Stimulus (C4-dicarboxylate) binding at PASP is required to stimulate phosphorylation of the kinase domain, resulting in phosphoryl transfer to the response regulator DcuR. PASC functions as a signaling device or a relay in signal transfer from TM2 to the kinase. Phosphorylated DcuR induces the expression of the target genes. Sensing by DcuS requires the presence of the C4-dicarboxylate transporter DctA during aerobic growth. DctA forms a sensor unit with DcuS, and a short C-terminal sequence of DctA forming the putative helix 8b is required for interaction with DcuS. Helix 8b contains a LDXXXLXXXL motif that is essential for function and interaction. DcuS requires the PASC domain for signal perception from DctA. Thus, DcuS and DctA form a DctA/DcuS sensory unit, and DcuS perceives stimuli from two different sites (PASP and DctA). The signal transfer pathways are supposed to merge at PASC. The fumarate/succinate antiporter DcuB takes over the role as a co-sensor of DcuS under anaerobic growth conditions.

scholarly journals Effect of Intracellular Expression of Antimicrobial Peptide LL-37 on Growth of Escherichia coli Strain TOP10 under Aerobic and Anaerobic Conditions

2013 ◽  
Vol 57 (10) ◽  
pp. 4707-4716 ◽  
Author(s):  
Wei Liu ◽  
Shi Lei Dong ◽  
Fei Xu ◽  
Xue Qin Wang ◽  
T. Ryan Withers ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Growth Conditions ◽  
Anaerobic Growth ◽  
Anaerobic Conditions ◽  
Content Type ◽  
E Coli ◽  
Intracellular Expression ◽  
Aerobic And Anaerobic Growth ◽  
Aerobic And Anaerobic ◽  
Aerobic And Anaerobic Conditions

ABSTRACTAntimicrobial peptides (AMPs) can cause lysis of target bacteria by directly inserting themselves into the lipid bilayer. This killing mechanism confounds the identification of the intracellular targets of AMPs. To circumvent this, we used a shuttle vector containing the inducible expression of a human cathelicidin-related AMP, LL-37, to examine its effect onEscherichia coliTOP10 under aerobic and anaerobic growth conditions. Induction of LL-37 caused growth inhibition and alteration in cell morphology to a filamentous phenotype. Further examination of theE. colicell division protein FtsZ revealed that LL-37 did not interact with FtsZ. Moreover, intracellular expression of LL-37 results in the enhanced production of reactive oxygen species (ROS), causing lethal membrane depolarization under aerobic conditions. Additionally, the membrane permeability was increased after intracellular expression of LL37 under both aerobic and anaerobic conditions. Transcriptomic analysis revealed that intracellular LL-37 mainly affected the expression of genes related to energy production and carbohydrate metabolism. More specifically, genes related to oxidative phosphorylation under both aerobic and anaerobic growth conditions were affected. Collectively, our current study demonstrates that intracellular expression of LL-37 inE. colican inhibit growth under aerobic and anaerobic conditions. While we confirmed that the generation of ROS is a bactericidal mechanism for LL-37 under aerobic growth conditions, we also found that the intracellular accumulation of cationic LL-37 influences the redox and ion status of the cells under both growth conditions. These data suggest that there is a new AMP-mediated bacterial killing mechanism that targets energy metabolism.

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