scholarly journals Studies on the Accumulation of Putrescine and Spermidine in Escherichia coli

1985 ◽  
Vol 38 (4) ◽  
pp. 383
Author(s):  
AJ Smigielski ◽  
ME Muir ◽  
BJ Wallace
Keyword(s):  
High Energy ◽  
Proton Motive Force ◽  
Metabolic Energy ◽  
Uptake System ◽  
Anaerobic Conditions ◽  
High Dilution ◽  
E Coli ◽  
Chemostat Cultures ◽  
Slow Growing ◽  
Rate Of Accumulation

The rate of accumulation of the polyamines spermidine and putrescine by E. coli depended on growth rate. Spermidine ac~umulation was faster in chemostat cultures with high dilution rates than in those with low dilution rates and was slower in bacteria that had been grown for several generations with either putrescine or spermidine, suggesting that the spermidine-uptake system was repressed by exogenous polyamines. The uptake of spermidine required metabolic energy. Thus accumulation occurred in an energy-starved unc strain only upon addition of glucose (or D-lactate to a smaller extent). With glucose present accumulation occurred in an unc, frd strain under anaerobic conditions, suggesting that ATP drives uptake. However, accumulation was generally sensitive to carbonylcyanide m-chlorophenylhydrazone (CCCP), indicating that the proton motive force was involved in uptake. Unlike spermidine, putrescine accumulation was faster in slow-growing than in fast-growing cultures. This may have been due to greater efflux of putrescine at faster growth rates. Accumulation of putrescine was faster following prolonged growth with either putrescine or spermidine, suggesting induction of the putrescine-uptake system by exogenous polyamines. Like spermidine accumulation, putrescine accumulation required metabolic energy. Accumulation was insensitive to CCCP and occurred only when glucose was added to energy-starved unc bacteria, suggesting that high-energy bonds may drive the uptake of putrescine.

scholarly journals Energy Metabolism of Human Leukemic Lymphocytes and Granulocytes

Blood ◽  
1967 ◽  
Vol 30 (2) ◽  
pp. 151-167 ◽  
Author(s):  
JOHN LASZLO ◽  
Clarence Ellis
Keyword(s):  
Energy Metabolism ◽  
Chronic Lymphocytic Leukemia ◽  
Glucose Concentration ◽  
Acute Lymphocytic Leukemia ◽  
Aerobic Glycolysis ◽  
High Energy ◽  
Lymphocytic Leukemia ◽  
Anaerobic Conditions ◽  
High Energy Phosphate

Abstract 1. Leukocytes taken from patients having acute lymphocytic leukemia and chronic lymphocytic leukemia are characterized by high respiratory rates and low to absent aerobic glycolysis. Leukemic granulocytes have low respiratory rates and high aerobic glycolysis. 2. Lymphocytes and granulocytes have the capacity for high glycolytic rates under anaerobic conditions. 3. Lymphocyte respiration is independent of glucose concentration in contrast to granulocyte respiration. 4. High energy phosphate levels of lymphocytes and granulocytes are unchanged if these cells are incubated aerobically, either with or without glucose, or anaerobically in the presence of glucose. 5. Aerobic glycolysis can be induced in lymphocytes by the addition of foreign plasma. Foreign plasma may also alter granulocyte metabolism.

Potentiation by L-cysteine of the bactericidal effect of hydrogen peroxide in Escherichia coli

1982 ◽  
Vol 152 (1) ◽  
pp. 81-88
Author(s):  
E H Berglin ◽  
M B Edlund ◽  
G K Nyberg ◽  
J Carlsson
Keyword(s):  
Escherichia Coli ◽  
Hydrogen Peroxide ◽  
Metal Ion ◽  
Chelating Agent ◽  
Fold Increase ◽  
Bactericidal Effect ◽  
Anaerobic Conditions ◽  
Dna Breakage ◽  
E Coli ◽  
K 12

Under anaerobic conditions an exponentially growing culture of Escherichia coli K-12 was exposed to hydrogen peroxide in the presence of various compounds. Hydrogen peroxide (0.1 mM) together with 0.1 mM L-cysteine or L-cystine killed the organisms more rapidly than 10 mM hydrogen peroxide alone. The exposure of E. coli to hydrogen peroxide in the presence of L-cysteine inhibited some of the catalase. This inhibition, however, could not fully explain the 100-fold increase in hydrogen peroxide sensitivity of the organism in the presence of L-cysteine. Of other compounds tested only some thiols potentiated the bactericidal effect of hydrogen peroxide. These thiols were effective, however, only at concentrations significantly higher than 0.1 mM. The effect of L-cysteine and L-cystine could be annihilated by the metal ion chelating agent 2,2'-bipyridyl. DNA breakage in E. coli K-12 was demonstrated under conditions where the organisms were killed by hydrogen peroxide.

scholarly journals Effects of Dinitrophenol and Oligomycin on the Coupling between Anaerobic Metabolism and Anaerobic Sodium Transport by the Isolated Turtle Bladder

1966 ◽  
Vol 49 (3) ◽  
pp. 483-499 ◽  
Author(s):  
Neal S. Bricker ◽  
Saulo Klahr
Keyword(s):  
Sodium Transport ◽  
Anaerobic Metabolism ◽  
Sodium Pump ◽  
High Energy ◽  
Mitochondrial Atpase ◽  
Anaerobic Glycolysis ◽  
Anaerobic Conditions ◽  
Na Transport ◽  
Anaerobic System ◽  
Mitochondrial Atpase Activity

Dinitrophenol (1 x 10-5 M) has been found to inhibit anaerobic sodium transport by the isolated urinary bladder of the fresh water turtle. Concurrently, anaerobic glycolysis was stimulated markedly. However, tissue ATP levels diminished only modestly, remaining at approximately 75% of values observed under anaerobic conditions without DNP. The utilization of glucose (from endogenous glycogen) corresponded closely to that predicted from the molar quantities of lactate formed. Thus the glycolytic pathway was completed in the presence of DNP and if ATP were synthesized normally during glycolysis, synthesis should have been increased. On the other hand, the decrease in Na transport should have decreased ATP utilization. Oligomycin did not block sodium transport either aerobically or anaerobically, but ATP concentrations did decrease. When anaerobic glycolysis was blocked by iodoacetate, pyruvate did not sustain sodium transport thus suggesting that no electron acceptors were available in the system. Two explanations are entertained for the anaerobic effect of DNP: (a) Stimulation by DNP of plasma membrane as well as mitochondrial ATPase activity; (b) inhibition of a high energy intermediate derived from glycolytic ATP or from glycolysis per se. The arguments relevant to each possibility are presented in the text. Although definitive resolution is not possible, we believe that the data favor the hypothesis that there was a high energy intermediate in the anaerobic system and that this intermediate, rather than ATP, served as the immediate source of energy for the sodium pump.

scholarly journals Bacterial growth laws reflect the evolutionary importance of energy efficiency

2014 ◽  
Vol 112 (2) ◽  
pp. 406-411 ◽  
Author(s):  
Arijit Maitra ◽  
Ken A. Dill
Keyword(s):  
Energy Efficiency ◽  
Bacterial Growth ◽  
Growth Conditions ◽  
High Energy ◽  
Fast Growth ◽  
Growth Speed ◽  
Energy Costs ◽  
Extensive Literature ◽  
E Coli ◽  
Growth Laws

We are interested in the balance of energy and protein synthesis in bacterial growth. How has evolution optimized this balance? We describe an analytical model that leverages extensive literature data on growth laws to infer the underlying fitness landscape and to draw inferences about what evolution has optimized inEscherichia coli. IsE. colioptimized for growth speed, energy efficiency, or some other property? Experimental data show that at its replication speed limit,E. coliproduces about four mass equivalents of nonribosomal proteins for every mass equivalent of ribosomes. This ratio can be explained if the cell’s fitness function is the the energy efficiency of cells under fast growth conditions, indicating a tradeoff between the high energy costs of ribosomes under fast growth and the high energy costs of turning over nonribosomal proteins under slow growth. This model gives insight into some of the complex nonlinear relationships between energy utilization and ribosomal and nonribosomal production as a function of cell growth conditions.

scholarly journals Blue light is a universal tactic signal forEscherichia coli

2017 ◽  
Author(s):  
Tatyana Perlova ◽  
Martin Gruebele ◽  
Yann R. Chemla
Keyword(s):  
Blue Light ◽  
Light Exposure ◽  
Biological Significance ◽  
Proton Motive Force ◽  
Motive Force ◽  
Swimming Velocity ◽  
Bacterial Strains ◽  
E Coli ◽  
Before And After ◽  
Swimming Bacteria

AbstractBlue light has been shown to elicit a tumbling response inE. coli, a non-phototrophic bacterium. The exact mechanism of this phototactic response is still unknown, and its biological significance remains unclear. Here, we quantify phototaxis inE. coliby analyzing single-cell trajectories in populations of free-swimming bacteria before and after light exposure. Bacterial strains expressing only one type of chemoreceptor reveal that all fiveE. colireceptors - Aer, Tar, Tsr, Tap and Trg - are capable of mediating a response to light. In particular, light exposure elicits a running response in Tap-only strain, the opposite of the tumbling response observed for all other strains. Light therefore emerges as a universal stimulus for allE. colichemoreceptors. We also show that blue light exposure causes a reversible decrease in swimming velocity, a proxy for proton motive force. We hypothesize that rather than sensing light directly, chemoreceptors sense light-induced perturbations in proton motive force.ImportanceOur findings provide new insights on the mechanism ofE. coliphototaxis, showing that all five chemoreceptor types respond to light and that their interactions play an important role in cell behavior. Our results also open up new avenues for examining and manipulatingE. colitaxis. Since light is a universal stimulus, it may provide a way to quantify interactions between different types of receptors. Since light is easier to control spatially and temporally than chemicals, it may be used to study swimming behavior in complex environments. Since phototaxis can cause migration ofE. colibacteria in light gradients, light may be used to control bacterial density for studying density-dependent processes in bacteria.

scholarly journals Ferric Citrate Uptake is a Virulence Factor in Uropathogenic Escherichia coli

2021 ◽  
Author(s):  
Arwen E Frick-Cheng ◽  
Anna Sintsova ◽  
Sara N Smith ◽  
Ali Pirani ◽  
Evan S Snitkin ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Urinary Tract ◽  
Iron Acquisition ◽  
Uropathogenic Escherichia Coli ◽  
Ferric Citrate ◽  
Uptake System ◽  
Lipocalin 2 ◽  
Compensatory Mechanisms ◽  
E Coli ◽  
Iron Source

More than half of women will experience a urinary tract infection (UTI) with uropathogenic Escherichia coli (UPEC) causing ~80% of uncomplicated cases. Iron acquisition systems are essential for uropathogenesis, and UPEC encode functionally redundant iron acquisition systems, underlining their importance. However, a recent UPEC clinical isolate, HM7 lacks this functional redundancy and instead encodes a sole siderophore, enterobactin. To determine if E. coli HM7 possesses unidentified iron acquisition systems, we performed RNA-sequencing under iron-limiting conditions and demonstrated that the ferric citrate uptake system (fecABCDE and fecIR) was highly upregulated. Importantly, there are high levels of citrate within urine, some of which is bound to iron, and the fec system is highly enriched in UPEC isolates compared to environmental or fecal strains. Therefore, we hypothesized that HM7 and other similar strains use the fec system to acquire iron in the host. Deletion of both enterobactin biosynthesis and ferric citrate uptake (ΔentB/ΔfecA) abrogates use of ferric citrate as an iron source and fecA provides an advantage in human urine in absence of enterobactin. However, in a UTI mouse model, fecA is a fitness factor independent of enterobactin production, likely due to the action of host Lipocalin-2 chelating ferrienterobactin. These findings indicate that ferric citrate uptake is used as an iron source when siderophore efficacy is limited, such as in the host during UTI. Defining these novel compensatory mechanisms and understanding the nutritional hierarchy of preferred iron sources within the urinary tract are important in the search for new approaches to combat UTI.

scholarly journals Biocatalyst Engineering by Assembly of Fatty Acid Transport and Oxidation Activities for In Vivo Application of Cytochrome P-450BM-3 Monooxygenase

1998 ◽  
Vol 64 (10) ◽  
pp. 3784-3790 ◽  
Author(s):  
Silke Schneider ◽  
Marcel G. Wubbolts ◽  
Dominique Sanglard ◽  
Bernard Witholt
Keyword(s):  
Fatty Acids ◽  
Fatty Acid ◽  
Coenzyme A ◽  
Fatty Acid Uptake ◽  
Acid Uptake ◽  
Uptake System ◽  
Whole Cells ◽  
E Coli ◽  
Cytochrome P 450 ◽  
Long Chain

ABSTRACT The application of whole cells containing cytochrome P-450BM-3 monooxygenase [EC 1.14.14.1 ] for the bioconversion of long-chain saturated fatty acids to ω-1, ω-2, and ω-3 hydroxy fatty acids was investigated. We utilized pentadecanoic acid and studied its conversion to a mixture of 12-, 13-, and 14-hydroxypentadecanoic acids by this monooxygenase. For this purpose,Escherichia coli recombinants containing plasmid pCYP102 producing the fatty acid monooxygenase cytochrome P-450BM-3were used. To overcome inefficient uptake of pentadecanoic acid by intact E. coli cells, we made use of a cloned fatty acid uptake system from Pseudomonas oleovorans which, in contrast to the common FadL fatty acid uptake system of E. coli, does not require coupling by FadD (acyl-coenzyme A synthetase) of the imported fatty acid to coenzyme A. This system fromP. oleovorans is encoded by a gene carried by plasmid pGEc47, which has been shown to effect facilitated uptake of oleic acid in E. coli W3110 (M. Nieboer, Ph.D. thesis, University of Groningen, Groningen, The Netherlands, 1996). By using a double recombinant of E. coli K27, which is a fadDmutant and therefore unable to consume substrates or products via the β-oxidation cycle, a twofold increase in productivity was achieved. Applying cytochrome P-450BM-3 monooxygenase as a biocatalyst in whole cells does not require the exogenous addition of the costly cofactor NADPH. In combination with the coenzyme A-independent fatty acid uptake system from P. oleovorans, cytochrome P-450BM-3 recombinants appear to be useful alternatives to the enzymatic approach for the bioconversion of long-chain fatty acids to subterminal hydroxylated fatty acids.

scholarly journals Prevalence of the “High-Pathogenicity Island” of Yersinia Species among Escherichia coliStrains That Are Pathogenic to Humans

1998 ◽  
Vol 66 (2) ◽  
pp. 480-485 ◽  
Author(s):  
S. Schubert ◽  
A. Rakin ◽  
H. Karch ◽  
E. Carniel ◽  
J. Heesemann
Keyword(s):  
Gene Cluster ◽  
Yersinia Pseudotuberculosis ◽  
Pathogenicity Island ◽  
Uptake System ◽  
Highly Pathogenic ◽  
E Coli ◽  
Yersinia Species ◽  
The Family ◽  
High Pathogenicity ◽  
Dna Sequence Comparison

ABSTRACT The fyuA-irp gene cluster contributes to the virulence of highly pathogenic Yersinia (Yersinia pestis,Yersinia pseudotuberculosis, and Yersinia enterocolitica 1B). The cluster encodes an iron uptake system mediated by the siderophore yersiniabactin and reveals features of a pathogenicity island. Two evolutionary lineages of this “high pathogenicity island” (HPI) can be distinguished on the basis of DNA sequence comparison: a Y. pestis group and a Y. enterocolitica group. In this study we demonstrate that the HPI of the Y. pestis evolutionary group is disseminated among species of the family Enterobacteriaceae which are pathogenic to humans. It prevails in enteroaggregativeEscherichia coli and in E. coli blood culture isolates (93 and 80%, respectively), but is rarely found in enteropathogenic E. coli, enteroinvasive E. coli, and enterotoxigenic E. coli isolates. In contrast, the HPI was absent from enterohemorrhagic E. coli, Shigella, and Salmonella entericastrains investigated. Polypeptides encoded by the fyuA,irp1, and irp2 genes located on the HPI could be detected in E. coli strains pathogenic to humans. However, these E. coli strains showed a reduced sensitivity to the bacteriocin pesticin, whose uptake is mediated by the FyuA receptor. Escherichia strains do not possess thehms gene locus thought to be a part of the HPI of Y. pestis. Deletions of the fyuA-irp gene cluster affecting solely the fyuA part of the HPI were identified in 3% of the E. coli strains tested. These results suggest horizontal transfer of the HPI between Y. pestis and some pathogenic E. coli strains.

scholarly journals Mechanism of Bactericidal Activity of Microcin L inEscherichia coliandSalmonella enterica

2010 ◽  
Vol 55 (3) ◽  
pp. 997-1007 ◽  
Author(s):  
Natacha Morin ◽  
Isabelle Lanneluc ◽  
Nathalie Connil ◽  
Marie Cottenceau ◽  
Anne Marie Pons ◽  
...  
Keyword(s):  
Outer Membrane ◽  
Bactericidal Activity ◽  
Salmonella Enterica ◽  
Cytoplasmic Membrane ◽  
Genetic System ◽  
Proton Motive Force ◽  
Motive Force ◽  
Membrane Properties ◽  
Outer Membrane Receptor ◽  
E Coli

ABSTRACTFor the first time, the mechanism of action of microcin L (MccL) was investigated in live bacteria. MccL is a gene-encoded peptide produced byEscherichia coliLR05 that exhibits a strong antibacterial activity against relatedEnterobacteriaceae, includingSalmonella entericaserovars Typhimurium and Enteritidis. We first subcloned the MccL genetic system to remove the sequences not involved in MccL production. We then optimized the MccL purification procedure to obtain large amounts of purified microcin to investigate its antimicrobial and membrane properties. We showed that MccL did not induce outer membrane permeabilization, which indicated that MccL did not use this way to kill the sensitive cell or to enter into it. Using a set ofE. coliandSalmonella entericamutants lacking iron-siderophore receptors, we demonstrated that the MccL uptake required the outer membrane receptor Cir. Moreover, the MccL bactericidal activity was shown to depend on the TonB protein that transduces the proton-motive force of the cytoplasmic membrane to transport iron-siderophore complexes across the outer membrane. Using carbonyl cyanide 3-chlorophenylhydrazone, which is known to fully dissipate the proton-motive force, we proved that the proton-motive force was required for the bactericidal activity of MccL onE. coli. In addition, we showed that a primary target of MccL could be the cytoplasmic membrane: a high level of MccL disrupted the inner membrane potential ofE. colicells. However, no permeabilization of the membrane was detected.

scholarly journals Redesigning Escherichia coli Metabolism for Anaerobic Production of Isobutanol

2011 ◽  
Vol 77 (14) ◽  
pp. 4894-4904 ◽  
Author(s):  
Cong T. Trinh ◽  
Johnny Li ◽  
Harvey W. Blanch ◽  
Douglas S. Clark
Keyword(s):  
Escherichia Coli ◽  
Anaerobic Growth ◽  
Mode Analysis ◽  
Glycolytic Flux ◽  
Strictly Anaerobic ◽  
Anaerobic Conditions ◽  
Content Type ◽  
E Coli ◽  
Model Predictions ◽  
Chromosomal Genes

ABSTRACTFermentation enables the production of reduced metabolites, such as the biofuels ethanol and butanol, from fermentable sugars. This work demonstrates a general approach for designing and constructing a production host that uses a heterologous pathway as an obligately fermentative pathway to produce reduced metabolites, specifically, the biofuel isobutanol. Elementary mode analysis was applied to design anEscherichia colistrain optimized for isobutanol production under strictly anaerobic conditions. The central metabolism ofE. coliwas decomposed into 38,219 functional, unique, and elementary modes (EMs). The model predictions revealed that during anaerobic growthE. colicannot produce isobutanol as the sole fermentative product. By deleting 7 chromosomal genes, the total 38,219 EMs were constrained to 12 EMs, 6 of which can produce high yields of isobutanol in a range from 0.29 to 0.41 g isobutanol/g glucose under anaerobic conditions. The remaining 6 EMs rely primarily on the pyruvate dehydrogenase enzyme complex (PDHC) and are typically inhibited under anaerobic conditions. The redesignedE. colistrain was constrained to employ the anaerobic isobutanol pathways through deletion of 7 chromosomal genes, addition of 2 heterologous genes, and overexpression of 5 genes. Here we present the design, construction, and characterization of an isobutanol-producingE. colistrain to illustrate the approach. The model predictions are evaluated in relation to experimental data and strategies proposed to improve anaerobic isobutanol production. We also show that the endogenous alcohol/aldehyde dehydrogenase AdhE is the key enzyme responsible for the production of isobutanol and ethanol under anaerobic conditions. The glycolytic flux can be controlled to regulate the ratio of isobutanol to ethanol production.

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