scholarly journals KatP contributes to OxyR-regulated hydrogen peroxide resistance in Escherichia coli serotype O157 : H7

Microbiology ◽  
2009 ◽  
Vol 155 (11) ◽  
pp. 3589-3598 ◽  
Author(s):  
Gaylen A. Uhlich
Keyword(s):  
Escherichia Coli ◽  
Oxidative Damage ◽  
Physiological Role ◽  
Deletion Strain ◽  
Lag Phase ◽  
Dependent Manner ◽  
E Coli ◽  
Mutant Strains ◽  
Catalase Peroxidase ◽  
K 12

Escherichia coli K-12 defends itself against peroxide-mediated oxidative damage using two catalases, KatG and KatE, and the peroxiredoxin, alkyl hydroperoxide reductase, encoded by ahpC. In E. coli O157 : H7 strain ATCC 43895 (EDL933), plasmid pO157 carries an additional catalase-peroxidase gene, katP. KatP has been shown to be a functional catalase-peroxidase. However, deletion of pO157 does not alter the peroxide resistance of strain EDL933, leaving the physiological role of katP unclear. To examine the individual roles of peroxide-resistance genes in E. coli O157 : H7, mutant strains of ATCC 43895 were constructed bearing individual deletions of katG, katE, katP and ahpC, as well as double, triple and quadruple deletions encompassing all possible gene combinations thereof. The wild-type and all 15 mutant strains were compared for differences in aerobic growth, ability to scavenge exogenous H2O2 and resistance to exogenous peroxides. Although KatG scavenged the most exogenous H2O2, KatP scavenged statistically greater amounts than either KatE or AhpC during exponential growth. However, katG and ahpC together were sufficient for full peroxide resistance in disc diffusion assays. Strains with only katG or ahpC were the only triple deletion strains with significantly shorter generation times than the quadruple deletion strain. ahpC was the only gene that could allow rapid transition from lag phase to exponential phase in a triple deletion strain. Gene expression studies revealed that katP is an OxyR-regulated gene, but its expression is suppressed in stationary phase by RpoS. These studies indicate that pO157-borne katP contributes to the complex gene network protecting strain 43895 from peroxide-mediated oxidative damage in an OxyR-dependent manner.

scholarly journals The yliA, -B, -C, and -D Genes of Escherichia coli K-12 Encode a Novel Glutathione Importer with an ATP-Binding Cassette

2005 ◽  
Vol 187 (17) ◽  
pp. 5861-5867 ◽  
Author(s):  
Hideyuki Suzuki ◽  
Takashi Koyanagi ◽  
Shunsuke Izuka ◽  
Akiko Onishi ◽  
Hidehiko Kumagai
Keyword(s):  
Escherichia Coli ◽  
Atp Binding ◽  
Sulfur Source ◽  
Dependent Manner ◽  
Oxygen Species ◽  
E Coli ◽  
Living Organisms ◽  
K 12 ◽  
Atp Binding Cassette

ABSTRACT Glutathione protects cells and organisms from oxygen species and peroxides and is indispensable for aerobically living organisms. Moreover, it acts against xenobiotics and drugs by the formation and excretion of glutathione S conjugates. In this study, we show that the yliA, -B, -C, and -D genes of Escherichia coli K-12 encode a glutathione transporter with the ATP-binding cassette. The transporter imports extracellular glutathione into the cytoplasm in an ATP-dependent manner. This transporter, along with γ-glutamyltranspeptidase, has an important role in E. coli growth with glutathione as a sole sulfur source.

scholarly journals The energy-linked transhydrogenase reaction in respiratory mutants of Escherichia coli K 12

1971 ◽  
Vol 125 (2) ◽  
pp. 489-493 ◽  
Author(s):  
G. B. Cox ◽  
N. A. Newton ◽  
J. D. Butlin ◽  
F. Gibson
Keyword(s):  
Escherichia Coli ◽  
Energy Source ◽  
Electron Transport ◽  
Electron Transport Chain ◽  
Adenosine Triphosphatase ◽  
E Coli ◽  
Transport Chain ◽  
Mutant Strains ◽  
K 12 ◽  
A Site

1. Energy-linked and non-energy-linked transhydrogenase activities were assayed in membrane preparations from normal Escherichia coli K 12 and from various mutant strains. 2. The energy-linked transhydrogenase, which uses ATP as energy source, was dependent for activity on the presence of a functional Mg2++Ca2+-stimulated adenosine triphosphatase. 3. Neither of the quinones formed by E. coli, namely ubiquinone-8 and menaquinone-8, was required for normal ATP-dependent energy-linked transhydrogenase activity. 4. The energy-linked transhydrogenase was inhibited by piericidin A at a site unrelated to the sites of inhibition of the electron-transport chain by piericidin A.

scholarly journals OmpT Outer Membrane Proteases of Enterohemorrhagic and Enteropathogenic Escherichia coli Contribute Differently to the Degradation of Human LL-37

2011 ◽  
Vol 80 (2) ◽  
pp. 483-492 ◽  
Author(s):  
Jenny-Lee Thomassin ◽  
John R. Brannon ◽  
Bernard F. Gibbs ◽  
Samantha Gruenheid ◽  
Hervé Le Moual
Keyword(s):  
Escherichia Coli ◽  
Outer Membrane ◽  
Time Course ◽  
Dependent Manner ◽  
Content Type ◽  
Reading Frame ◽  
E Coli ◽  
Food Borne ◽  
Mutant Strains

ABSTRACTEnterohemorrhagicEscherichia coli(EHEC) and enteropathogenicE. coli(EPEC) are food-borne pathogens that cause serious diarrheal diseases. To colonize the human intestine, these pathogens must overcome innate immune defenses such as antimicrobial peptides (AMPs). Bacterial pathogens have evolved various mechanisms to resist killing by AMPs, including proteolytic degradation of AMPs. To examine the ability of the EHEC and EPEC OmpT outer membrane (OM) proteases to degrade α-helical AMPs,ompTdeletion mutants were generated. Determination of MICs of various AMPs revealed that both mutant strains are more susceptible than their wild-type counterparts to α-helical AMPs, although to different extents. Time course assays monitoring the degradation of LL-37 and C18G showed that EHEC cells degraded both AMPs faster than EPEC cells in an OmpT-dependent manner. Mass spectrometry analyses of proteolytic fragments showed that EHEC OmpT cleaves LL-37 at dibasic sites. The superior protection provided by EHEC OmpT compared to EPEC OmpT against α-helical AMPs was due to higher expression of theompTgene and, in turn, higher levels of the OmpT protein in EHEC. Fusion of the EPECompTpromoter to the EHECompTopen reading frame resulted in decreased OmpT expression, indicating that transcriptional regulation ofompTis different in EHEC and EPEC. We hypothesize that the different contributions of EHEC and EPEC OmpT to the degradation and inactivation of LL-37 may be due to their adaptation to their respective niches within the host, the colon and small intestine, respectively, where the environmental cues and abundance of AMPs are different.

Biotin auxotrophs of Escherichia coli

1969 ◽  
Vol 15 (1) ◽  
pp. 21-26 ◽  
Author(s):  
C. H. Pai
Keyword(s):  
Escherichia Coli ◽  
Growth Medium ◽  
Biosynthetic Pathway ◽  
Growth Response ◽  
E Coli ◽  
The Third ◽  
Feeding Experiments ◽  
Linear Sequence ◽  
Mutant Strains ◽  
K 12

Biotin-requiring mutants have been isolated from Escherichia coli K-12 and classified into four nutritional groups on the basis of their responses to various biotin vitamers, the ability to feed other mutant strains, and the nature of vitamers excreted into the growth medium. The growth response of the mutant strains to various biotin vitamers was in a linear sequence starting from 7-keto-8-aminopelargonic acid to 7,8-diaminopelargonic acid, to desthiobiotin, and to biotin. From the results of the cross-feeding experiments the excretion of three types of vitamers was indicated and two of the vitamers were identified as desthiobiotin and 7-keto-8-aminopelargonic acid. The third vitamer could not be detected by bio-autographic technique. From these results a biosynthetic pathway of biotin in E. coli has been proposed.

scholarly journals Defective O-Antigen Polymerization in tolA and pal Mutants of Escherichia coli in Response to Extracytoplasmic Stress

2005 ◽  
Vol 187 (10) ◽  
pp. 3359-3368 ◽  
Author(s):  
Enrique D. Vinés ◽  
Cristina L. Marolda ◽  
Aran Balachandran ◽  
Miguel A. Valvano
Keyword(s):  
Escherichia Coli ◽  
Stress Response ◽  
Stress Responses ◽  
Surface Expression ◽  
Dependent Manner ◽  
E Coli ◽  
O Antigen ◽  
O Antigens ◽  
K 12 ◽  
Reduced Surface

ABSTRACT We have previously shown that the TolA protein is required for the correct surface expression of the Escherichia coli O7 antigen lipopolysaccharide (LPS). In this work, ΔtolA and Δpal mutants of E. coli K-12 W3110 were transformed with pMF19 (encoding a rhamnosyltransferase that reconstitutes the expression of O16-specific LPS), pWQ5 (encoding the Klebsiella pneumoniae O1 LPS gene cluster), or pWQ802 (encoding the genes necessary for the synthesis of Salmonella enterica O:54). Both ΔtolA and Δpal mutants exhibited reduced surface expression of O16 LPS as compared to parental W3110, but no significant differences were observed in the expression of K. pneumoniae O1 LPS and S. enterica O:54 LPS. Therefore, TolA and Pal are required for the correct surface expression of O antigens that are assembled in a wzy (polymerase)-dependent manner (like those of E. coli O7 and O16) but not for O antigens assembled by wzy-independent pathways (like K. pneumoniae O1 and S. enterica O:54). Furthermore, we show that the reduced surface expression of O16 LPS in ΔtolA and Δpal mutants was associated with a partial defect in O-antigen polymerization and it was corrected by complementation with intact tolA and pal genes, respectively. Using derivatives of W3110ΔtolA and W3110Δpal containing lacZ reporter fusions to fkpA and degP, we also demonstrate that the RpoE-mediated extracytoplasmic stress response is upregulated in these mutants. Moreover, an altered O16 polymerization was also detected under conditions that stimulate RpoE-mediated extracytoplasmic stress responses in tol + and pal + genetic backgrounds. A Wzy derivative with an epitope tag at the C-terminal end of the protein was stable in all the mutants, ruling out stress-mediated proteolysis of Wzy. We conclude that the absence of TolA and Pal elicits a sustained extracytoplasmic stress response that in turn reduces O-antigen polymerization but does not affect the stability of the Wzy O-antigen polymerase.

scholarly journals Deletion of the yiaMNO transporter genes affects the growth characteristics of Escherichia coli K-12

Microbiology ◽  
2005 ◽  
Vol 151 (5) ◽  
pp. 1683-1689 ◽  
Author(s):  
Titia H. Plantinga ◽  
Chris van der Does ◽  
Danuta Tomkiewicz ◽  
Geertje van Keulen ◽  
Wil N. Konings ◽  
...  
Keyword(s):  
Escherichia Coli ◽  
Biofilm Formation ◽  
Sole Carbon Source ◽  
Binding Protein ◽  
Physiological Role ◽  
Proton Motive Force ◽  
Growth Characteristics ◽  
Wild Type ◽  
E Coli ◽  
K 12

Binding-protein-dependent secondary transporters make up a unique transport protein family. They use a solute-binding protein in proton-motive-force-driven transport. Only a few systems have been functionally analysed. The yiaMNO genes of Escherichia coli K-12 encode one family member that transports the rare pentose l-xylulose. Its physiological role is unknown, since wild-type E. coli K-12 does not utilize l-xylulose as sole carbon source. Deletion of the yiaMNO genes in E. coli K-12 strain MC4100 resulted in remarkable changes in the transition from exponential growth to the stationary phase, high-salt survival and biofilm formation.

scholarly journals Structural genes for nitrate-inducible formate dehydrogenase in Escherichia coli K-12.

Genetics ◽  
1990 ◽  
Vol 125 (4) ◽  
pp. 691-702 ◽  
Author(s):  
B L Berg ◽  
V Stewart
Keyword(s):  
Escherichia Coli ◽  
Nitrate Reductase ◽  
Formate Dehydrogenase ◽  
Recombinant Dna ◽  
Structural Genes ◽  
Respiratory Pathway ◽  
E Coli ◽  
Formate Oxidation ◽  
Operon Expression ◽  
K 12

Abstract Formate oxidation coupled to nitrate reduction constitutes a major anaerobic respiratory pathway in Escherichia coli. This respiratory chain consists of formate dehydrogenase-N, quinone, and nitrate reductase. We have isolated a recombinant DNA clone that likely contains the structural genes, fdnGHI, for the three subunits of formate dehydrogenase-N. The fdnGHI clone produced proteins of 110, 32 and 20 kDa which correspond to the subunit sizes of purified formate dehydrogenase-N. Our analysis indicates that fdnGHI is organized as an operon. We mapped the fdn operon to 32 min on the E. coli genetic map, close to the genes for cryptic nitrate reductase (encoded by the narZ operon). Expression of phi(fdnG-lacZ) operon fusions was induced by anaerobiosis and nitrate. This induction required fnr+ and narL+, two regulatory genes whose products are also required for the anaerobic, nitrate-inducible activation of the nitrate reductase structural gene operon, narGHJI. We conclude that regulation of fdnGHI and narGHJI expression is mediated through common pathways.

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.

Antibacterial Effects of Long-Chain Polyphosphates on Selected Spoilage and Pathogenic Bacteria

2008 ◽  
Vol 71 (7) ◽  
pp. 1401-1405 ◽  
Author(s):  
JEREMY A. OBRITSCH ◽  
DOJIN RYU ◽  
LUCINA E. LAMPILA ◽  
LLOYD B. BULLERMAN
Keyword(s):  
Food Industry ◽  
Pathogenic Bacteria ◽  
Antimicrobial Activities ◽  
Lag Phase ◽  
E Coli ◽  
Inhibition Of Growth ◽  
K 12 ◽  
Chain Lengths ◽  
And Staphylococcus Aureus ◽  
Long Chain

The antimicrobial activities of four long-chain food-grade polyphosphates were studied at concentrations allowed in the food industry (<5,000 ppm) in defined basal media by determining the inhibition of growth of three gram-negative and four gram-positive spoilage and pathogenic bacteria. Both generation time and lag phase of Escherichia coli K-12, E. coli O157: H7, and Salmonella Typhimurium were increased with all of the polyphosphates tested. Bacillus subtilis and Staphylococcus aureus were more sensitive to polyphosphates, but not in all cases, with multiphased growth. The growth of Lactobacillus plantarum was inhibited by polyphosphates at concentrations above 750 ppm, but the lag time of Listeria monocytogenes was shortened by the presence of polyphosphates. No single polyphosphate was maximally inhibitory against all bacteria. Polyphosphates with chain lengths of 12 to 15 were significantly different from those with chain lengths of 18 to 21 depending on the organism and concentrations of polyphosphate used. Overall, higher polyphosphate concentrations resulted in greater inhibition of bacterial growth.

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