scholarly journals Activation by nitric oxide of an oxidative-stress response that defends Escherichia coli against activated macrophages.

1993 ◽  
Vol 90 (21) ◽  
pp. 9993-9997 ◽  
Author(s):  
T. Nunoshiba ◽  
T. deRojas-Walker ◽  
J. S. Wishnok ◽  
S. R. Tannenbaum ◽  
B. Demple
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Escherichia Coli ◽  
Stress Response ◽  
Oxidative Stress Response ◽  
Activated Macrophages

scholarly journals Gonadal Steroids Negatively Modulate Oxidative Stress in CBA/Ca Female Mice Infected withP. bergheiANKA

2014 ◽  
Vol 2014 ◽  
pp. 1-10 ◽  
Author(s):  
Néstor Aarón Mosqueda-Romo ◽  
Ana Laura Rodríguez-Morales ◽  
Fidel Orlando Buendía-González ◽  
Margarita Aguilar-Sánchez ◽  
Jorge Morales-Montor ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Nitric Oxide ◽  
Superoxide Dismutase ◽  
Sexual Dimorphism ◽  
Stress Response ◽  
Glutathione Peroxidase ◽  
Oxidative Stress Response ◽  
Gonadal Steroids ◽  
Male Mice ◽  
Female Mice

We decreased the level of gonadal steroids in female and male mice by gonadectomy. We infected these mice withP. bergheiANKA and observed the subsequent impact on the oxidative stress response. Intact females developed lower levels of parasitaemia and lost weight faster than intact males. Gonadectomised female mice displayed increased levels of parasitaemia, increased body mass, and increased anaemia compared with their male counterparts. In addition, gonadectomised females exhibited lower specific catalase, superoxide dismutase, and glutathione peroxidase activities in their blood and spleen tissues compared with gonadectomised males. To further study the oxidative stress response inP. bergheiANKA-infected gonadectomised mice, nitric oxide levels were assessed in the blood and spleen, and MDA levels were assessed in the spleen. Intact, sham-operated, and gonadectomised female mice exhibited higher levels of nitric oxide in the blood and spleen compared with male mice. MDA levels were higher in all of the female groups. Finally, gonadectomy significantly increased the oxidative stress levels in females but not in males. These data suggest that differential oxidative stress is influenced by oestrogens that may contribute to sexual dimorphism in malaria.

scholarly journals Escherichia coli K-12 YfgF is an anaerobic cyclic di-GMP phosphodiesterase with roles in cell surface remodelling and the oxidative stress response

Microbiology ◽  
2010 ◽  
Vol 156 (9) ◽  
pp. 2873-2886 ◽  
Author(s):  
Melissa M. Lacey ◽  
Jonathan D. Partridge ◽  
Jeffrey Green
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Stress Response ◽  
Cell Surface ◽  
Regulatory Networks ◽  
Oxidative Stress Response ◽  
Cyclase Activity ◽  
Diguanylate Cyclase ◽  
Phosphodiesterase Activity ◽  
K 12

The Escherichia coli K-12 yfgF gene encodes a protein with domains associated with cyclic di-GMP signalling: GGDEF (associated with diguanylate cyclase activity) and EAL (associated with cyclic di-GMP phosphodiesterase activity). Here, it is shown that yfgF is expressed under anaerobic conditions from a class II FNR (regulator of fumarate and nitrate reduction)-dependent promoter. Anaerobic expression of yfgF is greatest in stationary phase, and in cultures grown at 28 °C, suggesting that low growth rates promote yfgF expression. Mutation of yfgF resulted in altered cell surface properties and enhanced sensitivity when anaerobic cultures were exposed to peroxides. The purified YfgF GGDEF-EAL (YfgFGE) and EAL (YfgFE) domains possessed cyclic di-GMP-specific phosphodiesterase activity, but lacked diguanylate cyclase activity. However, the catalytically inactive GGDEF domain was required for YfgFGE dimerization and enhanced cyclic di-GMP phosphodiesterase activity in the presence of physiological concentrations of Mg2+. The cyclic di-GMP phosphodiesterase activity of YfgFGE and YfgFE was inhibited by the product of the reaction, 5′-phosphoguanylyl-(3′–5′)-guanosine (pGpG). Thus, it is shown that the yfgF gene encodes an anaerobic cyclic di-GMP phosphodiesterase that is involved in remodelling the cell surface of E. coli K-12 and in the response to peroxide shock, with implications for integrating three global regulatory networks, i.e. oxygen regulation, cyclic di-GMP signalling and the oxidative stress response.

scholarly journals Increasing the Oxidative Stress Response Allows Escherichia coli To Overcome Inhibitory Effects of Condensed Tannins

2003 ◽  
Vol 69 (6) ◽  
pp. 3406-3411 ◽  
Author(s):  
Alexandra H. Smith ◽  
James A. Imlay ◽  
Roderick I. Mackie
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Stress Response ◽  
Condensed Tannins ◽  
Resistant Mutant ◽  
Inhibitory Effect ◽  
Oxidative Stress Response ◽  
Inhibitory Effects ◽  
Acacia Mearnsii ◽  
E Coli

ABSTRACT Tannins are plant-derived polyphenols with antimicrobial effects. The mechanism of tannin toxicity towards Escherichia coli was determined by using an extract from Acacia mearnsii (Black wattle) as a source of condensed tannins (proanthocyanidins). E. coli growth was inhibited by tannins only when tannins were exposed to oxygen. Tannins auto-oxidize, and substantial hydrogen peroxide was generated when they were added to aerobic media. The addition of exogenous catalase permitted growth in tannin medium. E. coli mutants that lacked HPI, the major catalase, were especially sensitive to tannins, while oxyR mutants that constitutively overexpress antioxidant enzymes were resistant. A tannin-resistant mutant was isolated in which a promoter-region point mutation increased the level of HPI by 10-fold. Our results indicate that wattle condensed tannins are toxic to E. coli in aerobic medium primarily because they generate H2O2. The oxidative stress response helps E. coli strains to overcome their inhibitory effect.

scholarly journals 3-phenylpropionate catabolism and the Escherichia coli oxidative stress response

2005 ◽  
Vol 156 (3) ◽  
pp. 312-321 ◽  
Author(s):  
Evelyne Turlin ◽  
Odile Sismeiro ◽  
Jean Pierre Le Caer ◽  
Valérie Labas ◽  
Antoine Danchin ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Escherichia Coli ◽  
Stress Response ◽  
Oxidative Stress Response
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