Faculty Opinions recommendation of Superoxide dismutase activity confers (p)ppGpp-mediated antibiotic tolerance to stationary-phase Pseudomonas aeruginosa.

2018 ◽  
Author(s):  
Adam Duerfeldt ◽  
Nathan Lavey
Keyword(s):  
Pseudomonas Aeruginosa ◽  
Superoxide Dismutase ◽  
Stationary Phase ◽  
Superoxide Dismutase Activity ◽  
Antibiotic Tolerance

scholarly journals Superoxide dismutase activity confers (p)ppGpp-mediated antibiotic tolerance to stationary-phasePseudomonas aeruginosa

2018 ◽  
Vol 115 (39) ◽  
pp. 9797-9802 ◽  
Author(s):  
Dorival Martins ◽  
Geoffrey McKay ◽  
Gowthami Sampathkumar ◽  
Malika Khakimova ◽  
Ann M. English ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Stationary Phase ◽  
Growth Arrest ◽  
Stringent Response ◽  
Antioxidant Defenses ◽  
Antibiotic Tolerance ◽  
Sod Activity ◽  
Downstream Effectors ◽  
Key Factor ◽  
Multidrug Tolerance

Metabolically quiescent bacteria represent a large proportion of those in natural and host environments, and they are often refractory to antibiotic treatment. Such drug tolerance is also observed in the laboratory during stationary phase, when bacteria face stress and starvation-induced growth arrest. Tolerance requires (p)ppGpp signaling, which mediates the stress and starvation stringent response (SR), but the downstream effectors that confer tolerance are unclear. We previously demonstrated that the SR is linked to increased antioxidant defenses inPseudomonas aeruginosa. We now demonstrate that superoxide dismutase (SOD) activity is a key factor in SR-mediated multidrug tolerance in stationary-phaseP. aeruginosa. Inactivation of the SR leads to loss of SOD activity and decreased multidrug tolerance during stationary phase. Genetic or chemical complementation of SOD activity of theΔrelA spoTmutant (ΔSR) is sufficient to restore antibiotic tolerance to WT levels. Remarkably, we observe high membrane permeability and increased drug internalization upon ablation of SOD activity. Combined, our results highlight an unprecedented mode of SR-mediated multidrug tolerance in stationary-phaseP. aeruginosaand suggest that inhibition of SOD activity may potentiate current antibiotics.

scholarly journals Biosynthesis of oxygen-detoxifying enzymes in Bdellovibrio stolpii

1982 ◽  
Vol 152 (2) ◽  
pp. 792-796
Author(s):  
R S Von Stein ◽  
L E Barber ◽  
H M Hassan
Keyword(s):  
Superoxide Dismutase ◽  
Stationary Phase ◽  
Protein Biosynthesis ◽  
Oxygen Toxicity ◽  
Enzyme Synthesis ◽  
Maximum Activity ◽  
Superoxide Dismutase Activity ◽  
Detoxifying Enzymes ◽  
Major Band ◽  
Kinetics Of

Axenically grown Bdellovibrio stolpii (i.e., grown independently of the host) was examined for superoxide dismutase, catalase, and peroxidase activities. Kinetics of enzyme synthesis were determined for aerobically grown cultures and for cultures exposed to 100% oxygen. Enzymatic activities varied with the age of the culture. Normally grown cultures exhibited maximum activity during the first 10 h of growth and again as the stationary phase was approached, beginning at about 48 h. Polyacrylamide gel electropherograms of cell-free extracts revealed that B. stolpii contained one major band (1) and two minor bands (II, III) of superoxide dismutase activity. Each of these enzymes was inactivated by H2O2, indicating that they were iron-containing enzymes. Manganese-containing superoxide dismutase was not detected in B. stolpii. Increased oxygenation did not appreciably stimulate enzyme synthesis, for only superoxide dismutase was induced, reaching maximum activity at 10 h and then rapidly falling to normal levels. Superoxide dismutase appears to be the main enzymatic defense against oxygen toxicity in B. stolpii. Induction of superoxide dismutase with 100% oxygen was manifested as an increase in the intensities of the two minor bands of activity, suggesting that isozyme I is constitutive, whereas isozymes II and III are inducible. The induction of isozymes II and III by 100% oxygen was prevented by an inhibitor of protein biosynthesis, chloramphenicol.

Diazoxide Modulates Cardiac Hypertrophy by Targeting H2O2 Generation and Mitochondrial Superoxide Dismutase Activity

2020 ◽  
Vol 13 (1) ◽  
pp. 76-83
Author(s):  
Aline Maria Brito Lucas ◽  
Joana Varlla de Lacerda Alexandre ◽  
Maria Thalyne Silva Araújo ◽  
Cicera Edna Barbosa David ◽  
Yuana Ivia Ponte Viana ◽  
...  
Keyword(s):  
Oxidative Stress ◽  
Superoxide Dismutase ◽  
Cardiac Hypertrophy ◽  
Superoxide Dismutase Activity ◽  
Heart Weight ◽  
Pharmacological Intervention ◽  
Wall Thickening ◽  
H2o2 Production ◽  
Mitochondrial Superoxide ◽  
Mitochondrial Superoxide Dismutase

Background: Cardiac hypertrophy involves marked wall thickening or chamber enlargement. If sustained, this condition will lead to dysfunctional mitochondria and oxidative stress. Mitochondria have ATP-sensitive K+ channels (mitoKATP) in the inner membrane that modulate the redox status of the cell. Objective: We investigated the in vivo effects of mitoKATP opening on oxidative stress in isoproterenol- induced cardiac hypertrophy. Methods: Cardiac hypertrophy was induced in Swiss mice treated intraperitoneally with isoproterenol (ISO - 30 mg/kg/day) for 8 days. From day 4, diazoxide (DZX - 5 mg/kg/day) was used in order to open mitoKATP (a clinically relevant therapy scheme) and 5-hydroxydecanoate (5HD - 5 mg/kg/day) or glibenclamide (GLI - 3 mg/kg/day) were used as mitoKATP blockers. Results: Isoproterenol-treated mice had elevated heart weight/tibia length ratios (HW/TL). Additionally, hypertrophic hearts had elevated levels of carbonylated proteins and Thiobarbituric Acid Reactive Substances (TBARS), markers of protein and lipid oxidation. In contrast, mitoKATP opening with DZX avoided ISO effects on gross hypertrophic markers (HW/TL), carbonylated proteins and TBARS, in a manner reversed by 5HD and GLI. Moreover, DZX improved mitochondrial superoxide dismutase activity. This effect was also blocked by 5HD and GLI. Additionally, ex vivo treatment of isoproterenol- induced hypertrophic cardiac tissue with DZX decreased H2O2 production in a manner sensitive to 5HD, indicating that this drug also acutely avoids oxidative stress. Conclusion: Our results suggest that diazoxide blocks oxidative stress and reverses cardiac hypertrophy. This pharmacological intervention could be a potential therapeutic strategy to prevent oxidative stress associated with cardiac hypertrophy.

scholarly journals Two New Compounds From the Heartwood of Dalbergia melanoxylon and Their Protective Effect on Hypoxia/Reoxygenation Injury in H9c2

2021 ◽  
Vol 16 (1) ◽  
pp. 1934578X2098777
Author(s):  
Yang Liu ◽  
Ni Zhang ◽  
Jun-wei He ◽  
Lan-ying Chen ◽  
Li Yang ◽  
...  
Keyword(s):  
Superoxide Dismutase ◽  
Lactate Dehydrogenase ◽  
Protective Effect ◽  
Superoxide Dismutase Activity ◽  
Spectral Evidence ◽  
Reoxygenation Injury ◽  
Dalbergia Melanoxylon ◽  
New Compounds ◽  
Hypoxia Reoxygenation

A new neoflavonoid, named as (7 R)-(-)-3′,5-dihydroxy-4′,2,4-trimethoxy-dalbergiquinol (1) and a new phenanthrenedione, named as 3′,7-dihydroxy-3,6- dimethoxy-9-phenyl-1,4-phenanthrenedione (2), together with 4 known compounds, 5- O-methyldalbergiphenol (3), 3′,7-dihydroxy-4′,3,6-trimethoxy-9-phenyl-1,4-phenanthrenedione (4), (+)-obtusafuran (5), and melanoxin (6) were isolated from the heartwood of Dalbergia melanoxylon. Their structures were elucidated on the basis of chemical and spectral evidence, as well as by comparison with literature data. Moreover, compound 1 showed a protective effect on hypoxia/reoxygenation injury in H9c2 at 10.0 μM by decreasing lactate dehydrogenase and malondialdehyde activity and enhancing superoxide dismutase activity.

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