Role Of Oxidoreductases Research Articles

Studies on estrone biodegradation potential of cyanobacterial species

Abstract The estrone (E1) excreted through faeces and urine by livestock and humans are present in the water bodies. Even at very low concentrations (0.1–1 ng/l) it poses threat to living organisms as it can bioaccumulate through the food chain. It binds to and activate the estrogen receptors and mimics a normal endocrine response which changes the homeostasis of animals and humans and potentially impairs the reproductive ability. It is a major pollutant and is also designated as an endocrine disrupting compound by the World Health Organization. Hence, there is an urgent need to find out ways for their bioremediation. In the present study, 16 different aquatic cyanobacteria species were screened for estrone bioremediation and the experiments were done in three phases. The first two phases included determination of estrone toxicity and its bioremediation in/by cyanobacteria and the third phase included the determination of degradative role of laccase enzyme. Concentration dependent toxic effect of estrone was observed at 50, 100, and 200 ppm estrone but at 20 ppm estrone slight growth promotion was observed. The degradation efficiency ranged between 53.7% and 94.5%. It was highest at 20 ppm estrone in Spirulina CPCC-695. In order to find out the role of oxidoreductases in estrone (phenolics) degradation, laccase activity was monitored. Maximum laccase activity (34.22 UL−1) was found in Spirulina CPCC-695. Therefore, use of cyanobacteria especially Spirulina CPCC-695 could be recommended for degradation of estrone in aquatic bodies.

Redox diversity in ERAD-mediated protein retrotranslocation from the endoplasmic reticulum: a complex puzzle.

Misfolded and incorrectly assembled proteins in the secretory pathway are eliminated by ubiquitylation and proteasomal degradation in a process known as ER-associated degradation (ERAD). Retrotranslocation of diverse substrates including misfolded proteins and viruses occurs through channels in the ER membrane, which are also utilized for host cell penetration by A/B class protein toxins such as cholera toxin, ricin or K28. According to the current view, disulfide-bonded proteins must either be reduced or rearranged to ensure translocation competence and entry into the cytosol from the ER. As the underlying mechanisms are still largely mysterious, we here focus on the redox status and disulfide isomerization of ERAD substrates and the role of oxidoreductases in the essential process of ER-to-cytosol retrotranslocation.

Correction: The Role of Oxidoreductases in Determining the Function of the Neisserial Lipid A Phosphoethanolamine Transferase Required for Resistance to Polymyxin

Correction: The Role of Oxidoreductases in Determining the Function of the Neisserial Lipid A Phosphoethanolamine Transferase Required for Resistance to Polymyxin

The role of oxidoreductases in determining the function of the neisserial lipid A phosphoethanolamine transferase required for resistance to polymyxin.

The decoration of the lipid A headgroups of the lipooligosaccharide (LOS) by the LOS phosphoethanolamine (PEA) transferase (LptA) in Neisseria spp. is central for resistance to polymyxin. The structure of the globular domain of LptA shows that the protein has five disulphide bonds, indicating that it is a potential substrate of the protein oxidation pathway in the bacterial periplasm. When neisserial LptA was expressed in Escherichia coli in the presence of the oxidoreductase, EcDsbA, polymyxin resistance increased 30-fold. LptA decorated one position of the E. coli lipid A headgroups with PEA. In the absence of the EcDsbA, LptA was degraded in E. coli. Neisseria spp. express three oxidoreductases, DsbA1, DsbA2 and DsbA3, each of which appear to donate disulphide bonds to different targets. Inactivation of each oxidoreductase in N. meningitidis enhanced sensitivity to polymyxin with combinatorial mutants displaying an additive increase in sensitivity to polymyxin, indicating that the oxidoreductases were required for multiple pathways leading to polymyxin resistance. Correlates were sought between polymyxin sensitivity, LptA stability or activity and the presence of each of the neisserial oxidoreductases. Only meningococcal mutants lacking DsbA3 had a measurable decrease in the amount of PEA decoration on lipid A headgroups implying that LptA stability was supported by the presence of DsbA3 but did not require DsbA1/2 even though these oxidoreductases could oxidise the protein. This is the first indication that DsbA3 acts as an oxidoreductase in vivo and that multiple oxidoreductases may be involved in oxidising the one target in N. meningitidis. In conclusion, LptA is stabilised by disulphide bonds within the protein. This effect was more pronounced when neisserial LptA was expressed in E. coli than in N. meningitidis and may reflect that other factors in the neisserial periplasm have a role in LptA stability.

Hydrogen peroxide production in wheat leaves infected with the fungus Septoria nodorum Berk. Strains with different virulence

The effect of two strains of the phytopathogenic fungus Septoria nodorum Berk. of different virulence on the intensity of local generation of hydrogen peroxide in common wheat leaves and the role of oxidoreductases in this process was studied. Differences in the pattern of hydrogen peroxide production in wheat plants infected with high- and low-virulence pathogen strains have been found. The low-virulent S. nodorum strain caused a long-term hydrogen peroxide (H2O2) generation in the infection zone, whereas the inoculation of leaves with the highly virulent strain resulted in a transient short-term increase in the H2O2 concentration at the initial moment of contact between the plant and the fungus. It was shown that the low level of H2O2 prOduction by plant cells at the initial stages of pathogenesis facilitates S. nodorum growth and development. The decrease in the H2O2 concentration induced by the highly virulent S. nodorum strain is determined by inhibition of the oxalate oxidase activity in plant tissues and by the ability of the fungus to actively synthesize an extracellular catalase. The pattern of hydrogen peroxide generation at the initial stages of septoriosis may serve as an index of virulence of S. nodorum population.

De-remodeling of Kv channels in failing rat heart: Role of oxidoreductases

De-remodeling of Kv channels in failing rat heart: Role of oxidoreductases

Reductive biotransformations of organic compounds by saccharomyces cerevisiae: Study of oxidoreductases involved using electrophoretic zymograms

The role of oxidoreductases in reduction of carbonyl compounds was investigated by application of zymogram techniques. Eight bands were observed using ethanol with nicotinamide adenine dinucleotide (NAD) as coenzyme. Bands observed with lactic acid and (R)-(-)-phenyl-1,2-ethanediol with nicotinamide adenine dinucleotide phosphate (NADP) had similar R(m) values. 2-Hydroxyvalerate and malate manifested bands having similar R(m) values and were active with both NAD and NADP. Based on their structural similarity and identical R(m) values, oxidation of 1,4-cyclooctanediol (band #2) and cis-1,5-cyclooctanediol may be due to a common enzyme. The PAGE-zymogram technique may be used on a preparative scale to facilitate purification and full characterization on the observed stained bands.