scholarly journals Microbial metabolism of the pyridine ring. Metabolic pathways of pyridine biodegradation by soil bacteria

1975 ◽  
Vol 146 (1) ◽  
pp. 157-172 ◽  
Author(s):  
G K Watson ◽  
R B Cain
Keyword(s):  
Metabolic Pathways ◽  
Carbonyl Compounds ◽  
Soil Bacteria ◽  
Pyridine Ring ◽  
Formate Dehydrogenase ◽  
Isocitrate Lyase ◽  
Rapid Loss ◽  
Semialdehyde Dehydrogenase ◽  
Nocardia Sp ◽  
Succinate Semialdehyde

1. Two bacteria, a Bacillus sp. and a Nocardia sp. (strain Z1) were isolated from soil by enrichment with 0.1 percent (v/v) pyridine and grew rapidly on this compound as sole C, N and energy source. The monohydroxypyridines, tetrahydropyridine, piperidine and some other analogues were not utilized for growth or oxidized by washed suspensions of either bacterium. 2. Cell-free extracts were unable to metabolize pyridine even after supplementation with a variety of cofactors or protecting agents. Treatment of cells with toluene led to rapid loss of the ability to oxidize pyridine. 3. In the presence of 10mM-semicarbazide at pH 6.0, Nocardia Z1 accumulated a semialdehyde idenditied as its 2,4-dinitrophenylhydrazone by chromatography, mixed melting point, mass spectrometry and isotope trapping from [2,6(-14)C]pyridine as glutarate semialdehyde. 4. Extracts of this bacterium prepared from cells grown with pyridine or exposed to the gratuitous inducer 2-picoline, contained high activities of a specific glutarate semialdehyde dehydrogenase. 5. Cells grown with pyridine or glutarate also contained a glutaric dialdehyde dehydrogenase, an acyl-CoA synthetase and elevated amounts of isocitrate lyase but no glutaryl-CoA dehydrogenase. 6. Bacillus 4 accumulated in the presence of 10mM-semicarbazide several acidic carbonyl compounds from pyridine among which was succinate semialdehyde. Extracts of this bacillus after growth of the cells with pyridine contained an inducible succinate semialdehyde dehydrogenase in amounts at least 50-fold over those found in succinate-grown cells. 7. Two mutants of this bacillus, selected for their inability to grow on pyridine were deficient in succinate semialdehyde dehydrogenase. 8. In the presence of 0.2mM-KCN, washed suspensions of Bacillus 4 accumulated formate and possibly formamide from pyridine. The use of [14C]pyridine showed that formate was derived from C-2 of the pyridine ring. 9. The organism had a specific formamide amidohydrolase cleaving formamide quantitatively to formate and NH3. 10. Formate was further oxidized by the particle fraction. There was no soluble formate dehydrogenase in extracts.

scholarly journals Metabolic Pathways for Cytotoxic End Product Formation from Glutamate- and Aspartate-Containing Peptides byPorphyromonas gingivalis

2000 ◽  
Vol 182 (17) ◽  
pp. 4704-4710 ◽  
Author(s):  
Nobuhiro Takahashi ◽  
Takuichi Sato ◽  
Tadashi Yamada
Keyword(s):  
Metabolic Pathways ◽  
Product Formation ◽  
Acetyl Coa ◽  
Sequential Reaction ◽  
Semialdehyde Dehydrogenase ◽  
Cell Extracts ◽  
Coa Transferase ◽  
End Products ◽  
Succinate Semialdehyde ◽  
Pyruvate Oxidoreductase

ABSTRACT Metabolic pathways involved in the formation of cytotoxic end products by Porphyromonas gingivalis were studied. The washed cells of P. gingivalis ATCC 33277 utilized peptides but not single amino acids. Since glutamate and aspartate moieties in the peptides were consumed most intensively, a dipeptide of glutamate or aspartate was then tested as a metabolic substrate of P. gingivalis. P. gingivalis cells metabolized glutamylglutamate to butyrate, propionate, acetate, and ammonia, and they metabolized aspartylaspartate to butyrate, succinate, acetate, and ammonia. Based on the detection of metabolic enzymes in the cell extracts and stoichiometric calculations (carbon recovery and oxidation/reduction ratio) during dipeptide degradation, the following metabolic pathways were proposed. Incorporated glutamylglutamate and aspartylaspartate are hydrolyzed to glutamate and aspartate, respectively, by dipeptidase. Glutamate is deaminated and oxidized to succinyl-coenzyme A (CoA) by glutamate dehydrogenase and 2-oxoglutarate oxidoreductase. Aspartate is deaminated into fumarate by aspartate ammonia-lyase and then reduced to succinyl-CoA by fumarate reductase and acyl-CoA:acetate CoA-transferase or oxidized to acetyl-CoA by a sequential reaction of fumarase, malate dehydrogenase, oxaloacetate decarboxylase, and pyruvate oxidoreductase. The succinyl-CoA is reduced to butyryl-CoA by a series of enzymes, including succinate-semialdehyde dehydrogenase, 4-hydroxybutyrate dehydrogenase, and butyryl-CoA oxidoreductase. A part of succinyl-CoA could be converted to propionyl-CoA through the reactions initiated by methylmalonyl-CoA mutase. The butyryl- and propionyl-CoAs thus formed could then be converted into acetyl-CoA by acyl-CoA:acetate CoA-transferase with the formation of corresponding cytotoxic end products, butyrate and propionate. The formed acetyl-CoA could then be metabolized further to acetate.

scholarly journals SSADH Variants Increase Susceptibility of U87 Cells to Mitochondrial Pro-Oxidant Insult

2020 ◽  
Vol 21 (12) ◽  
pp. 4374
Author(s):  
Giovanna Menduti ◽  
Alessandra Vitaliti ◽  
Concetta Rosa Capo ◽  
Daniele Lettieri-Barbato ◽  
Katia Aquilano ◽  
...  
Keyword(s):  
Lipid Peroxidation ◽  
Mitochondrial Function ◽  
Antioxidant Defense ◽  
Mitochondrial Morphology ◽  
Common Snps ◽  
Protein Markers ◽  
Triple Mutant ◽  
Transfected Cells ◽  
Semialdehyde Dehydrogenase ◽  
Succinate Semialdehyde

Succinate semialdehyde dehydrogenase (SSADH) is a mitochondrial enzyme, encoded by ALDH5A1, mainly involved in γ-aminobutyric acid (GABA) catabolism and energy supply of neuronal cells, possibly contributing to antioxidant defense. This study aimed to further investigate the antioxidant role of SSADH, and to verify if common SNPs of ALDH5A1 may affect SSADH activity, stability, and mitochondrial function. In this study, we used U87 glioblastoma cells as they represent a glial cell line. These cells were transiently transfected with a cDNA construct simultaneously harboring three SNPs encoding for a triple mutant (TM) SSADH protein (p.G36R/p.H180Y/p.P182L) or with wild type (WT) cDNA. SSADH activity and protein level were measured. Cell viability, lipid peroxidation, mitochondrial morphology, membrane potential (ΔΨ), and protein markers of mitochondrial stress were evaluated upon Paraquat treatment, in TM and WT transfected cells. TM transfected cells show lower SSADH protein content and activity, fragmented mitochondria, higher levels of peroxidized lipids, and altered ΔΨ than WT transfected cells. Upon Paraquat treatment, TM cells show higher cell death, lipid peroxidation, 4-HNE protein adducts, and lower ΔΨ, than WT transfected cells. These results reinforce the hypothesis that SSADH contributes to cellular antioxidant defense; furthermore, common SNPs may produce unstable, less active SSADH, which could per se negatively affect mitochondrial function and, under oxidative stress conditions, fail to protect mitochondria.

γ-Aminobutyrate transaminase limits the catabolism of γ-aminobutyrate in cold-stressed Arabidopsis plants: insights from an overexpression mutant

Botany ◽  
2010 ◽  
Vol 88 (5) ◽  
pp. 522-527 ◽  
Author(s):  
Jeffrey P. Simpson ◽  
Shawn M. Clark ◽  
Andrea Portt ◽  
Wendy L. Allan ◽  
Amina Makhmoudova ◽  
...  
Keyword(s):  
Krebs Cycle ◽  
Wild Type ◽  
Chain Reaction ◽  
Leaf Extracts ◽  
Semialdehyde Dehydrogenase ◽  
Succinate Semialdehyde ◽  
Transgenic Lines ◽  
Constitutive Overexpression ◽  
Polymerase Chain ◽  
Selection Of

We tested the hypothesis that γ-aminobutyrate transaminase (GABA-T) regulates the supply of succinate semialdehyde for succinate semialdehyde dehydrogenase or NADPH-dependent glyoxylate/succinate semialdehyde reductase 1 (GLYR1) during stress. Constitutive overexpression (OX) lines of GABA-T were generated in Arabidopsis via the floral-dip method for Agrobacterium-mediated transformation. Polymerase chain reaction enabled selection of four transgenic lines with higher GABA-T transcript levels than the wild-type (WT), but assay of cell-free leaf extracts revealed that only OX1 had elevated GABA-T activity. Brief cold treatments (4 °C exposure for 20 min or 1 h in the dark) increased leaf GABA concentrations in both the WT and OX1, but the concentrations in OX1 were consistently lower. These findings confirm that GABA-T limits the catabolism of GABA when its production is stimulated by stress, and suggest a bioengineering strategy for improving the availability of succinate semialdehyde for the Krebs cycle or GLYR1, a potential redox-modulating reaction during stress.

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