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Pseudomonas putida
Published in Martin Koller, The Handbook of Polyhydroxyalkanoates, 2020
Maria Tsampika Manoli, Natalia Tarazona, Aranzazu Mato, Beatriz Maestro, Jesús M. Sanz, Juan Nogales, M. Auxiliadora Prieto
The second step of fatty acid degradation in P. putida KT2440 is realized by acyl-CoA dehydrogenases, FadE. They belong to a large family of flavoproteins and show activity towards a broad range of substrates. Depending on the substrate specificity of FadE, the enzyme can be classified into short, medium, long, or very long-chain acyl-CoA dehydrogenases. However, the boundary of classification is not tight as substrate specificities of particular enzymes may overlap [64]. The reaction of the dehydrogenation presents the rate-limiting step in the β-oxidation since FadE has the lowest activity among all β-oxidation enzymes in E. coli [65]. Initial work on P. putida KT2440 identified PP_2216 as a specific acyl-CoA dehydrogenase for short-chain aliphatic fatty acyl-CoAs [66] and the PP_0368 as an inducible phenylacyl-CoA dehydrogenase [67]. Recently, in silico analysis of its genome sequence revealed 21 putative acyl-CoA dehydrogenases (ACADs), four (PP_1893, PP_2039, PP_2048, and PP_2437) of which were functionally characterized by mutagenesis studies. The PP_1893 (FadE) and PP_2437 (FadE2) were proposed to directly participate in fatty acid degradation, while the 19 remaining putative ACADs have a redundant role or overlap in terms of function when P. putida KT2440 is grown on aliphatic fatty acids [68].
Biological System as Reactor for the Production of Biodegradable Thermoplastics, Polyhydroxyalkanoates
Published in Devarajan Thangadurai, Jeyabalan Sangeetha, Industrial Biotechnology, 2017
Akhilesh Kumar Singh, Nirupama Mallick
The PHA biosynthesis in Pseudomonas oleovorans and in many Pseudomonads including Pseudomonas aeruginosa belonging to the rRNA homology group I involves the biosynthetic route that includes the cyclic β- oxidation along with thiolytic cleavage of fatty acids, for example, 3-hydroxyacyl-CoA and intermediates of the β-oxidation pathways (Doi, 1990; Punrattanasin, 2001; Singh and Mallick, 2009a; Singh et al., 2013). These microorganisms synthesize MCL-PHAs and rarely LCL-PHAs from alkanes, alkanoates or alcohols. Contrary to Cupriavidus necator, these organisms normally do not synthesize PHAs comprising SCL monomers (SCL-PHAs). The β-oxidation of fatty acids could supply the foremost substrate flux for PHA polymerase (Lageveen et al., 1988). This cycle follows an enzymatic cascade of reactions where fatty acids are incorporated into the cell (Figure 11.4): they are activated to CoA thioesters, reduced to 2-trans- enoyl-CoA, and catalyzed by acyl-CoA dehydrogenase with FAD as a cofactor. These intermediates are transformed to S- (+)-3-hydroxyacyl-CoA and catalyzed by enoyl-CoA hydratase. The compound so generated is oxidized to 3-ketoacyl-CoA with the assistance of NAD dependent 3-ketoacyl-CoA dehydrogenase. Lastly, acetyl-CoA is cleaved from 3-ketoacyl-CoA and two carbons lesser fatty acid is synthesized. By reduction of 3-ketoacyl-CoA, a reaction catalyzed by a ketoacyl-CoA reductase, intermediate R-(–)-3-hydroxyacyl-CoA is produced. As the PHA synthase accepts merely the R-(–)-3-hydroxyacyl-CoA and the bacterial β-oxidation of fatty acids produces merely the S- (+)-3-hydroxyacyl-CoA, bacteria must have enzymes proficient of generating R-(–)-3-hydroxyacyl-CoA. One such enzyme is a 3-hydroxyacyl-CoA epimerase, mediating the reversible conversion of the S and R isomers of 3-hydroxyacyl-CoA. Thus, S- (+)-3-hydroxyacyl-CoA epimerizes to R-(–)-3-hydroxyacyl-CoA through 3-hydroxyacyl-CoA epimerase and the enoyl-CoA is converted to R-(–)-3-hydroxyacyl-CoA by enoyl-CoA hydratase activity. These are finally utilized by the PHA polymerase for the production of either MCL-PHAs or LCL-PHAs (Lageveen et al., 1988; Kraak et al., 1997; Singh and Mallick, 2009a).
Metabolomics profiling of valproic acid-induced symptoms resembling autism spectrum disorders using 1H NMR spectral analysis in rat model
Published in Journal of Toxicology and Environmental Health, Part A, 2022
Hyang Yeon Kim, Yong-Jae Lee, Sun Jae Kim, Jung Dae Lee, Suhkmann Kim, Mee Jung Ko, Ji-Woon Kim, Chan Young Shin, Kyu-Bong Kim
3-Hydroxyisovalerate and pimelate belong to a class of organic acids and short-chain fatty acids. There is a case study of a child with autism that showed long-chain acyl-CoA dehydrogenase deficiency (Clark-Taylor and Clark-Taylor 2004). Fatty acid β-oxidation is the major pathway to produce ATP and reducing power from different chain lengths of fatty acids, which are activated in the mitochondria and peroxisomes. The first reaction of mitochondrial fatty acid β-oxidation (FAO) in the mitochondria is catalyzed by acyl‐CoA dehydrogenase. With long-chain acyl-CoA dehydrogenase deficiency, the VPA-induced group might contain decreased levels of short-chain fatty acids in urine. In addition, when mitochondrial dysfunction occurs, β-oxidation of polyunsaturated fatty acids is diverted to the peroxisome, leading to generation of FADH2 by β-oxidation and production of hydrogen peroxide (H2O2) rather than energy in the peroxisome. Hydrogen peroxide induces oxidative stress in cells, and evidence suggested a relationship between oxidative stress and autism (Chauhan and Chauhan 2006; Rossignol and Frye 2014). Therefore, data suggested that urinary metabolites such as galactose, galactonate, 3-hydroxyisovalerate, valerate and pimelate might serve as significant biomarkers of VPA-induced effects resembling ASD.