scholarly journals Identification of the Polyhydroxyalkanoate (PHA)-Specific Acetoacetyl Coenzyme A Reductase among Multiple FabG Paralogs in Haloarcula hispanica and Reconstruction of the PHA Biosynthetic Pathway in Haloferax volcanii

2009 ◽  
Vol 75 (19) ◽  
pp. 6168-6175 ◽  
Author(s):  
Jing Han ◽  
Qiuhe Lu ◽  
Ligang Zhou ◽  
Hailong Liu ◽  
Hua Xiang
Keyword(s):  
Biosynthetic Pathway ◽  
Coenzyme A ◽  
Reductase Activity ◽  
Halophilic Archaea ◽  
Haloferax Volcanii ◽  
Pha Synthase ◽  
Haloarcula Marismortui ◽  
Coa Reductase ◽  
Haloarcula Hispanica ◽  
Acetoacetyl Coa Reductase

ABSTRACT Genome-wide analysis has revealed abundant FabG (β-ketoacyl-ACP reductase) paralogs, with uncharacterized biological functions, in several halophilic archaea. In this study, we identified for the first time that the fabG1 gene, but not the other five fabG paralogs, encodes the polyhydroxyalkanoate (PHA)-specific acetoacetyl coenzyme A (acetoacetyl-CoA) reductase in Haloarcula hispanica. Although all of the paralogous fabG genes were actively transcribed, only disruption or knockout of fabG1 abolished PHA synthesis, and complementation of the ΔfabG1 mutant with the fabG1 gene restored both PHA synthesis capability and the NADPH-dependent acetoacetyl-CoA reductase activity. In addition, heterologous coexpression of the PHA synthase genes (phaEC) together with fabG1, but not its five paralogs, reconstructed the PHA biosynthetic pathway in Haloferax volcanii, a PHA-defective haloarchaeon. Taken together, our results indicate that FabG1 in H. hispanica, and possibly its counterpart in Haloarcula marismortui, has evolved the distinct function of supplying precursors for PHA biosynthesis, like PhaB in bacteria. Hence, we suggest the renaming of FabG1 in both genomes as PhaB, the PHA-specific acetoacetyl-CoA reductase of halophilic archaea.

scholarly journals INHIBITION OF 3-HYDROXY-3-METHYLGLUTARYL-COENZYME A REDUCTASE ACTIVITY BY EXTRACTS OF GARCINIA XANTHOCHYMUS MESOCARP AND TOTAL FLAVONOID ASSAY QUANTIFICATION OF THE MOST ACTIVE EXTRACT

2018 ◽  
Vol 10 (1) ◽  
pp. 264
Author(s):  
Megawati . ◽  
Berna Elya ◽  
Nuraini Puspitasari
Keyword(s):  
Ethyl Acetate ◽  
Coenzyme A ◽  
Ethyl Acetate Extract ◽  
Reductase Activity ◽  
Total Flavonoid ◽  
Phytochemical Screening ◽  
Methanol Extracts ◽  
Garcinia Xanthochymus ◽  
Inhibitory Activities ◽  
Coa Reductase

Objective: This study aims to determine the inhibitory activity of Garcinia xanthochymus mesocarp extracts against 3-hydroxy-3-methylglutaryl-coenzyme A (HMG-CoA) reductase.Methods: G. xanthochymus mesocarp was macerated sequentially using n-hexane, ethyl acetate, and methanol. Phytochemical screening andquantification of total flavonoids were performed on the most active extract.Results: Based on the tests, n-hexane, ethyl acetate, and methanol extracts had inhibitory activities of 12.30±1.098%, 55.63±10.584%, and44.01±1.053%, respectively. The results showed that the ethyl acetate is the most active extract, containing flavonoid, terpenoid, glycoside, andanthraquinone compounds. The amount of total flavonoid contained in ethyl acetate extract was 1.61% or 16.114 mg QE/g toward quercetin.Conclusion: The n-hexane, ethyl acetate, and methanol extracts of G. xanthochymus have inhibitory actions against HMG-CoA reductase activityin vitro. Further research is still needed to strengthen this finding.

scholarly journals Acetoacetyl Coenzyme A Reductase and Polyhydroxybutyrate Synthesis in Rhizobium(Cicer) sp. Strain CC 1192

1998 ◽  
Vol 64 (8) ◽  
pp. 2859-2863 ◽  
Author(s):  
Shahid N. Chohan ◽  
Les Copeland
Keyword(s):  
Coenzyme A ◽  
Citrate Synthase ◽  
Living Cells ◽  
High Ratio ◽  
Free Living ◽  
Insoluble Material ◽  
Living State ◽  
Biochemical Level ◽  
Coa Reductase ◽  
Acetoacetyl Coa Reductase

ABSTRACT Biochemical controls that regulate the biosynthesis of poly-3-hydroxybutyrate (PHB) were investigated in Rhizobium(Cicer) sp. strain CC 1192. This species is of interest for studying PHB synthesis because the polymer accumulates to a large extent in free-living cells but not in bacteroids during nitrogen-fixing symbiosis with chickpea (Cicer arietinumL.) plants. Evidence is presented that indicates that CC 1192 cells retain the enzymic capacity to synthesize PHB when they differentiate from the free-living state to the bacteroid state. This evidence includes the incorporation by CC 1192 bacteroids of radiolabel from [14C]malate into 3-hydroxybutyrate which was derived by chemically degrading insoluble material from bacteroid pellets. Furthermore, the presence of an NADPH-dependent acetoacetyl coenzyme A (CoA) reductase, which was specific forR-(−)-3-hydroxybutyryl-CoA and NADP+ in the oxidative direction, was demonstrated in extracts from free-living and bacteroid cells of CC 1192. Activity of this enzyme in the reductive direction appeared to be regulated at the biochemical level mainly by the availability of substrates. The CC 1192 cells also contained an NADH-specific acetoacetyl-CoA reductase which oxidizedS-(+)-3-hydroxybutyryl-CoA. A membrane preparation from CC 1192 bacteroids readily oxidized NADH but not NADPH, which is suggested to be a major source of reductant for nitrogenase. Thus, a high ratio of NADPH to NADP+, which could enhance delivery of reductant to nitrogenase, could also favor the reduction of acetoacetyl-CoA for PHB synthesis. This would mean that fine controls that regulate the partitioning of acetyl-CoA between citrate synthase and 3-ketothiolase are important in determining whether PHB accumulates.

scholarly journals A new method for assaying rat liver microsomal 3-hydroxy-3-methylglutaryl-coenzyme A reductase activity and its application in a study of the effect of dietary cholesterol on this effect of dietary cholesterol on this enzyme

1977 ◽  
Vol 164 (3) ◽  
pp. 501-508 ◽  
Author(s):  
Y A Baqir ◽  
R Booth
Keyword(s):  
Rat Liver ◽  
Cholesterol Ester ◽  
Time Course ◽  
Coenzyme A ◽  
Reductase Activity ◽  
Dietary Cholesterol ◽  
New Method ◽  
Coa Reductase ◽  
Microsomal Cholesterol ◽  
Coenzyme A Reductase

A new method suitable for measuring rat liver 3-hydroxy-3-methylglutaryl-CoA reductase activity is described and its advantages over methods previously available are discussed. An accurate time course was measured for the inhibition of liver microsomal 3-hydroxy-3-methylglutaryl-CoA reductase activity by dietary cholesterol; this enzyme was affected 1 1/4 h after the rats began to consume a cholesterol-rich diet. In this experiment there was no correlation between concentrations of microsomal cholesterol ester and the activity of 3-hydroxy-3-methylglutary-CoA reductase.

scholarly journals Malonyl-Coenzyme A Reductase in the Modified 3-Hydroxypropionate Cycle for Autotrophic Carbon Fixation in Archaeal Metallosphaera and Sulfolobus spp.

2006 ◽  
Vol 188 (24) ◽  
pp. 8551-8559 ◽  
Author(s):  
Birgit Alber ◽  
Marc Olinger ◽  
Annika Rieder ◽  
Daniel Kockelkorn ◽  
Björn Jobst ◽  
...  
Keyword(s):  
Amino Acid ◽  
Carbon Fixation ◽  
Coenzyme A ◽  
Reductase Activity ◽  
Growth Conditions ◽  
Significant Similarity ◽  
Semialdehyde Dehydrogenase ◽  
Malonyl Coa ◽  
Taxonomic Groups ◽  
Coa Reductase

ABSTRACT Autotrophic members of the Sulfolobales (Crenarchaeota) contain acetyl-coenzyme A (CoA)/propionyl-CoA carboxylase as the CO2 fixation enzyme and use a modified 3-hydroxypropionate cycle to assimilate CO2 into cell material. In this central metabolic pathway malonyl-CoA, the product of acetyl-CoA carboxylation, is further reduced to 3-hydroxypropionate. Extracts of Metallosphaera sedula contained NADPH-specific malonyl-CoA reductase activity that was 10-fold up-regulated under autotrophic growth conditions. Malonyl-CoA reductase was partially purified and studied. Based on N-terminal amino acid sequencing the corresponding gene was identified in the genome of the closely related crenarchaeum Sulfolobus tokodaii. The Sulfolobus gene was cloned and heterologously expressed in Escherichia coli, and the recombinant protein was purified and studied. The enzyme catalyzes the following reaction: malonyl-CoA + NADPH + H+ → malonate-semialdehyde + CoA + NADP+. In its native state it is associated with small RNA. Its activity was stimulated by Mg2+ and thiols and inactivated by thiol-blocking agents, suggesting the existence of a cysteine adduct in the course of the catalytic cycle. The enzyme was specific for NADPH (Km = 25 μM) and malonyl-CoA (Km = 40 μM). Malonyl-CoA reductase has 38% amino acid sequence identity to aspartate-semialdehyde dehydrogenase, suggesting a common ancestor for both proteins. It does not exhibit any significant similarity with malonyl-CoA reductase from Chloroflexus aurantiacus. This shows that the autotrophic pathway in Chloroflexus and Sulfolobaceae has evolved convergently and that these taxonomic groups have recruited different genes to bring about similar metabolic processes.

scholarly journals Inhibition of hydroxymethylglutaryl coenzyme A reductase activity induces a paradoxical increase in DNA synthesis in myeloid leukemia cells

Blood ◽  
1991 ◽  
Vol 77 (5) ◽  
pp. 1064-1070 ◽  
Author(s):  
RJ Hohl ◽  
RA Larson ◽  
V Mannickarottu ◽  
S Yachnin
Keyword(s):  
Dna Synthesis ◽  
Myeloid Leukemia ◽  
Coenzyme A ◽  
Reductase Activity ◽  
Myelogenous Leukemia ◽  
Leukemia Cells ◽  
Hmg Coa Reductase ◽  
Cellular Dna ◽  
Coa Reductase ◽  
Inhibition Of Dna Synthesis

Abstract The effects of competitive inhibition of hydroxymethylglutaryl coenzyme A (HMG CoA) reductase by compactin on the in vitro proliferation of peripheral blood myeloid leukemia cells were studied using the cells from 45 patients with acute myeloid leukemia or chronic myelogenous leukemia in blast phase. The cells from 58% of these patients showed a dose-related inhibition of DNA synthesis when incubated with compactin. Unexpectedly, cells from 18% of the patients were resistant to the inhibitory effects of compactin on DNA synthesis and responded to the HMG CoA reductase inhibition with an actual increase in the incorporation of 14C-labeled thymidine into DNA. Another 18% of the patients studied displayed both inhibition and stimulation of DNA synthesis in a biphasic response depending on the particular concentration of compactin used. The maximum enhanced rates of cellular DNA synthesis were observed with lower compactin concentrations (5 x 10(-7) mol/L) than were required for maximum inhibition of DNA synthesis (10(-5) mol/L). Leukemia cells displaying a stimulated response to compactin had a significantly lower baseline DNA synthetic rate than did cells that showed an inhibitory response of DNA synthesis to compactin. There was no correlation between these cells' varying DNA synthetic response to compactin and measures of baseline HMG CoA reductase activity or acetate conversion to cholesterol. Whereas the observation of cellular DNA synthesis stimulation by HMG CoA reductase inhibition has not been observed in other mammalian cells and seems paradoxical, explanations may emerge in light of our growing knowledge concerning the importance of isoprenylation for the function of certain cell regulatory proteins.

scholarly journals Activity of 3-hydroxy-3-methylglutaryl-coenzyme A reductase in brains of adult and 7-day-old rats

1976 ◽  
Vol 154 (2) ◽  
pp. 559-560 ◽  
Author(s):  
M M. Sudjic ◽  
R Booth
Keyword(s):  
Rat Brain ◽  
Coenzyme A ◽  
Reductase Activity ◽  
Cholesterol Biosynthesis ◽  
Adult Brain ◽  
Adult Rat ◽  
Adult Rat Brain ◽  
Old Rats ◽  
Coa Reductase ◽  
Coenzyme A Reductase

Rat brain contains 3-hydroxy-3-methylglutaryl-CoA reductase activity, but this enzyme is far more active in 7-day-old brain than in adult brain. This difference may partly explain why cholesterol biosynthesis is more rapid in growing than in adult rat brain.

scholarly journals Molecular Characterization of the phaECHm Genes, Required for Biosynthesis of Poly(3-Hydroxybutyrate) in the Extremely Halophilic Archaeon Haloarcula marismortui

2007 ◽  
Vol 73 (19) ◽  
pp. 6058-6065 ◽  
Author(s):  
Jing Han ◽  
Qiuhe Lu ◽  
Ligang Zhou ◽  
Jian Zhou ◽  
Hua Xiang
Keyword(s):  
Minimal Medium ◽  
Transcriptional Start Site ◽  
Dry Weight ◽  
Complete Loss ◽  
Pha Synthase ◽  
Class Iii ◽  
Haloarcula Marismortui ◽  
Extremely Halophilic Archaeon ◽  
Haloarcula Hispanica

ABSTRACT Although many haloarchaea produce biodegradable polyhydroxyalkanoates (PHAs), the genes involved in PHA synthesis in the domain of Archaea have not yet been experimentally investigated yet. In this study, we revealed that Haloarcula marismortui was able to accumulate poly(3-hydroxybutyrate) (PHB) up to 21% of cellular dry weight when cultured in a minimal medium with excessive glucose and identified the phaE Hm and phaC Hm genes, probably encoding two subunits of a class III PHA synthase. These two genes were adjacent and directed by a single promoter located 26 bp upstream of the transcriptional start site and were constitutively expressed under both nutrient-rich and -limited conditions. Interestingly, PhaCHm was revealed to be strongly bound with the PHB granules, but PhaEHm seemed not to be. Introduction of either the phaE Hm or phaC Hm gene into Haloarcula hispanica, which harbors highly homologous phaEC Hh genes, could enhance the PHB synthesis in the recombinant strains, while coexpression of the both genes always generated the highest PHB yield. Significantly, knockout of the phaEC Hh genes in H. hispanica led to a complete loss of the PHA synthase activity. Complementation with phaEC Hm genes, but not a single one, restored the capability of PHB accumulation as well as the PHA synthase activity in this phaEC-deleted haloarchaeon. These results indicated that the phaEC genes are required for biosynthesis of PHB and might encode an active PHA synthase in the Haloarcula species.

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