Effects of propionate and carnitine on the hepatic oxidation of short- and medium-chain-length fatty acids

Accumulation of propionate, or its metabolic product propionyl-CoA, can disrupt normal cellular metabolism. The present study examined the effects of propionate, or propionyl-CoA generated during the oxidation of odd-chain-length fatty acids, on hepatic oxidation of short- and medium-chain-length fatty acids. In isolated hepatocytes, ketone-body formation from odd-chain-length fatty acids was slow as compared with even-chain-length fatty acid substrates, and increased as the carbon chain length was increased from five to seven to nine. In contrast, rates of ketogenesis from butyrate, hexonoate and octanoate were all approximately equal. Propionate (10 mM) inhibited ketogenesis from butyrate, hexanoate and octanoate by 81%, 53% and 18% respectively. Addition of carnitine had no effect on ketogenesis from the even-chain-length fatty acids, but increased the rate of ketone-body formation from pentanoate (by 53%), heptanoate (by 28%) and from butyrate or hexanoate in the presence of propionate. The inhibitory effect of propionate could not be explained by shunting acetyl-CoA into the tricarboxylic acid cycle, as CO2 formation from butyrate was also decreased by propionate. Examination of the hepatocyte CoA pool during oxidation of butyrate demonstrated that addition of propionate decreased acetyl-CoA and CoA as propionyl-CoA accumulated. Addition of carnitine decreased propionyl-CoA by 50% (associated with production of propionylcarnitine) and increased acetyl-CoA and CoA. Similar changes in the CoA pool were seen during the oxidation of pentanoate. These results demonstrate that accumulation of propionyl-CoA results in inhibition of short-chain fatty acid oxidation. Carnitine can partially reverse this inhibition. Changes in the hepatocyte CoA pool are consistent with carnitine acting by generating propionylcarnitine, thereby decreasing propionyl-CoA and increasing availability of free CoA. The data provide further evidence of the potential cellular toxicity from organic acid accretion, and supports the concept that carnitine's interaction with the cellular CoA pool can have a beneficial effect on cellular metabolism and function under conditions of unusual organic acid accumulation.

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Effects of adrenaline on ketogenesis from long- and medium-chain fatty acids in starved rats

Biochemical Journal ◽

10.1042/bj2040749 ◽

1982 ◽

Vol 204 (3) ◽

pp. 749-756 ◽

Cited By ~ 13

Author(s):

M C Sugden ◽

D I Watts ◽

C E Marshall

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Blood Glucose ◽

Carboxylic Acid ◽

Chain Length ◽

Clinical Significance ◽

Ketone Body ◽

Medium Chain ◽

Medium Chain Fatty Acids ◽

Increase Blood Glucose

1. Injection of adrenaline into 24 h-starved rats caused a 69% decrease in blood [ketone-body] (3-hydroxybutyrate plus acetoacetate), accompanied by a decreased [3-hydroxybutyrate]/[acetoacetate] ratio. Blood [glucose] and [lactate] increased, but [alanine] was unchanged. 2. Adrenaline also decreased [ketone-body] after intragastric feeding of both long- and medium-chain triacylglycerol. The latter decrease was observed after suppression of lipolysis with 5-methylpyrazole-3-carboxylic acid, indicating that the antiketogenic action of adrenaline was not dependent on the chain length of the precursor fatty acid. 3. The actions of adrenaline to decrease blood [ketone-body] and to increase blood [glucose] were not observed after administration of 3-mercaptopicolinate, an inhibitor of gluconeogenesis. This suggests that these effects of the hormone are related. 4. The possible clinical significance of the results is discussed with reference to the restricted ketosis often observed after surgical or orthopaedic injury.

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Synthesis of medium chain length fatty acid ethyl esters in engineered Escherichia coli using endogenously produced medium chain fatty acids

Enzyme and Microbial Technology ◽

10.1016/j.enzmictec.2013.03.012 ◽

2013 ◽

Vol 53 (2) ◽

pp. 128-133 ◽

Cited By ~ 12

Author(s):

Liping Fan ◽

Junfeng Liu ◽

Kaili Nie ◽

Luo Liu ◽

Fang Wang ◽

...

Keyword(s):

Escherichia Coli ◽

Fatty Acids ◽

Fatty Acid ◽

Chain Length ◽

Fatty Acid Ethyl Esters ◽

Ethyl Esters ◽

Medium Chain ◽

Medium Chain Fatty Acids ◽

Medium Chain Length ◽

Engineered Escherichia Coli

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Production of fatty acids inRalstonia eutrophaH16 by engineeringβ-oxidation and carbon storage

PeerJ ◽

10.7717/peerj.1468 ◽

2015 ◽

Vol 3 ◽

pp. e1468 ◽

Cited By ~ 19

Author(s):

Janice S. Chen ◽

Brendan Colón ◽

Brendon Dusel ◽

Marika Ziesack ◽

Jeffrey C. Way ◽

...

Keyword(s):

Fatty Acids ◽

Fatty Acid ◽

Chain Length ◽

Acid Production ◽

Ralstonia Eutropha ◽

Fatty Acid Production ◽

Acid Yield ◽

Medium Chain ◽

Medium Chain Length ◽

Coa Ligase

Ralstonia eutrophaH16 is a facultatively autotrophic hydrogen-oxidizing bacterium capable of producing polyhydroxybutyrate (PHB)-based bioplastics. As PHB’s physical properties may be improved by incorporation of medium-chain-length fatty acids (MCFAs), and MCFAs are valuable on their own as fuel and chemical intermediates, we engineeredR. eutrophafor MCFA production. Expression ofUcFatB2, a medium-chain-length-specific acyl-ACP thioesterase, resulted in production of 14 mg/L laurate in wild-typeR. eutropha. Total fatty acid production (22 mg/L) could be increased up to 2.5-fold by knocking out PHB synthesis, a major sink for acetyl-CoA, or by knocking out the acyl-CoA ligasefadD3, an entry point for fatty acids intoβ-oxidation. As ΔfadD3mutants still consumed laurate, and because theR. eutrophagenome is predicted to encode over 50 acyl-CoA ligases, we employed RNA-Seq to identify acyl-CoA ligases upregulated during growth on laurate. Knockouts of the three most highly upregulated acyl-CoA ligases increased fatty acid yield significantly, with one strain (ΔA2794) producing up to 62 mg/L free fatty acid. This study demonstrates that homologousβ-oxidation systems can be rationally engineered to enhance fatty acid production, a strategy that may be employed to increase yield for a range of fuels, chemicals, and PHB derivatives inR. eutropha.

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The Thermal and Mechanical Properties of Medium Chain-Length Polyhydroxyalkanoates Produced by Pseudomonas putida LS46 on Various Substrates

Frontiers in Bioengineering and Biotechnology ◽

10.3389/fbioe.2020.617489 ◽

2021 ◽

Vol 8 ◽

Author(s):

Christopher Dartiailh ◽

Warren Blunt ◽

Parveen K. Sharma ◽

Song Liu ◽

Nazim Cicek ◽

...

Keyword(s):

Fatty Acids ◽

Tensile Strength ◽

Fatty Acid ◽

Pseudomonas Putida ◽

Chain Length ◽

Substrate Effect ◽

Mechanical And Thermal Properties ◽

Medium Chain ◽

Molecular Weights ◽

Medium Chain Length

Medium chain-length polyhydroxyalkanoates (mcl-PHA) were produced by Pseudomonas putida LS46 cultured with a variety of carbohydrate and fatty acid substrates. The monomer compositions and molecular weights of the polymers varied greatly and was dependent on whether the substrate was metabolized via the fatty acid degradation or the de novo fatty acid synthesis pathways. The highest molecular weights were obtained from medium chain-length fatty acids, whereas low molecular weights were obtained from longer chain-length and more unsaturated fatty acids or carbohydrates. The differences in monomer compositions and molecular weights due to the choice of substrate did not affect the polymer thermal degradation point. The glass transition temperatures varied from −39.4°C to −52.7°C. The melting points, when observed, ranged from 43.2°C to 51.2°C. However, a profound substrate effect was observed on the crystallinity of these polymers. Reduced crystallinity was observed when the monomer compositions deviated away from C8–C10 monomer lengths. The highest crystallinity was observed from medium chain-length fatty acids, which resulted in polymers with the highest tensile strength. The polymer produced from octanoic acid exhibited the highest tensile strength of 4.3 MPa with an elongation-at-break of 162%, whereas the polymers produced from unsaturated, long-chain fatty acids remained amorphous. A comparative analysis of the substrate effect on the physical-mechanical and thermal properties of mcl-PHAs better clarifies the relationship between the monomer composition and their potential applications, and also aids to direct future PHA synthesis research toward properties of interest.

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Identification and Characterization of a New Enoyl Coenzyme A Hydratase Involved in Biosynthesis of Medium-Chain-Length Polyhydroxyalkanoates in Recombinant Escherichia coli

Journal of Bacteriology ◽

10.1128/jb.185.18.5391-5397.2003 ◽

2003 ◽

Vol 185 (18) ◽

pp. 5391-5397 ◽

Cited By ~ 64

Author(s):

Si Jae Park ◽

Sang Yup Lee

Keyword(s):

Escherichia Coli ◽

Fatty Acid ◽

Chain Length ◽

Biosynthetic Pathway ◽

Pha Synthase ◽

Enzymatic Analysis ◽

E Coli ◽

Medium Chain ◽

Medium Chain Length ◽

Enoyl Coa Hydratase

ABSTRACT The biosynthetic pathway of medium-chain-length (MCL) polyhydroxyalkanoates (PHAs) from fatty acids has been established in fadB mutant Escherichia coli strain by expressing the MCL-PHA synthase gene. However, the enzymes that are responsible for the generation of (R)-3-hydroxyacyl coenzyme A (R3HA-CoAs), the substrates for PHA synthase, have not been thoroughly elucidated. Escherichia coli MaoC, which is homologous to Pseudomonas aeruginosa (R)-specific enoyl-CoA hydratase (PhaJ1), was identified and found to be important for PHA biosynthesis in a fadB mutant E. coli strain. When the MCL-PHA synthase gene was introduced, the fadB maoC double-mutant E. coli WB108, which is a derivative of E. coli W3110, accumulated 43% less amount of MCL-PHA from fatty acid compared with the fadB mutant E. coli WB101. The PHA biosynthetic capacity could be restored by plasmid-based expression of the maoCEc gene in E. coli WB108. Also, E. coli W3110 possessing fully functional β-oxidation pathway could produce MCL-PHA from fatty acid by the coexpression of the maoCEc gene and the MCL-PHA synthase gene. For the enzymatic analysis, MaoC fused with His6-Tag at its C-terminal was expressed in E. coli and purified. Enzymatic analysis of tagged MaoC showed that MaoC has enoyl-CoA hydratase activity toward crotonyl-CoA. These results suggest that MaoC is a new enoyl-CoA hydratase involved in supplying (R)-3-hydroxyacyl-CoA from the β-oxidation pathway to PHA biosynthetic pathway in the fadB mutant E. coli strain.

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