Ethanolamine Utilization

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Ethanolamine utilization refers to the biochemical processes and applications involving ethanolamine, an organic compound that serves as a building block for phospholipids and is involved in various metabolic pathways. This field encompasses its role in cellular functions, industrial applications, and potential therapeutic uses.

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Key research themes

1. How do bacterial microcompartments and extracellular electron transfer systems facilitate anaerobic ethanolamine utilization in pathogens?

This research theme focuses on the molecular and physiological mechanisms by which bacteria, particularly human pathogens like Listeria monocytogenes, utilize ethanolamine (EA) under anaerobic conditions. The investigation centers on the role of bacterial microcompartments (BMCs) that encapsulate ethanolamine catabolic enzymes and the involvement of extracellular electron transfer (EET) systems, particularly flavin-based EET, in maintaining redox balance and supporting growth. These mechanisms are critical for pathogen survival and virulence in nutrient-limited and anaerobic environments such as the human gastrointestinal tract, making them of interest for understanding bacterial metabolism and potential therapeutic targeting.

Bacterial Microcompartments Coupled with Extracellular Electron Transfer Drive the Anaerobic Utilization of Ethanolamine in Listeria monocytogenes

by Varaang Bhandula

2022, mSystems

Key finding: The study demonstrated that Listeria monocytogenes forms ethanolamine-utilizing bacterial microcompartments (eut BMCs) under anaerobic conditions, converting EA predominantly into acetate and ethanol in a 2:1 molar ratio.... Read more

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2. What is the role of acetaldehyde metabolism and aldehyde dehydrogenase (ALDH2) activation in modulating ethanol intake and its neurobehavioral effects?

This theme investigates the metabolic and neuropharmacological contributions of acetaldehyde, the primary ethanol metabolite, in modulating ethanol's reinforcing properties, intake behavior, and toxicity. It particularly emphasizes the role of aldehyde dehydrogenase-2 (ALDH2) in acetaldehyde catabolism within the central nervous system, exploring pharmacological activation of ALDH2 as a strategy to attenuate ethanol intake. Understanding these metabolic pathways is essential for developing treatments for alcohol use disorders by targeting acetaldehyde bioavailability and its neurobehavioral effects.

Activation of mitochondrial aldehyde dehydrogenase (ALDH2) by ALDA-1 reduces both the acquisition and maintenance of ethanol intake in rats: A dual mechanism?

by David Felipe Vásquez

2024, Neuropharmacology

Key finding: This study established that systemic administration of ALDA-1, an activator of mitochondrial ALDH2, significantly enhanced brain ALDH2 enzymatic activity threefold, which led to a pronounced reduction in the acquisition of... Read more

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Mystic Acetaldehyde: The Never-Ending Story on Alcoholism

by Patrizia Romualdi

2023, Frontiers in behavioral neuroscience

Key finding: This comprehensive review synthesizes decades of research on acetaldehyde’s central and peripheral effects, highlighting its reinforcing properties independent of ethanol itself. It underscores behavioral and pharmacological... Read more

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Increase in nucleus accumbens dopamine levels following local ethanol administration is not mediated by acetaldehyde

by B. Söderpalm

2023, Alcohol and alcoholism (Oxford, Oxfordshire)

Key finding: Using in vivo microdialysis in rat nucleus accumbens, this study showed that direct local ethanol perfusion raised extracellular dopamine levels; however, neither local administration of acetaldehyde nor systemic... Read more

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3. How can modulation of glutamatergic and monoaminergic transporter systems influence ethanol self-administration and potential treatment strategies for alcohol use disorder?

This line of research examines the neurochemical mechanisms underlying ethanol intake, focusing on the role of transporter proteins such as organic cation transporter 3 (OCT3) and the cystine-glutamate antiporter (system x_c−). It evaluates how ethanol affects monoamine uptake via these transporters, influences glutamate homeostasis, and how pharmacological modulation (e.g., N-acetylcysteine) affects ethanol-related behaviors. These insights inform development of novel pharmacotherapeutics targeting transporter systems to reduce ethanol self-administration and relapse in alcohol use disorder.

Ethanol inhibits dopamine uptake via organic cation transporter 3: Implications for ethanol and cocaine co-abuse

by Diethart Schmid

2023, Molecular Psychiatry

Key finding: This study revealed that ethanol inhibits monoamine uptake not via classical transporters (DAT, NET, SERT) but selectively through organic cation transporter 3 (OCT3). Using OCT3 knockout mice and in vivo electrochemical... Read more

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Evaluation of N-acetylcysteine on ethanol self-administration in ethanol-dependent rats

by Catherine Vilpoux

2024, Neuropharmacology

Key finding: Chronic intermittent ethanol vapor exposure established dependence in rats, which showed elevated ethanol self-administration, seeking, motivation, and relapse. Administration of N-acetylcysteine (NAC) at low doses... Read more

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All papers in Ethanolamine Utilization

Novel Pyrophosphate-Forming Acetate Kinase from the Protist Entamoeba histolytica

by Cheryl Ingram-Smith

2022, Eukaryotic Cell

Acetate kinase (ACK) catalyzes the reversible synthesis of acetyl phosphate by transfer of the γ-phosphate of ATP to acetate. Here we report the first biochemical and kinetic characterization of a eukaryotic ACK, that from the protist... more

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Characterization of Escherichia coli EutD: a phosphotransacetylase of the ethanolamine operon

by Carlos Andreo

2021, The Journal of Microbiology

Three Escherichia coli genes (maeB, pta, and eutD) encode proteins with the PTA_PTB domain found in phosphate acetyltransferases and butaryltransferases. MaeB is a NADPdependent malic enzyme, which contains the PTA_PTB domain at the... more

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The 2-Aminoethylphosphonate-Specific Transaminase of the 2-Aminoethylphosphonate Degradation Pathway

by Barry Wanner

2016, Journal of Bacteriology

The 2-aminoethylphosphonate transaminase (AEPT; the phnW gene product) of the Salmonella enterica serovar Typhimurium 2-aminoethylphosphonate (AEP) degradation pathway catalyzes the reversible reaction of AEP and pyruvate to form... more

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Characterization of Escherichia coli EutD: a phosphotransacetylase of the ethanolamine operon

by Carlos Andreo and

2016, The Journal of Microbiology

Fig. 1. (A) Gene organization of the E. coli eut operon. Genes of the eut operon are directly or indirectly involved in ethanolamine catabolism: eutl and eutC encode the large and small subunits of ethanolamine ammonia lyase (EutBC), respectively, and eutE codes for an acetaldehyde dehydrogenase (EutE). Genes eutK, eutL, eutM, eutN, and eutS are thought to be involved in the assembly of the metabolosome. An insertior element that disrupts genes of the ewt operon in certain E. coli strains is also shown (Blattner et al., 1997; Hayashi et al., 2006). The product of the eutD gene (in grey) is characterized in the present work. (B) Enzymes involved in ethanolamine and acetate utilization in E. coli. EutBC and EutE enzymes participate in ethanolamine degradation and are located in the metabolosome. Two cytosolic pathways of acetate activation and productior can be found in E. coli: Acs catalyzes an irreversible pathway for high-affinity acetate activation, while AckA and Pta catalyze a reversible pathway involved in acetate production or assimilation at high acetate concentration. EutD (in grey) could be located in the metabolosome or in the cytosol.

Fig. 3. (A) Coomassie Blue-stained SDS polyacrylamide gels of total protein extracts from induced AG1/p-EutD E. coli strain (Lane 1, 10 pg), Ni-NTA column wash fraction (Lane 2, 5 wg) and purified recombinant E. coli EutD (Lane 3, 5 yg). The estimated molecular mass of EutD is indicated on the right. Molecular mass markers (MM) were run on the left. (B) pH-dependent phosphotransacetylase activity of purified EutD. Activity is shown as a % of the maximum, obtained at pH 7.8.

Fig. 4. Regulatory properties of recombinant EcEutD in the acetyl-P forming direction. The acetyl-P forming activity of EcEutD (Fig. 1B) was monitored in the absence or presence of 5 mM NADH, ATP, Asp or PEP and different pyruvate concentrations. Substrate concent- rations were maintained at the Km value for each enzyme (Table 1). Results are presented as the ratio between % of activity in the presence of the effectors relative to the activity measured or in their absence. Assays were performed at least in triplicate, and error bars indicate SD. E. coli employs two different pathways for conversion of acetate into acetyl-CoA (Wolfe, 2005; El-Mansi et al., 2006; Kumari et al., 2007). The high-affinity pathway involves acetyl-

Fig. 5. EutD can restore growth of a pfa acs mutant strain on acetate as sole carbon source. Growth of pfa acs mutant strain (4), pta acs transformed with p-Pta (@), and pta acs transformed with p-EutD (©) on minimal medium with the addition of the indicated acetate concentration and in the presence of IPTG. ODgo9 was measured after a 40 h growth at 30°C.

Fig. 2. Amino acid sequence comparison of EcPta and EcEutD. (A) Numerals at the top indicate the length and domain location for each protein. In boxes, the putative conserved domains (CDD, conserved domain database for protein classification, Marchler-Bauer et al., 2009) in EcPta: P-loop NTPase domain; DRTGG domain and PTA_PTB domain (Campos-Bermudez ef al., 2010). EutD is composed only by the PTA_PTB domain. (B) EcPta and EcEutD sequences were aligned using CLUSTAL W (1.82). Results indicate similarity between them when comparing a stretch of approximately 400 amino acids in the C-terminus of Pta and the complete EutD sequence.

“Sigmoidal kinetic reaction (Hill coefficient: 1.7; Campos-Bermudez et al., 2010). > Sigmoidal kinetic reaction (Hill coefficient: 1.3; Campos-Bermudez et al., 2010) Table 1. Kinetic parameters for the acetyl-CoA and acetyl-P forming reactions of E. coli EutD (EcEutD). Kinetic values are given as Mean+SD Each value is averaged over at least two different enzyme preparations. Ac-P: acetyl-P. *The values obtained for EcPta (EcPta; Campos-Bermudez et al., 2010) are included for comparison.

“strain BW25113 obtained from the NIG Collection (Baba et al., 2006) Culture medium contained M9 salts supplemented with 30 mM acetate, 10 mM ethanolamine or 150 uM vitamin B12 (vitB12) as indicated. Final O.D. values obtained after a 40 h growth at 30°C are shown. Results are the mean of at least three independent experiments.

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Characterization of Escherichia coli EutD: a phosphotransacetylase of the ethanolamine operon

by Carlos Andreo

2016, The Journal of Microbiology

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Functional dissection of Escherichia coli phosphotransacetylase structural domains and analysis of key compounds involved in activity regulation

by Carlos Andreo

2016, FEBS Journal

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Acetate excretion during growth of Salmonella enterica on ethanolamine requires phosphotransacetylase (EutD) activity, and acetate recapture requires acetylCoA synthetase (Acs) and phosphotransacetylase (Pta) activities

by Jorge Escalante-Semerena

2016, Microbiology-sgm

This report shows that Salmonella enterica catabolizes ethanolamine to acetyl-CoA (Ac-CoA), which enters the glyoxylate bypass and tricarboxylic acid cycle for the generation of energy and central metabolites. During growth on... more

Fig. 1. Acyl-CoA synthesis from ethanolamine and 1,2- propanediol. The first step in ethanolamine or 1,2-propanediol catabolism is catalysed by a coenzyme B,o-dependent enzyme that yields acetaldehyde or propionaldehyde, followed by an oxidation to the corresponding short-chain fatty acid, which is released as either acetyl- or propionyl-CoA. EutBC, coenzyme Byo-dependent ethanolamine ammonia-lyase (EC 4.3.1.7; Babior, 1982; Faust et a/., 1990); EutE, putative acetaldehyde dehydrogenase (Roof & Roth, 1989; Stojiljkovic et a/., 1995); PduCDE, 1,2-propanediol dehydratase (EC 4.2.1.28; Bobik et al., 1997); PduP, propionaldehyde dehydrogenase (Leal et a/., 2003).

Fig. 2. S. enterica gene functions needed to convert ethanolamine to acetate. (a) Genes encoding proteins with a known or putative enzymic activity are indicated as such. Genes encoding proteins with homology to cyanobacterial carboxysome proteins are labelled with vertical arrows. Horizontal arrows above the operon identify the two transcripts encoded at this locus. EutR is the activator of transcription of the eut operon. (b) Pathways for acetate activation in S. enterica. Depending on the external concentration of acetate, S. enterica uses either of two independent pathways to convert acetate to Ac-CoA. Low concentrations (<10 mM) of acetate require AMP-forming synthetase (Acs) activity (right); at >25 mM, acetate is converted to Ac-CoA by the acetate kinase (Ack) and phosphotransacetylase (Pta, EutD) enzymes (left).

Fig. 3. Acs and Pta activities are required for acetate excretion recapture. (a) acs* pta*, strain TR6583; (b) pta, strain JE6317 (pta103::cat*). (c) Aacs2 pta*, strain JE7758. (d) Aacs2 pta103::cat*, strain JE8821. Ml, Cell density; A, acetate con- centration in the medium.

Fig. 4. Ack activity is required for acetate excretion. Strain JE8749 (Aack103) carrying an in-frame deletion of the ack gene was used for this experiment. I, Cell density; A, acetate concentration in the medium.

Fig. 5. The EutD/Ack pathway is needed for optimal growth on ethanolamine, but it is not essential. Differences in growth rate and cell yield between wild-type and eutD strains were cor- rected by introducing a wild-type allele of eutD on a plasmid (pEUTD2). This plasmid carried a wild-type allele of eutD under the control of the arabinose-inducible promoter in plasmid pBAD30 (Guzman et al., 1995); 200 uM L(+)-arabinose was added to the medium to induce eutD expression. Strains used: eut*, strain TR6583; eutE, strain JE2236 (eutE18::MudA); eutD, strain JE7310 (AeutD1143); eutD pta, strain JE7437 (AeutD1143 pta103::cat*); eutD/peutD*, strain JE7375 [AeutD1143/pEUTD2 (blat P.aBap-eutD*)]; pta eutD/peutD™ , strain JE7439 [AeutD1143 pta03::cat*/pEUTD2 (blat ParaBA p-eutD © )I- Although the absence of EutD activity only slightly affected growth of S. enterica on ethanolamine, in the absence of this

Fig. 6. EutD phosphotransacetylase activity is required for acetate excretion during growth on ethanolamine. Lack of Acs activity in an eutD strain triggers acetate excretion. (a) eutD, strain JE7310 (AeutD1143); (b) eutD pta, strain JE7437 (AeutD1143 pta103::cat*); (c) eutD pta Aacs, strain JE8507 (AeutD1143 pta103::cat* Aacs2). Ml, Cell density; A, acetate concentration in the medium. One plausible answer to this question may lie in part in the kinetic differences between these enzymes. Although the S. enterica Pta enzyme (SePta) has not been isolated and characterized, its close relative from Escherichia coli (EcPta) has (Brinsmade & Escalante-Semerena, 2004; Shimizu et al., 1969; Suzuki, 1969). The EutD enzyme has a sevenfold higher affinity for CoA than does EcPta (46 vs 320 1M), a 23-fold higher affinity for Ac-P than does EcPta (0-13 vs 3 mM), and a 10-fold higher specific activity than that reported for EcPta (3044 vs 333). Relative to EcPta (and, by extrapolation, to SePta), EutD is a very efficient enzyme (Brinsmade & Escalante-Semerena, 2004; Shimizu et al., 1969; Suzuki, 1969). The high affinity of EutD for Ac-CoA and its presumable location within the ethanolamine meta- bolosome is proposed to prevent a non-physiological build- up of Ac-CoA, leading to a release of CoA and acetate and the concomitant production of ATP via substrate-level phosphorylation. Acetate excretion may help the cell mini- mize the negative effect of intracellular acetate accumulation on the pool of glutamate and other unidentified ions (Roe et al., 1998; Russell & Diez-Gonzalez, 1998). Relief from the toxic effects of acetate during growth on ethanolamine would be reached when the acetate switch is flipped towards acetate assimilation. We used the protein sequence of Saccharomyces cerevisiae Ac-CoA hydrolase (Ach1p) (Buu et al., 2003) to search for genes of Salmonella enterica encoding homologous proteins. The search yielded open reading frame STM3118 as the only gene possibly encoding a structural orthologue of Achlp Ac-CoA hydrolase. We constructed an in-frame deletion of STM3118 in strain JE7498 (eutD acs pta) and studied the growth behaviour and acetate excretion pattern in the resulting strain (JE7715). In addition to growing on ethanol- amine to wild-type levels, strain JE7715 excreted as much acetate as did its parent strain JE7498, indicating that STM3118 was not involved in acetate excretion in a strain lacking Acs, EutD and Pta activities (data not shown). This result does not rule out the existence of non-orthologous replacements of Achlp Ac-CoA hydrolase in S. enterica, a possibility that has not been investigated. Inactivation of either poxB or ack did not prevent acetate excretion in strains JE7832 (poxB acs pta eutD) or strain JE8326 (eutD acs

Fig. 7. Model for ethanolamine degradation in S. enterica. The size of the ethanolamine metabolosome is not to scale.

IM, GHC CLOCK TCHel, TAI S. enterica strains used in this study were derivatives of S. enterica serovar Typhimurium LT2. +In the text, Mud1-8 is referred to as MudA. §Tn10d(tet*) is an abbreviation of TnIOA16A17 (Wav et al.. 1984). Unless otherwise stated, strains listed were constructed during the course of this work.

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In Vivo and in Vitro Analyses of Single-amino Acid Variants of the Salmonella enterica Phosphotransacetylase Enzyme Provide Insights into the Function of Its N-terminal Domain

by Jorge Escalante-Semerena

2016, Journal of Biological Chemistry

High affinity pathway: [1] Acetate + ATP ↔ Acetyl-AMP + PP i Acetyl-AMP + CoASH ↔ Ac-CoA + AMP Catalyzed by Ac-CoA synthetase (Acs, E.C. 6.2.1.1) Low affinity pathway: [2] Acetate + ATP ↔ Ac-P + ADP ΔGº'obs = -13 kJ/mol (1) Catalyzed by... more

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Cloning, characterization and functional expression of an alkalitolerant type C feruloyl esterase from Fusarium oxysporum

by Carlos Solis

2015, Applied Microbiology and Biotechnology

ABSTRACT A hypothetical protein FoFaeC-12213 of Fusarium oxysporum was found to have high amino acid sequence identity with known type C feruloyl esterases (FAEs) containing a 13-amino acid conserved region flanking the characteristic... more

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Biochemical and Kinetic Characterization of the Eukaryotic Phosphotransacetylase Class IIa Enzyme from Phytophthora ramorum

by Kerry Smith and

2015

Phosphotransacetylase (Pta), a key enzyme in bacterial metabolism, catalyzes the reversible transfer of an acetyl group from acetyl phosphate to coenzyme A (CoA) to produce acetyl-CoA and P i . Two classes of Pta have been identified... more

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Characterization of Escherichia coli EutD: a phosphotransacetylase of the ethanolamine operon

by Damian Saavedra

2014, Journal of Microbiology

The Escherichia coli genes pta and eutD encode proteins containing the phosphate-acetyltransferase domain. EutD is composed only by this domain and belongs to the ethanolamine operon. This enzyme has not been characterized yet, and its... more

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Characterization of Escherichia coli EutD: a phosphotransacetylase of the ethanolamine operon

by Scarlet Wolf

2014, Journal of Microbiology

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Characterization of Escherichia coli EutD: a phosphotransacetylase of the ethanolamine operon

by Damian Saavedra

2013, Journal of Microbiology

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