Acetone and Butanone Metabolism of the Denitrifying Bacterium "Aromatoleum aromaticum" Demonstrates Novel Biochemical Properties of an ATP-Dependent Aliphatic Ketone Carboxylase

Schühle, Karola; Heider, Johann

doi:10.1128/jb.05895-11

Cited by 37 publications

(62 citation statements)

References 26 publications

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“…A comparison between the acetone carboxylase of strain Py2 and the carboxylase of the phototrophic bacterium Rhodobacter capsulatus showed that they are identical in subunit composition (␣ 2 ␤ 2 ␥ 2 multimers of 85-, 78-, and 20-kDa subunits) and in kinetic properties (12,13). A similar subunit composition was recently found with the acetone carboxylase of the nitrate reducer Aromatoleum aromaticum (14) and with the acetone carboxylases of Alicycliphilus denitrificans, Paracoccus denitrificans, and Paracoccus pantotrophus (15). Thus, it appears to be well established that aerobic and nitrate-reducing bacteria activate acetone by an ATP-dependent carboxylation reaction.…”

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confidence: 64%

“…This ATP is perhaps needed to stabilize the enol tautomer of acetone in the form of acetone enolphosphate. This compound is the real substrate of carboxylation by the acetone carboxylases described in the past (14,34) and may as well be the real acceptor of CO in the carbonylation reaction proposed here. Since the reaction product, acetoacetaldehyde, is extremely reactive, it appears to be plausible that it is not released free into the cytoplasm but is immediately oxidized further to acetoacetyl-CoA, perhaps in a multienzyme complex.…”

Section: Discussionmentioning

confidence: 99%

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Carbonylation as a Key Reaction in Anaerobic Acetone Activation by Desulfococcus biacutus

Acosta

Hardt

Schink

2013

Appl Environ Microbiol

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Acetone is activated by aerobic and nitrate-reducing bacteria via an ATP-dependent carboxylation reaction to form acetoacetate as the first reaction product. In the activation of acetone by sulfate-reducing bacteria, acetoacetate has not been found to be an intermediate. Here, we present evidence of a carbonylation reaction as the initial step in the activation of acetone by the strictly anaerobic sulfate reducer Desulfococcus biacutus. In cell suspension experiments, CO was found to be a far better cosubstrate for acetone activation than CO 2 . The hypothetical reaction product, acetoacetaldehyde, is extremely reactive and could not be identified as a free intermediate. However, acetoacetaldehyde dinitrophenylhydrazone was detected by mass spectrometry in cell extract experiments as a reaction product of acetone, CO, and dinitrophenylhydrazine. In a similar assay, 2-amino-4-methylpyrimidine was formed as the product of a reaction between acetoacetaldehyde and guanidine. The reaction depended on ATP as a cosubstrate. Moreover, the specific activity of aldehyde dehydrogenase (coenzyme A [CoA] acylating) tested with the putative physiological substrate was found to be 153 ؎ 36 mU mg ؊1 protein, and its activity was specifically induced in extracts of acetone-grown cells. Moreover, acetoacetyl-CoA was detected (by mass spectrometry) after the carbonylation reaction as the subsequent intermediate after acetoacetaldehyde was formed. These results together provide evidence that acetoacetaldehyde is an intermediate in the activation of acetone by sulfate-reducing bacteria.A cetone is produced by bacterial fermentations, for example, by several Clostridium species (1). It is also produced in chemistry as a solvent and as an intermediate in the synthetic chemical industry. Aerobic degradation of methyl ketones was first observed with hydrocarbon-utilizing bacteria (2). Acetone is degraded by some aerobic bacteria (3) and mammalian liver cells via oxygenase-dependent hydroxylation to acetol (4). Carboxylation of acetone to acetoacetate as a means of acetone activation was first proposed for a methanogenic enrichment culture (5). The requirement of CO 2 as a cosubstrate for acetone degradation was also observed with the nitrate reducer Thiosphaera pantotropha (6) and with Rhodobacter capsulatus and other phototrophs (7). The reaction was studied with the nitrate-reducing strain Bun N under anoxic conditions, and it was concluded that acetoacetate was formed by the ATP-dependent carboxylation of acetone (8, 9).Attempts to measure an in vitro carboxylation of acetone at that time were unsuccessful. However, exchange of radioactively labeled CO 2 with the carboxyl group of acetoacetate was catalyzed by cell extracts of strain Bun N (10). A similar CO 2 -and ATPdependent activation reaction was observed with the aerobic bacterium Xanthobacter autotrophicus strain Py2 (11). A comparison between the acetone carboxylase of strain Py2 and the carboxylase of the phototrophic bacterium Rhodobacter capsulatus showed that they are ide...

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confidence: 64%

Section: Discussionmentioning

confidence: 99%

Carbonylation as a Key Reaction in Anaerobic Acetone Activation by Desulfococcus biacutus

Acosta

Hardt

Schink

2013

Appl Environ Microbiol

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“…Therefore, it is likely catalyzed by an enzyme annotated as ATP-dependent hydantoinase (39), whose genes are also part of the gene cluster (iaaCE). Hydantoinases of this family are similar to ATP-dependent acetone or acetophenone carboxylases (28,44,45) and are thought to activate the lactam group by ATP-dependent phosphorylation to the corresponding tautomeric phospholactim, which is easier to hydrolyze (Fig. 4).…”

Section: Resultsmentioning

confidence: 99%

Anaerobic Metabolism of Indoleacetate

et al. 2012

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The anaerobic metabolism of indoleacetate (indole-3-acetic acid [IAA]) in the denitrifying betaproteobacterium Azoarcus evansii was studied. The strain oxidized IAA completely and grew with a generation time of 10 h. Enzyme activities that transformed IAA were present in the soluble cell fraction of IAA-grown cells but were 10-fold downregulated in cells grown on 2-aminobenzoate or benzoate. The transformation of IAA did not require molecular oxygen but required electron acceptors like NAD + or artificial dyes. The first products identified were the enol and keto forms of 2-oxo-IAA. Later, polar products were observed, which could not yet be identified. The first steps likely consist of the anaerobic hydroxylation of the N-heterocyclic pyrrole ring to the enol form of 2-oxo-IAA, which is catalyzed by a molybdenum cofactor-containing dehydrogenase. This step is probably followed by the hydrolytic ring opening of the keto form, which is catalyzed by a hydantoinase-like enzyme. A comparison of the proteome of IAA- and benzoate-grown cells identified IAA-induced proteins. Owing to the high similarity of A. evansii with strain EbN1, whose genome is known, we identified a cluster of 14 genes that code for IAA-induced proteins involved in the early steps of IAA metabolism. These genes include a molybdenum cofactor-dependent dehydrogenase of the xanthine oxidase/aldehyde dehydrogenase family, a hydantoinase, a coenzyme A (CoA) ligase, a CoA transferase, a coenzyme B 12 -dependent mutase, an acyl-CoA dehydrogenase, a fusion protein of an enoyl-CoA hydratase and a 3-hydroxyacyl-CoA dehydrogenase, a beta-ketothiolase, and a periplasmic substrate binding protein for ABC transport as well as a transcriptional regulator of the GntR family. Five predicted enzymes form or act on CoA thioesters, indicating that soon after the initial oxidation of IAA and possibly ring opening, CoA thioesters are formed, and the carbon skeleton is rearranged, followed by a CoA-dependent thiolytic release of another CoA thioester. We propose a scheme of an anaerobic IAA metabolic pathway that ultimately leads to 2-aminobenzoyl-CoA or benzoyl-CoA.

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“…Acetone carboxylase (Acx) is a member of a protein family that also contains acetophenone carboxylase and ATPdependent hydantoinases/oxoprolinases. While the members of this family share several similar characteristics, they differ with respect to the substrates, the products of ATP hydrolysis, and structural properties (16).…”

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confidence: 99%

“…The only known paralogous enzyme with similar biochemical function is acetophenone carboxylase from Aromatoleum aromaticum (16). This enzyme consists of a hetero-octamer of four subunits whose corresponding genes apcABCDE are clustered as an operon.…”

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confidence: 99%

Purification and Characterization of the Acetone Carboxylase of Cupriavidus metallidurans Strain CH34

Rosier

Leys

Henoumont

et al. 2012

Appl Environ Microbiol

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ABSTRACTAcetone carboxylase (Acx) is a key enzyme involved in the biodegradation of acetone by bacteria. Except for theHelicobacteraceaefamily, genome analyses revealed that bacteria that possess an Acx, such asCupriavidus metalliduransstrain CH34, are associated with soil. The Acx of CH34 forms the heterohexameric complex α2β2γ2and can carboxylate only acetone and 2-butanone in an ATP-dependent reaction to acetoacetate and 3-keto-2-methylbutyrate, respectively.

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Acetone and Butanone Metabolism of the Denitrifying Bacterium "Aromatoleum aromaticum" Demonstrates Novel Biochemical Properties of an ATP-Dependent Aliphatic Ketone Carboxylase

Cited by 37 publications

References 26 publications

Carbonylation as a Key Reaction in Anaerobic Acetone Activation by Desulfococcus biacutus

Carbonylation as a Key Reaction in Anaerobic Acetone Activation by Desulfococcus biacutus

Anaerobic Metabolism of Indoleacetate

Purification and Characterization of the Acetone Carboxylase of Cupriavidus metallidurans Strain CH34

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