Partial Purification and Some Properties of an Aromatic-amino-acid and an Aspartate Aminotransferase in Brevibacterium linens 47

Lee, Chang-Won; Desmazeaud, M.

doi:10.1099/00221287-131-3-459

Cited by 16 publications

(18 citation statements)

References 19 publications

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“…This two-step metabolic sequence has been demonstrated in lactococci (17). An aminotransferase has been identified in Lactococcus lactis (32), and two aminotransferases have been partially purified from B. linens (21). In Saccharomyces cerevisiae, the genes encoding aminotransferase in the genome fall into the following three groups: (i) ScAAT1 and ScAAT2, encoding aspartate amino acid aminotransferases (11,23,29); (ii) ScBCA1, encoding a branched-chain amino acid aminotransferase (15); and (iii) ScARO8 and ScARO9, encoding aromatic amino acid aminotransferases (20,28).…”

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l -Methionine Degradation Pathway in Kluyveromyces lactis : Identification and Functional Analysis of the Genes Encoding l -Methionine Aminotransferase

Kagkli

Bonnarme

Neuvéglise

et al. 2006

Appl Environ Microbiol

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Kluyveromyces lactis is one of the cheese-ripening yeasts and is believed to contribute to the formation of volatile sulfur compounds (VSCs) through degradation of L-methionine. L-Methionine aminotransferase is potentially involved in the pathway that results in the production of methanethiol, a common precursor of VSCs. Even though this pathway has been studied previously, the genes involved have never been studied. In this study, on the basis of sequence homology, all the putative aminotransferase-encoding genes from K. lactis were cloned in an overproducing vector, pCXJ10, and their effects on the production of VSCs were analyzed. Two genes, KlARO8.1 and KlARO8.2, were found to be responsible for L-methionine aminotransferase activity. Transformants carrying these genes cloned in the pCXJ10 vector produced threefold-larger amounts of VSCs than the transformant containing the plasmid without any insert or other related putative aminotransferases produced.

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confidence: 99%

l -Methionine Degradation Pathway in Kluyveromyces lactis : Identification and Functional Analysis of the Genes Encoding l -Methionine Aminotransferase

Kagkli

Bonnarme

Neuvéglise

et al. 2006

Appl Environ Microbiol

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“…It has been suggested that in the oenological bacterium Oenococcus oeni, the transamination of L-methionine is the first step in the pathway for degradation of L-methionine to VSCs (16). In B. linens, one aromatic amino acid aminotransferase and one aspartate aminotransferase were partially purified and characterized (11), but neither of these enzymes was tested with L-methionine as the transamination substrate. A transamination pathway was also suggested for several cheese-ripening yeasts, including G. candidum (7), as well as for the brewing yeast Saccharomyces cerevisiae (15), and this pathway could be involved in VSC production in such microorganisms.…”

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confidence: 99%

Evidence for Distinct l -Methionine Catabolic Pathways in the Yeast Geotrichum candidum and the Bacterium Brevibacterium linens

Arfi

Landaud

Bonnarme

2006

Appl Environ Microbiol

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Tracing experiments were carried out to identify volatile and nonvolatile L-methionine degradation intermediates and end products in the yeast Geotrichum candidum and in the bacterium Brevibacterium linens, both of which are present in the surface flora of certain soft cheeses and contribute to the ripening reactions. Since the acid-sensitive bacterium B. linens is known to produce larger amounts and a greater variety of volatile sulfur compounds (VSCs) than the yeast G. candidum produces, we examined whether the L-methionine degradation routes of these microorganisms differ. In both microorganisms, methanethiol and ␣-ketobutyrate are generated; the former compound is the precursor of other VSCs, and the latter is subsequently degraded to 2,3-pentanedione, which has not been described previously as an end product of L-methionine catabolism. However, the L-methionine degradation pathways differ in the first steps of L-methionine degradation. L-Methionine degradation is initiated by a one-step degradation process in the bacterium B. linens, whereas a two-step degradation pathway with 4-methylthio-2-oxobutyric acid (MOBA) and 4-methylthio-2-hydroxybutyric acid (MHBA) as intermediates is used in the yeast G. candidum. Since G. candidum develops earlier than B. linens during the ripening process, MOBA and MHBA generated by G. candidum could also be used as precursors for VSC production by B. linens.Traditional fermented products result from the action of a set of microorganisms that give these products their diversity, their uniqueness, and their quality. In this context, sulfur compounds play a key role (18). Owing to their low detection thresholds and their strong reactivity, volatile sulfur compounds (VSCs) significantly influence the quality and unique flavor characteristics of many foodstuffs, such as cheese, wine, and beer (15,16,20). VSCs essentially arise from degradation of the sulfur-carbon bond of the amino acid precursor L-methionine, giving rise to methanethiol (MTL), a common precursor of VSCs (5).A large number of microorganisms, including yeasts and bacteria, are employed in traditional food processing, such as cheese ripening and wine and beer making, and are often used in association with each other. In soft cheeses, yeasts (e.g., Geotrichum candidum) develop in the early stages of cheese ripening and participate in the deacidification of the curd and, to a lesser extent, in aromatization (2). In contrast, acidsensitive surface bacteria (e.g., Brevibacterium linens) develop much later than yeasts during ripening, once the pH is sufficiently raised by the deacidifying yeast (3). B. linens is known to produce consistent amounts of VSCs (8, 9). L-Methionine ␥-lyase (MGL) catalyzes the one-step degradation of L-methionine to MTL, ␣-ketobutyrate (␣-KB), and ammonium, and the gene encoding this enzyme in B. linens has been identified recently (1). In contrast, lactic acid bacteria (LAB) poorly convert L-methionine to VSCs (9) because they possess Met aminotransferase but no MGL activity. It therefore seem...

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“…High activities toward dicarboxylic substrates characterized also ArATs isolated from other sources. The activity of ArAT from Escherichia coli toward l -aspartate reached 65 % of the maximum activity determined with l -tyrosine (Powell and Morrison 1978), and activity of ArAT from Brevibacterium linens toward l -aspartate reached 50 % of the maximum activity determined with l -phenylalanine (Lee and Desmazeaud 1985). For comparison, aspartate aminotransferases studied in parallel with ArATs by Powell and Morrison (1978) and Lee and Desmazeaud (1985) were characterized by considerably different relative activities toward amino acid substrates.…”

Section: Resultsmentioning

confidence: 99%

tyrB-2 and phhC genes of Pseudomonas putida encode aromatic amino acid aminotransferase isozymes: evidence at the protein level

Szkop

Bielawski

2013

Amino Acids

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Two Pseudomonas putida aminotransferases (ArAT I and ArAT II) that exhibit activity toward l-tryptophan were purified 104- and 395-fold using a six-stage purification procedure involving ammonium sulfate fractionation and chromatographic separation on phenyl-Sepharose, Sephadex G-100 superfine, DEAE-cellulose and Protein-Pack Q8 HR columns. Mass spectrometry analysis resulted in the identification of 27 and 20 % of the total ArAT I and ArAT II amino acid sequences. In addition, N-terminal sequence fragments of ArAT I and ArAT II were determined using the Edman degradation method. Based on the analyses performed, the studied proteins were identified as products of the tyrB-2 and phhC genes, and the presence of these genes in the investigated bacterial strain was confirmed using molecular biology methods. Extensive analysis of the substrate specificities of ArAT I and ArAT II revealed that both enzymes most efficiently catalyzed reactions involving aromatic amino acids and 2-oxoacids followed by dicarboxylic compounds. The best substrates for ArAT I and ArAT II were l-phenylalanine and phenylpyruvate. Based on these results, the studied proteins were classified as aromatic amino acid aminotransferase isozymes.

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Partial Purification and Some Properties of an Aromatic-amino-acid and an Aspartate Aminotransferase in Brevibacterium linens 47

Cited by 16 publications

References 19 publications

l -Methionine Degradation Pathway in Kluyveromyces lactis : Identification and Functional Analysis of the Genes Encoding l -Methionine Aminotransferase

l -Methionine Degradation Pathway in Kluyveromyces lactis : Identification and Functional Analysis of the Genes Encoding l -Methionine Aminotransferase

Evidence for Distinct l -Methionine Catabolic Pathways in the Yeast Geotrichum candidum and the Bacterium Brevibacterium linens

tyrB-2 and phhC genes of Pseudomonas putida encode aromatic amino acid aminotransferase isozymes: evidence at the protein level

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