Identification and characterization of a cystathionine β/γ-lyase from Lactococcus lactis ssp. cremoris MG1363

Dobric, N

doi:10.1016/s0378-1097(99)00599-6

Cited by 17 publications

(33 citation statements)

References 27 publications

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“…Taking the results together, we concluded that MetC catalyzes both an ␣,␤-and an ␣,␥-elimination reaction. This property has also been reported for the CBL of L. lactis (1,15).…”

Section: Vol 74 2008 Two L Casei Genes Encoding a Cystathionine Lysupporting

confidence: 80%

Cloning and Characterization of Two Lactobacillus casei Genes Encoding a Cystathionine Lyase

Irmler

Raboud

Beisert

et al. 2008

Appl Environ Microbiol

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Volatile sulfur compounds are key flavor compounds in several cheese types. To better understand the metabolism of sulfur-containing amino acids, which certainly plays a key role in the release of volatile sulfur compounds, we searched the genome database of Lactobacillus casei ATCC 334 for genes encoding putative homologs of enzymes known to degrade cysteine, cystathionine, and methionine. The search revealed that L. casei possesses two genes that putatively encode a cystathionine ␤-lyase (CBL; EC 4.4.1.8). The enzyme has been implicated in the degradation of not only cystathionine but also cysteine and methionine. Recombinant CBL proteins catalyzed the degradation of L-cystathionine, O-succinyl-L-homoserine, L-cysteine, L-serine, and L-methionine to form ␣-keto acid, hydrogen sulfide, or methanethiol. The two enzymes showed notable differences in substrate specificity and pH optimum.Volatile sulfur compounds (VSC) are found in many cheese varieties and are important components of flavor (10). The sulfur compounds methanethiol, methional, and dimethyl trisulfide (DMTS) are key odorants of Swiss Gruyère cheese flavor and are presumably derived from the bacterial metabolism of methionine, which is present in caseins at higher concentrations than cysteine. Swiss Gruyère (place of designated origin) cheese is produced with thermophilic mixed-strain starters which usually contain Streptococcus thermophilus and Lactobacillus delbrueckii subsp. lactis. In addition, depending on the cheese factory, Lactobacillus helveticus can also be present. However, after ripening, Lactobacillus casei and Lactobacillus rhamnosus bacteria are found in high numbers (8). Interestingly, L. casei is also a constituent of the nonstarter lactic acid bacteria of many other cheese varieties (6). Therefore, this species is considered to play an important role during ripening and may be a key player in the formation of flavor compounds.The catabolic pathway(s) of methionine and cysteine in lactobacilli is not well characterized. Possible pathways involve transaminases, methionine ␥-lyases, cystathionine ␤-lyases (CBL), and cystathionine ␥-lyases (CGL) (13). The transamination of methionine by aminotransferases has been studied in lactococci (18,27,34). The results of these studies suggested that methionine is converted to 2-oxo-4-methylthiobutyric acid, which is then converted, either enzymatically or chemically, to methanethiol. In Brevibacterium linens, a methionine ␥-lyases which catalyzes the deamination of methionine and releases methanethiol has been identified and the corresponding gene has been cloned (2,14).CBL, which is encoded by the gene metC in Escherichia coli, is involved in the ␣,␤-elimination of cystathionine to form homocysteine, pyruvate, and ammonia. In comparison, CGL catalyzes the ␣,␥-elimination reaction of cystathionine, producing cysteine, ammonia, and ␣-ketobutyrate. CBL and CGL generally show catalytic promiscuity, which means that they catalyze different reactions. Thus, the CBL from Lactococcus lactis subsp. cremor...

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“…Taking the results together, we concluded that MetC catalyzes both an ␣,␤-and an ␣,␥-elimination reaction. This property has also been reported for the CBL of L. lactis (1,15).…”

Section: Vol 74 2008 Two L Casei Genes Encoding a Cystathionine Lysupporting

confidence: 80%

Cloning and Characterization of Two Lactobacillus casei Genes Encoding a Cystathionine Lyase

Irmler

Raboud

Beisert

et al. 2008

Appl Environ Microbiol

View full text Add to dashboard Cite

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“…Only low quantities of VSC were produced by LAB when cultivated alone. LAB and mainly L. lactis, the major species in our starter mixture, was found to possess two enzymes, cystathionine β-lyase and cystathionine γ -lyase, which were able to convert L-methionine to methanethiol [2,16]. However, these enzymes exhibit low specificity towards L-methionine.…”

Section: Discussionmentioning

confidence: 99%

Contribution of several cheese-ripening microbial associations to aroma compound production

Arfi

Leclercq-Perlat

Baucher

et al. 2004

Lait

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-The aromatic potential of various cocultures of yeasts, Brevibacterium linens and lactic acid bacteria (LAB) was studied in cheese-based medium. Three yeasts (Debaryomyces hansenii, Geotrichum candidum and Kluyveromyces lactis) were cultivated in association with B. linens, in the presence or in the absence of LAB -added as the commercial lactic acid starter Flora Danica ® . Various parameters were analysed such as aroma compound production, the growth of each microorganism and lactose/lactate degradation. All tested yeasts could grow in all the associations regardless of the presence or the absence of LAB. LAB enhanced the growth of B. linens in D. hansenii associations, but they reduced B. linens' growth when associated with K. lactis. When cultivated alone, LAB produced very few aroma compounds and in lesser amount than the yeast-B. linens associations. In pure cultures of LAB, ethanol was the major volatile compound, and only scanty amounts of other volatile compounds were produced. The K. lactis-B. linens association exhibited the most diversified aroma compound profile with high quantities of S-methyl thioacetate and ethyl acetate. LAB promoted the synthesis of volatile sulphur compounds in this association.

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“…Two enzymatic pathways in lactococci have been postulated. In the first one, a single-step route, a lyase (cystathionine ␤-or ␥-lyase), catalyzes the simultaneous deamination and demethylthiolation of Met to MTL (2,10,14,17). In Brevibacterium linens, disruption of the mgl gene encoding L-methionine ␥-lyase, which catalyzes the ␣,␥-elimination of Met to MTL, almost eliminated this strain's considerable capacity to produce VSCs (3).…”

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confidence: 99%

YtjE from Lactococcus lactis IL1403 Is a C-S Lyase with α,γ-Elimination Activity toward Methionine

Martínez-Cuesta

Peláez

Eagles

et al. 2006

Appl Environ Microbiol

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Cheese microbiota and the enzymatic conversion of methionine to volatile sulfur compounds (VSCs) are important factors in flavor formation during cheese ripening and the foci in biotechnological approaches to flavor improvement. The product of ytjE of Lactococcus lactis IL1403, suggested to be a methionine-specific aminotransferase based on genome sequence analysis, was therefore investigated for its role in methionine catabolism. The ytjE gene from Lactococcus lactis IL1403 was cloned in Escherichia coli and overexpressed and purified as a recombinant protein. When tested, the YtjE protein did not exhibit a specific methionine aminotransferase activity. Instead, YtjE exhibited C-S lyase activity and shared homology with the MalY/PatC family of enzymes involved in the degradation of L-cysteine, L-cystine, and L-cystathionine. YtjE was also shown to exhibit ␣,␥-elimination activity toward L-methionine. In addition, gas chromatographic-mass spectrometry analysis showed that YtjE activity resulted in the formation of H 2 S from L-cysteine and methanethiol (and its oxidized derivatives dimethyl disulfide and dimethyl trisulfide) from L-methionine. Given their significance in cheese flavor development, VSC production by YtjE could offer an additional approach for the development of cultures with optimized aromatic properties.

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Identification and characterization of a cystathionine β/γ-lyase from Lactococcus lactis ssp. cremoris MG1363

Abstract: This paper describes the nucleotide sequence of a gene encoding cystathionine L/Q-lyase from Lactococcus lactis ssp. cremoris MG1363, its overexpression in Escherichia coli and some functional characteristics of the purified recombinant protein. ß

Cited by 17 publications

References 27 publications

Cloning and Characterization of Two Lactobacillus casei Genes Encoding a Cystathionine Lyase

Cloning and Characterization of Two Lactobacillus casei Genes Encoding a Cystathionine Lyase

Contribution of several cheese-ripening microbial associations to aroma compound production

YtjE from Lactococcus lactis IL1403 Is a C-S Lyase with α,γ-Elimination Activity toward Methionine

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