Comparison of ?-acetolactate synthase and ?-acetolactate decarboxylase in Lactococcus spp. and Leuconostoc spp.

Monnet, Christophe; Phalip, Vincent; Schmitt, Philippe; Diviès, Charles

doi:10.1007/bf00134622

Cited by 36 publications

(31 citation statements)

References 18 publications

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“…Similarly, separate addition of 1^10 mM branched chain amino acids (leucine, valine and isoleucine) also had no e¡ect on ALD activity. This result di¡ers from that obtained for L. lactis where a 14^40-fold increase in activity was observed in the presence of these amino acids [2].…”

Section: Enzyme Characterisationcontrasting

confidence: 55%

“…The current consensus is that diacetyl biosynthesis arises from spontaneous oxidative decarboxylation of ALA [2] and 13 C NMR has demonstrated that ALA is a direct precursor of both acetoin and diacetyl and that acetoin does not give rise to diacetyl [3]. Previous studies have suggested that diacetyl production may be enzyme-mediated by a putative diacetyl synthase catalysing the condensation of active acetaldehyde (hydroxyethyl-thiamine pyrophosphate (TPP)) with acetyl CoA [4], although such an enzyme has never been found in lactic acid bacteria despite exhaustive research [3,5].…”

Section: Introductionmentioning

confidence: 99%

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Purification and characterisation of acetolactate decarboxylase from Leuconostoc lactis NCW1

O'Sullivan

2001

FEMS Microbiology Letters

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A two-step strategy involving DEAE-cellulose and POROS PI anion exchange chromatography has been developed for rapid purification of acetolactate decarboxylase (ALD) from Leuconostoc lactis NCW1. This results in 5333-fold purification with a yield of 30%. Purified ALD is a dimer of 49-kDa subunits, has a pH optimum of 6.0, a pI of 4.2 and its activity is independent of metals or branched chain amino acids. At the optimum pH, the K m for 2-acetolactate (ALA) was found to be 1.3 mM and the turnover number was 4000 min 31 . N-terminal sequence comparison with other ALDs showed little sequence conservation in this region. Purified ALD does not catalyse direct production of diacetyl from ALA, unlike the crude extract. ß

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Section: Enzyme Characterisationcontrasting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Purification and characterisation of acetolactate decarboxylase from Leuconostoc lactis NCW1

O'Sullivan

2001

FEMS Microbiology Letters

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“…The pfl transcription start site is indicated with an arrow beside the sequence line. (21,22,35; also, see the introduction). Additionally, an L. lactis ldh strain lacking LDH would be expected to direct the pyruvate pools towards ␣-acetolactate via ALS and yield a higher amount of diacetyl (Fig.…”

Section: Discussionmentioning

confidence: 97%

Cloning, expression, and characterization of the Lactococcus lactis pfl gene, encoding pyruvate formate-lyase

Arnau¹,

Jørgensen²,

Madsen³

et al. 1997

J Bacteriol

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The Lactococcus lactis pfl gene, encoding pyruvate formate-lyase (PFL), has been cloned and characterized. The deduced amino acid sequence of the L. lactis PFL protein showed high similarity to those of other bacterial PFL proteins and included the conserved glycine residue involved in posttranslational activation of PFL. The genetic organization of the chromosomal pfl region in L. lactis showed differences from other characterized pfl loci, with an upstream open reading frame independently transcribed in the same orientation as the pfl gene. The gene coding for PFL-activase (act), normally found downstream of pfl, was not identified in L. lactis. Analysis of pfl expression showed a strong induction under anaerobiosis at the transcriptional level independent of the growth medium used. During growth with galactose, pfl showed the highest levels of expression. Constructed L. lactis pfl strains were unable to produce formate under anaerobic growth. Higher levels of diacetyl and acetoin were produced anaerobically in the constructed Lactococcus lactis subsp. lactis biovar diacetylactis pfl strain.Pyruvate has a key role in the metabolic network of Lactococcus lactis. In this industrially relevant organism, sugars are metabolized predominantly to generate energy and as a carbon source. The catabolism of sugars leads to pyruvate, whose further metabolism determines the nature of the fermentation (see reference 5 for a review). Lactate is the major end product responsible for acidification, while other minor metabolites, mainly diacetyl, are responsible for aroma in fermented milk products. Several genes involved in pyruvate metabolism have been studied for their role in the production of diacetyl (Fig.

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“…AL and the total amount of diacetyl plus acetoin were assayed as previously reported (39,59,61). Lactose, glucose, lactate, acetate, formate, ethanol, pyruvate, and butanediol production was determined by high-performance liquid chromatography with an HPX-78P anionexchange column (Bio-Rad Laboratories, Inc.) with 5 mM H 2 SO 4 as the eluent at 48°C.…”

Section: Methodsmentioning

confidence: 99%

Dual role of alpha-acetolactate decarboxylase in Lactococcus lactis subsp. lactis

et al. 1997

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The ␣-acetolactate decarboxylase gene aldB is clustered with the genes for the branched-chain amino acids (BCAA) in Lactococcus lactis subsp. lactis. It can be transcribed with BCAA genes under isoleucine regulation or independently of BCAA synthesis under the control of its own promoter. The product of aldB is responsible for leucine sensibility under valine starvation. In the presence of more than 10 M leucine, the ␣-acetolactate produced by the biosynthetic acetohydroxy acid synthase IlvBN is transformed to acetoin by AldB and, consequently, is not available for valine synthesis. AldB is also involved in acetoin formation in the 2,3-butanediol pathway, initiated by the catabolic acetolactate synthase, AlsS. The differences in the genetic organization, the expression, and the kinetics parameters of these enzymes between L. lactis and Klebsiella terrigena, Bacillus subtilis, or Leuconostoc oenos suggest that this pathway plays a different role in the metabolism in these bacteria. Thus, the ␣-acetolactate decarboxylase from L. lactis plays a dual role in the cell: (i) as key regulator of valine and leucine biosynthesis, by controlling the acetolactate flux by a shift to catabolism; and (ii) as an enzyme catalyzing the second step of the 2,3-butanediol pathway.Synthesis of the three branched-chain amino acids (BCAA), leucine, isoleucine, and valine, has been studied in detail in organisms as diverse as bacteria, fungi, and plants (for reviews, see references 8, 32, 57, and 58). A particular feature of this synthesis is that it is carried out, in part, by the same enzymes for the three amino acids (Fig. 1). However, the relative amounts of the three amino acids in cell proteins are not the same, since leucine, valine, and isoleucine represent 39, 36, and 25%, respectively, of the total BCAA in Escherichia coli (40). Regulation of the BCAA synthesis is therefore necessarily complex. A global regulation model has been established only for E. coli (58). Two levels of regulation, concerning gene transcription and enzyme inhibition, have previously been described.E. coli genes which encode BCAA synthesis enzymes form three clusters and are organized in five transcription units (2). Initiation of transcription of all the genes except ilvC is regulated by nonspecific, pleiotropic regulators responding to amino acid starvation and different changes in the medium (58). In addition to this control, a mechanism of transcriptional attenuation dependent on the synthesis of a leader peptide as described first for the tryptophan operon (33) negatively regulates ilvBN, ilvGMEDA, and leuABCD. These mechanisms allow the expression of the enzymes necessary for BCAA synthesis when needed.Activity of several BCAA-synthesizing enzymes is regulated by retroinhibition (Fig. 1). This control is simple in the case of leucine and isoleucine, since each amino acid inhibits an enzyme specific for an early step of its synthesis (LeuA and IlvA, respectively [53,57]). In contrast, the first enzyme involved in valine synthesis is also required fo...

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Comparison of ?-acetolactate synthase and ?-acetolactate decarboxylase in Lactococcus spp. and Leuconostoc spp.

Cited by 36 publications

References 18 publications

Purification and characterisation of acetolactate decarboxylase from Leuconostoc lactis NCW1

Purification and characterisation of acetolactate decarboxylase from Leuconostoc lactis NCW1

Cloning, expression, and characterization of the Lactococcus lactis pfl gene, encoding pyruvate formate-lyase

Dual role of alpha-acetolactate decarboxylase in Lactococcus lactis subsp. lactis

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