Gene inactivation in Lactococcus lactis: branched-chain amino acid biosynthesis

Godon, Jean‐Jacques; Delorme, Christine; Bardowski, Jacek; Chopin, Marie-Christine; Ehrlich, S. Dusko; Renault, Pierre

doi:10.1128/jb.175.14.4383-4390.1993

Cited by 107 publications

(84 citation statements)

References 41 publications

(36 reference statements)

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“…Thus, although L. lactis MG1363 like many other lactococcal dairy strains is auxotrophic for these amino acids, several genes of the BCAA biosynthetic operon are present on the chromosome and are actively transcribed (1,53). The gene encoding the aminotransferase BcaT, catalyzing either the first step of aromatic or branched-chain amino acid catabolism or the last step of their biosynthesis (54,55), was also significantly derepressed.…”

Section: Role Of Cody In Global Genementioning

confidence: 93%

“…For the Gram-positive organism Lactococcus lactis, a lactic acid bacterium, auxotrophic for branched-chain amino acids (BCAAs), 2 methionine and histidine (1)(2)(3), maintenance of the nitrogen balance is essential. When this bacterium grows in milk, it uses the ubiquitous milk proteins (caseins) for its growth, employing a comprehensive and balanced proteolytic system (4 -6).…”

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confidence: 99%

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The Lactococcus lactis CodY Regulon

Hengst

Hijum

Geurts

et al. 2005

Journal of Biological Chemistry

178

106

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CodY of Lactococcus lactis MG1363 is a transcriptional regulator that represses the expression of several genes encoding proteins of the proteolytic system. DNA microarray analysis, comparing the expression profiles of L. lactis MG1363 and an isogenic strain in which codY was mutated, was used to determine the CodY regulon. In peptide-rich medium and exponentially growing cells, where CodY exerts strong repressing activity, the expression of over 30 genes was significantly increased upon removal of codY. The differentially expressed genes included those predominantly involved in amino acid transport and metabolism. In addition, several genes belonging to other functional categories were derepressed, stressing the pleiotropic role of CodY. Scrutinizing the transcriptome data with bioinformatics tools revealed the presence of a novel overrepresented motif in the upstream regions of several of the genes derepressed in L. lactis MG1363⌬codY. Evidence is presented that this 15-bp cis-sequence, AATTTTCWGAAAATT, serves as a high affinity binding site for CodY, as shown by electrophoretic mobility shift assays and DNase I footprinting analyses. The presence of this CodY-box is sufficient to evoke CodY-mediated regulation in vivo. A copy of this motif is also present in the upstream region of codY itself. It is shown that CodY regulates its own synthesis and requires the CodY-box and branched-chain amino acids to interact with its promoter.For the Gram-positive organism Lactococcus lactis, a lactic acid bacterium, auxotrophic for branched-chain amino acids (BCAAs), 2 methionine and histidine (1-3), maintenance of the nitrogen balance is essential. When this bacterium grows in milk, it uses the ubiquitous milk proteins (caseins) for its growth, employing a comprehensive and balanced proteolytic system (4 -6). The extracellular cell wall-bound serine proteinase (PrtP) is an essential part of the proteolytic system, as it hydrolyzes the large caseins into smaller fragments. These peptides of various sizes, and free amino acids, can then be taken up into the cell by various transport systems, e.g. the oligopeptide transport system Opp (4) and the di-and tripeptide transport systems DtpP and DtpT (7,8). Once inside, the peptides are degraded further by either endopeptidases (e.g. PepO and PepF) or aminopeptidases (e.g. PepN, PepX, and PepC) (9).Although the proteolytic system of lactic acid bacteria has been characterized thoroughly over the past 20 years (6), new components are still being identified. For example, upon deletion of the main transport system for oligopeptides (opp), growth on media containing specific oligopeptides was still possible (10), suggesting the presence of at least one additional peptide transport system. Recently, a novel peptide transporter has been identified, encoded by dpp (opt), which is able to take over (part of) the role of opp (10 -12).Previous studies have shown that expression in L. lactis MG1363 of a number of genes of the proteolytic system is repressed in nitrogen-rich media. When L. l...

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Section: Role Of Cody In Global Genementioning

confidence: 93%

mentioning

confidence: 99%

The Lactococcus lactis CodY Regulon

Hengst

Hijum

Geurts

et al. 2005

Journal of Biological Chemistry

178

106

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“…In Lactococcus spp., leucine biosynthesis is encoded by the ILV and LEU operon (Godon et al 1992(Godon et al , 1993. The last step in the leucine anabolism and first step Leucine catabolism are the same: the conversion between a-keto-isocaproic acid and leucine by a transaminase (Godon et al 1992).…”

Section: Amino Acid Pool (Reactions 1 and 2)mentioning

confidence: 99%

Branched chain aldehydes: production and breakdown pathways and relevance for flavour in foods

Smit¹,

Engels

Smit

2009

Appl Microbiol Biotechnol

239

173

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Branched aldehydes, such as 2-methyl propanal and 2-and 3-methyl butanal, are important flavour compounds in many food products, both fermented and non-fermented (heat-treated) products. The production and degradation of these aldehydes from amino acids is described and reviewed extensively in literature. This paper reviews aspects influencing the formation of these aldehydes at the level of metabolic conversions, microbial and food composition. Special emphasis was on 3-methyl butanal and its presence in various food products. Knowledge gained about the generation pathways of these flavour compounds is essential for being able to control the formation of desired levels of these aldehydes.

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“…La protéolyse: la nutrition azotée, le recyclage des protéines et l'affinage Une deuxième particularité de nombreuses bactéries lactiques est leur incapacité à produire certains acides aminés dont elles ont besoin [9,16]. De plus, même si elles sont capables de les synthétiser un à un, elles ont une croissance très ralentie dès qu'elles doivent en fabriquer plusieurs.…”

Section: La Redirection Des Flux Carbonésunclassified

Du génome à l'application

Renault

Calero

Delorme

et al. 1998

Lait

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-From genome to industrial application. The possibility to use modified microorganisms constructed by genetic engineering for food production in the next future will radically change our approach to optimize processes and improve the quality of the corresponding products. The research holding on this domain should allow the construction of strains more resistant to phage attack, producing new molecules (e.g. beneficial for health) or modified for their metabolism (growth, production of metabolites, resistance to stress, etc). The construction of such strains can be achieved by genetic engineering, either by modifying a pathway, or by expressing new genes. The engineering of known pathways allowed the development of new process and sorne of them are technically ready to be applied in the industry. For example, the expression of the anabolic acetolactate synthase, the inactivation of the LDH or of the acetolactate decarboxylase lead to the redirection of pyruvate to diacetyl instead of lactate. This might lead to a JO-fold increase in diacetyl production, and there are still sorne possibilities of improvement. Another project of metabolic engineering that is quite advanced, is the modification of proteolysis in Lactococcus lactis, including the degradation of casein, peptides and amino acids. Most genes involved in the assimilation of proteins have been characterized (cell-wall protease, peptides transporters, and peptidases). Isogenic strains with different level of peptidase activities are built in order to improve peptidolysis or change the pattern of its product. In addition to the modification of already existing pathways, the introduction of new pathways in a cell could brighten the metabolic possibilities of bacteria and lead to the construction of new strains, producing new aroma for example. Building a new pathway generally requires the expression of heterologous genes. However, the certitude that a gene is absent supposes that there is an exhaustive knowledge of the bacterial genome, as sorne genes may be cryptic or uninduced under the conditions tested in the laboratory. Although the important progresses in the research related to lactic acid bacteria in the last years, only few pathways have been weil characterized, covering, in terms of genetic information, a small percentage of the real metabolic possibilities. The size of the chromosome of most lactic acid bacteria is usually 1.8-3.4 Mb, about the half of the one of Escherichia coli, Bacillus subtilis and of sorne soil bacteria which have broad metabolic possibilities. On the other side, it is 4-5 fold the size of the smallest known genome, suggesting that the metabolic potentialities of lactic acid bacteria are underestimated. An investigation of data present in databases * Correspondance et tirés à part. shows that only 6% of the genome of L. lactis are available. These data co ver genes involved in amino acids and base biosynthesis (33%), degradation of peptides (17%), carbon catabolism (16%), stress responses (13%) and the remaining gen...

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Gene inactivation in Lactococcus lactis: branched-chain amino acid biosynthesis

Cited by 107 publications

References 41 publications

The Lactococcus lactis CodY Regulon

The Lactococcus lactis CodY Regulon

Branched chain aldehydes: production and breakdown pathways and relevance for flavour in foods

Du génome à l'application

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