Proteomic analysis of <b><i>Lactococcus lactis</i></b>, a lactic acid bacterium

Guillot, Alain; Gitton, Christophe; Anglade, Patricia; Mistou, Michel‐Yves

doi:10.1002/pmic.200390047

Cited by 113 publications

(133 citation statements)

References 49 publications

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“…Although many LTTRs negatively control their own transcription, FhuR might be among exceptions to this general rule. Possibly, the lack of retrocontrol of fhuR gene transcription is correlated to high abundance of its product in the cell, clearly identifiable by two-dimensional gel electrophoresis (33).…”

Section: Discussionmentioning

confidence: 99%

Sulfur Amino Acid Metabolism and Its Control in Lactococcus lactis IL1403

et al. 2005

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Cysteine and methionine availability influences many processes in the cell. In bacteria, transcription of the specific genes involved in the synthesis of these two amino acids is usually regulated by different mechanisms or regulators. Pathways for the synthesis of cysteine and methionine and their interconversion were experimentally determined for Lactococcus lactis, a lactic acid bacterium commonly found in food. A new gene, yhcE, was shown to be involved in methionine recycling to cysteine. Surprisingly, 18 genes, representing almost all genes of these pathways, are under the control of a LysR-type activator, FhuR, also named CmbR. DNA microarray experiments showed that FhuR targets are restricted to this set of 18 genes clustered in seven transcriptional units, while cysteine starvation modifies the transcription level of several other genes potentially involved in oxidoreduction processes. Purified FhuR binds a 13-bp box centered 46 to 53 bp upstream of the transcriptional starts from the seven regulated promoters, while a second box with the same consensus is present upstream of the first binding box, separated by 8 to 10 bp. O-Acetyl serine increases FhuR binding affinity to its binding boxes. The overall view of sulfur amino acid metabolism and its regulation in L. lactis indicates that CysE could be a master enzyme controlling the activity of FhuR by providing its effector, while other controls at the enzymatic level appear to be necessary to compensate the absence of differential regulation of the genes involved in the interconversion of methionine and cysteine and other biosynthesis genes.Sulfur is a constituent of many indispensable components of the cell, such as cysteine, methionine, thiamine, biotin, lipoic acid, coenzyme A, etc. Among these compounds, cysteine has a central role, since its de novo synthesis represents the main pathway of sulfur acquisition in microorganisms and plants. Cysteine is thus the principal metabolite from which most sulfur-containing compounds are built. It is also an essential amino acid of the catalytic domain of universal proteins having iron-sulfur clusters, such as cytochromes and aconitase. Cysteine also plays a central role in protein folding, assembly, and stability via the formation of disulfide bounds. Moreover, cysteine-derived proteins, such as thioredoxin and glutathione, play a central role in the protection against oxidative stress. The second sulfur amino acid, methionine, is a key compound controlling the initiation of translation and is crucial to a variety of methyltransferase reactions.As a result of the essential roles in metabolism, cysteine and methionine supply might be limiting for bacterial growth in different situations of importance for humans, such as pathogenic events or fermentation processes. For example, methionine availability is limiting for growth of group B streptococci in plasma (65). Sulfur amino acid biosynthesis genes have been characterized as virulence factors in Brucella melitensis (48), Haemophilus parasuis (36), and Salmonel...

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Section: Discussionmentioning

confidence: 99%

Sulfur Amino Acid Metabolism and Its Control in Lactococcus lactis IL1403

et al. 2005

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“…This technique has been used successfully to visualize variations of protein levels as well as posttranslational modifications (21). Our studies reveal that, compared to fermentation, respiration affects the level as well as the posttranslational processing of certain proteins.…”

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confidence: 93%

Proteome Analyses of Heme-Dependent Respiration inLactococcus lactis: Involvement of the Proteolytic System

Vido

Bars²,

Mistou³

et al. 2004

J Bacteriol

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Sugar fermentation was long considered the sole means of energy metabolism available to lactic acid bacteria. We recently showed that metabolism of Lactococcus lactis shifts progressively from fermentation to respiration during growth when oxygen and heme are available. To provide insights into this phenomenon, we compared the proteomic profiles of L. lactis under fermentative and respiratory growth conditions in rich medium. We identified 21 proteins whose levels differed significantly between these conditions. Two major groups of proteins were distinguished, one involved in carbon metabolism and the second in nitrogen metabolism. Unexpectedly, enzymes of the proteolytic system (PepO1 and PepC) which are repressed in rich medium in fermentation growth were induced under respiratory conditions despite the availability of free amino acids. A triple mutant (dtpT dtpP oppA) deficient in oligopeptide transport displayed normal respiration, showing that increased proteolytic activity is not an absolute requirement for respiratory metabolism. Transcriptional analysis confirmed that pepO1 is induced under respiration-permissive conditions. This induction was independent of CodY, the major regulator of proteolytic functions in L. lactis. We also observed that pepO1 induction is redox sensitive. In a codY mutant, pepO1 expression was increased twofold in aeration and eightfold in respiration-permissive conditions compared to static conditions. These observations suggest that new regulators activate proteolysis in L. lactis, which help to maintain the energetic needs of L. lactis during respiration.

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“…Individual spots were excised from gels and submitted to tryptic digestion, and mass spectrometry analyses were performed as previously described (19). MS-Fit (University of California San Francisco Mass Spectrometry Facility; http://prospector.ucsf.edu) and Mascot (Matrix Science Inc., Boston, MA; http://www.matrixscience.com /search_form_select.html), installed locally, were used to identify proteins from peptide mass fingerprints.…”

Section: Methodsmentioning

confidence: 99%

Proteomic Analysis of Global Changes in Protein Expression during Bile Salt Exposure of Bifidobacterium longum NCIMB 8809

Sánchez

Champomier‐Vergès²,

Anglade³

et al. 2005

J Bacteriol

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Adaptation to and tolerance of bile stress are among the main limiting factors to ensure survival of bifidobacteria in the intestinal environment of humans. The effect of bile salts on protein expression patterns of Bifidobacterium longum was examined. Protein pattern comparison of strains grown with or without bile extract allowed us to identify 34 different proteins whose expression was regulated. The majority of these proteins were induced after both a minor (0.6 g liter ؊1 ) and a major (1.2 g liter ؊1 ) exposure to bile. These include general stress response chaperones, proteins involved in transcription and translation and in the metabolism of amino acids and nucleotides, and several enzymes of glycolysis and pyruvate catabolism. Remarkably, xylulose 5-phosphate/fructose 6-phosphate phosphoketolase, the key enzyme of the so-called bifidobacterial shunt, was found to be upregulated, and the activity on fructose 6-phosphate was significantly higher for protein extracts of cells grown in the presence of bile. Changes in the levels of metabolic end products (acetate and lactate) were also detected. These results suggest that bile salts, to which bifidobacteria are naturally exposed, induce a complex physiological response rather than a single event in which proteins from many different functional categories take part. This study has extended our understanding of the molecular mechanism underlying the capacity of intestinal bifidobacteria to tolerate bile.

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Proteomic analysis of Lactococcus lactis, a lactic acid bacterium

Cited by 113 publications

References 49 publications

Sulfur Amino Acid Metabolism and Its Control in Lactococcus lactis IL1403

Sulfur Amino Acid Metabolism and Its Control in Lactococcus lactis IL1403

Proteome Analyses of Heme-Dependent Respiration inLactococcus lactis: Involvement of the Proteolytic System

Proteomic Analysis of Global Changes in Protein Expression during Bile Salt Exposure of Bifidobacterium longum NCIMB 8809

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