Overall control of nitrogen metabolism in Lactococcus lactis by CodY, and possible models for CodY regulation in Firmicutes

Guédon, Éric; Sperandio, Brice; Pons, Nicolas; Ehrlich, S. Dusko; Renault, Pierre

doi:10.1099/mic.0.28186-0

Cited by 127 publications

(173 citation statements)

References 52 publications

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“…Also, spxB (yneH) was reported to be part of the CodY regulon because it has a CodY DNA-binding box in its promoter region (30 bp upstream from the CesR box) (Fig. 9) and was shown to be induced in a codY mutant (31), further suggesting that mtlA and pepN may be important in the context of other stress situations.…”

Section: Discussionmentioning

confidence: 99%

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SpxB Regulates O-Acetylation-dependent Resistance of Lactococcus lactis Peptidoglycan to Hydrolysis

Veiga

Bulbarela-Sampieri

Furlan

et al. 2007

Journal of Biological Chemistry

105

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Endogenous peptidoglycan (PG)-hydrolyzing enzymes, the autolysins, are needed to relax the rigid PG sacculus to allow bacterial cell growth and separation. PGs of pathogens and commensal bacteria may also be degraded by hydrolases of animal origin (lysozymes), which act as antimicrobials. The genetic mechanisms regulating PG resistance to hydrolytic degradation were dissected in the Gram-positive bacterium Lactococcus lactis. We found that the ability of L. lactis to counteract PG hydrolysis depends on the degree of acetylation. Overexpression of PG O-acetylase (encoded by oatA) led to bacterial growth arrest, indicating the potential lethality of oatA and a need for its tight regulation. A novel regulatory factor, SpxB (previously denoted as YneH), exerted a positive effect on oatA expression. Our results indicate that SpxB binding to RNA polymerase constitutes a previously missing link in the multistep response to cell envelope stress, provoked by PG hydrolysis with lysozyme. We suggest that the two-component system CesSR responds to this stress by inducing SpxB, thus favoring its interactions with RNA polymerase. Induction of PG O-acetylation by this cascade renders it resistant to hydrolysis. Peptidoglycan (PG)7 is the major and essential component of the bacterial cell envelope, the main function of which is to preserve cell integrity by withstanding internal osmotic pressure (1, 2). It is also responsible for cell shape, participates in cell division, and serves as support for attachment of other cell wall molecules such as teichoic acids, proteins, and exopolysaccharides (3). The bacterial PG is a giant multilayer polymer that envelops the cell as a rigid sacculus. It is composed of N-acetylglucosamine-N-acetylmuramic acid disaccharide pentapeptide blocks that are synthesized intracellularly and transported through the cytoplasmic membrane as lipid-disaccharide pentapeptides. These blocks are covalently linked to the pre-existing PG polymers by high molecular weight penicillin-binding proteins (4).To allow cell division and surface expansion, the rigid PG sacculus has to be relaxed. This is achieved by PG ruptures, which could be introduced in several ways. First, not all possible covalent bonds are formed during PG synthesis; for example, only 36% of possible PG cross-links between stem peptides are formed in Lactococcus lactis (5). Bacteria also possess a number of endogenous bacterial enzymes (collectively called autolysins) that disrupt PG and can result in cell lysis. According to their hydrolytic bond specificity and products, autolysins are classified as muramidases, lytic transglycosylases, glucosaminidases, amidases, and peptidases (6). Bacteria often possess several autolysins, e.g. L. lactis encodes a main autolysin (N-acetylglucosaminidase AcmA) (7, 8) and four minor PG hydrolases (9, 10) as well as prophage-encoded bacteriolytic enzymes (11).In the human or animal host, antimicrobial PG lytic enzymes such as lysozyme constitute a first line of defense against infection. Bactericidal propertie...

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Section: Discussionmentioning

confidence: 99%

“…Quantitative Real-time (QRT) PCR-RNA extraction and the QRT-PCR approach were carried out using first-strand cDNA as template, which was synthesized from 20-g RNA samples as described (31). The tuf gene (coding for elongation factor TU) was used as internal control and for normalization of results.…”

Section: Methodsmentioning

confidence: 99%

SpxB Regulates O-Acetylation-dependent Resistance of Lactococcus lactis Peptidoglycan to Hydrolysis

Veiga

Bulbarela-Sampieri

Furlan

et al. 2007

Journal of Biological Chemistry

105

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“…The regulation of nitrogen metabolism occurs mainly via GlnR and CodY (196,197). A gene for GlnR is present in all sequenced genomes of LAB, while CodY is present only in strains belonging to the Lactococcus, Streptococcus, and Enterococcus genera.…”

Section: Metabolism Of Nitrogenmentioning

confidence: 99%

Stress Physiology of Lactic Acid Bacteria

Papadimitriou

Alegría

Bron

et al. 2016

Microbiol Mol Biol Rev

515

404

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SUMMARYLactic acid bacteria (LAB) are important starter, commensal, or pathogenic microorganisms. The stress physiology of LAB has been studied in depth for over 2 decades, fueled mostly by the technological implications of LAB robustness in the food industry. Survival of probiotic LAB in the host and the potential relatedness of LAB virulence to their stress resilience have intensified interest in the field. Thus, a wealth of information concerning stress responses exists today for strains as diverse as starter (e.g.,Lactococcus lactis), probiotic (e.g., severalLactobacillusspp.), and pathogenic (e.g.,EnterococcusandStreptococcusspp.) LAB. Here we present the state of the art for LAB stress behavior. We describe the multitude of stresses that LAB are confronted with, and we present the experimental context used to study the stress responses of LAB, focusing on adaptation, habituation, and cross-protection as well as on self-induced multistress resistance in stationary phase, biofilms, and dormancy. We also consider stress responses at the population and single-cell levels. Subsequently, we concentrate on the stress defense mechanisms that have been reported to date, grouping them according to their direct participation in preserving cell energy, defending macromolecules, and protecting the cell envelope. Stress-induced responses of probiotic LAB and commensal/pathogenic LAB are highlighted separately due to the complexity of the peculiar multistress conditions to which these bacteria are subjected in their hosts. Induction of prophages under environmental stresses is then discussed. Finally, we present systems-based strategies to characterize the “stressome” of LAB and to engineer new food-related and probiotic LAB with improved stress tolerance.

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“…6; Table 1). The reduced expression level of this locus in strain KF147_PRT is most probably a consequence of the protease-mediated supply of peptides and free amino acids in that culture (Guedon et al 2005).…”

Section: Transcriptome Of Two Adapted Strains Converges Toward That Omentioning

confidence: 99%

Microbial domestication signatures of Lactococcus lactis can be reproduced by experimental evolution

Bachmann¹,

Starrenburg²,

Molenaar³

et al. 2011

Genome Res.

149

121

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Experimental evolution is a powerful approach to unravel how selective forces shape microbial genotypes and phenotypes. To this date, the available examples focus on the adaptation to conditions specific to the laboratory. The lactic acid bacterium Lactococcus lactis naturally occurs on plants and in dairy environments, and it is proposed that dairy strains originate from the plant niche. Here we investigate the adaptation of a L. lactis strain isolated from a plant to a dairy niche by propagating it for 1000 generations in milk. Two out of three independently evolved strains displayed significantly increased acidification rates and biomass yields in milk. Genome resequencing, revealed six, seven, and 28 mutations in the three strains, including point mutations in loci related to amino acid biosynthesis and transport and in the gene encoding MutL, which is involved in DNA mismatch repair. Two strains lost a conjugative transposon containing genes important in the plant niche but dispensable in milk. A plasmid carrying an extracellular protease was introduced by transformation. Although improving growth rate and growth yield significantly, the plasmid was rapidly lost. Comparative transcriptome and phenotypic analyses confirmed that major physiological changes associated with improved growth in milk relate to nitrogen metabolism and the loss or down-regulation of several pathways involved in the utilization of complex plant polymers. Reproducing the transition from the plant to the dairy niche through experimental evolution revealed several genome, transcriptome, and phenotype signatures that resemble those seen in strains isolated from either niche.

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Overall control of nitrogen metabolism in Lactococcus lactis by CodY, and possible models for CodY regulation in Firmicutes

Cited by 127 publications

References 52 publications

SpxB Regulates O-Acetylation-dependent Resistance of Lactococcus lactis Peptidoglycan to Hydrolysis

SpxB Regulates O-Acetylation-dependent Resistance of Lactococcus lactis Peptidoglycan to Hydrolysis

Stress Physiology of Lactic Acid Bacteria

Microbial domestication signatures of Lactococcus lactis can be reproduced by experimental evolution

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