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Didier Lereclus - One of the best experts on this subject based on the ideXlab platform.

  • The Signaling Peptide PapR is required for the activity of the quorum-sensor PlcRa in Bacillus thuringiensis
    Microbiology, 2020
    Co-Authors: Eugenie Huillet, Ludovic Bridoux, Isabelle Barboza, Christelle Lemy, Gwénaëlle André-leroux, Didier Lereclus
    Abstract:

    The transcriptional regulator PlcR, its cognate cell-cell Signaling heptaPeptide PapR7 , and the oligoPeptide permease OppABCDF, required for PapR7 import, form a quorum-sensing system that controls the expression of virulence factors in Bacillus cereus and Bacillus thuringiensis species. In B. cereus strain ATCC 14579, the transcriptional regulator PlcRa activates the expression of abrB2 gene, which encodes an AbrB-like transcriptional regulator involved in cysteine biosynthesis. PlcRa is a structural homolog of PlcR: in particular, its C-terminal TPR Peptide-binding domain could be similarly arranged as in PlcR. The Signaling Peptide of PlcRa is not known. As PlcRa is a PlcR-like protein, the cognate PapR7 Peptide (ADLPFEF) is a relevant candidate to act as a Signaling Peptide for PlcRa activation. Also, the putative PapRa7 Peptide (CSIPYEY), encoded by the papRa gene adjacent to the plcRa gene, is a relevant candidate as addition of synthetic PapRa7 induces a dose-dependent increase of abrB2 expression. To address the issue of Peptide selectivity of PlcRa, the role of PapR and PapRa Peptides in PlcRa activity was investigated in B. thuringiensis 407 strain, by genetic and functional complementation analyses. A transcriptional fusion between the promoter of abrB2 and lacZ was used to monitor the PlcRa activity in various genetic backgrounds. We demonstrated that PapR was necessary and sufficient for PlcRa activity. We showed that synthetic PapRs from pherogroups II, III and IV and synthetic PapRa7 were able to trigger abrB2 expression, suggesting that PlcRa is less selective than PlcR. Lastly, the mode of binding of PlcRa was addressed using an in silico approach. Overall, we report a new role for PapR as a Signaling Peptide for PlcRa activity and show a functional link between PlcR and PlcRa regulons in B. thuringiensis.

  • The Signaling Peptide NprX controlling sporulation and necrotrophism is imported into Bacillus thuringiensis by two oligoPeptide permease systems
    Molecular Microbiology, 2019
    Co-Authors: Thomas Dubois, Christelle Lemy, Stephane Perchat, Didier Lereclus
    Abstract:

    The infectious cycle of Bacillus thuringiensis in the insect host is regulated by quorum sensors of the RNPP family. The activity of these regulators is modulated by their cognate Signaling Peptides translocated into the bacterial cells by oligoPeptide permeases (Opp systems). In B. thuringiensis, the quorum sensor NprR is a bi-functional regulator that connects sporulation to necrotrophism. The binding of the Signaling Peptide NprX switches NprR from a dimeric inhibitor of sporulation to a tetrameric transcriptional activator involved in the necrotrophic lifestyle of B. thuringiensis. Here, we report that NprX is imported into the bacterial cells by two different oligoPeptide permease systems. The first one is Opp, the system known to be involved in the import of the Signaling Peptide PapR in B. thuringiensis and Bacillus cereus. The second, designated as Npp (NprX Peptide permease), was not previously described. We show that at least two substrate binding proteins (SBPs) are able to translocate NprX through OppBCDF. In contrast, we demonstrate that a unique SBP (NppA) can translocate NprX through NppDFBC. We identified the promoter of the npp operon, and we showed that transcription starts at the onset of stationary phase and is repressed by the nutritional regulator CodY during the exponential growth phase.

  • How Quorum Sensing Connects Sporulation to Necrotrophism in Bacillus thuringiensis.
    PLoS Pathogens, 2016
    Co-Authors: Stephane Perchat, Didier Lereclus, Antoine Talagas, Sandrine Poncet, Noureddine Lazar, Inès Li De La Sierra-gallay, Michel Gohar, Sylvie Nessler
    Abstract:

    Bacteria use quorum sensing to coordinate adaptation properties, cell fate or commitment to sporulation. The infectious cycle of Bacillus thuringiensis in the insect host is a powerful model to investigate the role of quorum sensing in natural conditions. It is tuned by communication systems regulators belonging to the RNPP family and directly regulated by re-internalized Signaling Peptides. One such RNPP regulator, NprR, acts in the presence of its cognate Signaling Peptide NprX as a transcription factor, regulating a set of genes involved in the survival of these bacteria in the insect cadaver. Here, we demonstrate that, in the absence of NprX and independently of its transcriptional activator function, NprR negatively controls sporulation. NprR inhibits expression of Spo0A-regulated genes by preventing the KinA-dependent phosphorylation of the phosphotransferase Spo0F, thus delaying initiation of the sporulation process. This NprR function displays striking similarities with the Rap proteins, which also belong to the RNPP family, but are devoid of DNA-binding domain and indirectly control gene expression via protein-protein interactions in Bacilli. Conservation of the Rap residues directly interacting with Spo0F further suggests a common inhibition of the sporulation phosphorelay. The crystal structure of apo NprR confirms that NprR displays a highly flexible Rap-like structure. We propose a molecular regulatory mechanism in which key residues of the bifunctional regulator NprR are directly and alternatively involved in its two functions. NprX binding switches NprR from a dimeric inhibitor of sporulation to a tetrameric transcriptional activator involved in the necrotrophic lifestyle of B. thuringiensis. NprR thus tightly coordinates sporulation and necrotrophism, ensuring survival and dissemination of the bacteria during host infection.

  • CodY regulates the activity of the virulence quorum sensor PlcR by controlling the import of the Signaling Peptide PapR in Bacillus thuringiensis
    Frontiers in Microbiology, 2016
    Co-Authors: Leyla Slamti, Eugenie Huillet, Christelle Lemy, Celine Henry, Alain Guillot, Didier Lereclus
    Abstract:

    In Gram-positive bacteria, cell–cell communication mainly relies on cytoplasmic sensors of the RNPP family. Activity of these regulators depends on their binding to secreted Signaling Peptides that are imported into the cell. These quorum sensing regulators control important biological functions in bacteria of the Bacillus cereus group, such as virulence and necrotrophism. The RNPP quorum sensor PlcR, in complex with its cognate Signaling Peptide PapR, is the main regulator of virulence in B. cereus and Bacillus thuringiensis(Bt). Recent reports have shown that the global stationary phase regulator CodY, involved in adaptation to nutritional limitation, is required for the expression of virulence genes belonging to the PlcR regulon. However, the mechanism underlying this regulation was not described. Using genetics and proteomics approaches, we showed that CodY regulates the expression of the virulence genes through the import of PapR. We report that CodY positively controls the production of the proteins that compose the oligoPeptide permease OppABCDF, and of several other Opp-like proteins. It was previously shown that the pore components of this oligoPeptide permease, OppBCDF, were required for the import of PapR. However, the role of OppA, the substrate-binding protein (SBP), was not investigated. Here, we demonstrated that OppA is not the only SBP involved in the recognition of PapR, and that several other OppA-like proteins can allow the import of this Peptide. Altogether, these data complete our model of quorum sensing during the lifecycle of Bt and indicate that RNPPs integrate environmental conditions, as well as cell density, to coordinate the behavior of the bacteria throughout growth

  • NprR, a moonlighting quorum sensor shifting from a phosphatase activity to a transcriptional activator
    Microbial Cell, 2016
    Co-Authors: Stephane Perchat, Samira Zouhir, Sylvie Nessler, Antoine Talagas, Sandrine Poncet-mouturat, Laurent Bouillaut, Didier Lereclus
    Abstract:

    Regulation of biological functions requires factors (proteins, Peptides or chemicals) able to sense and translate environmental conditions or any circumstances in order to modulate the transcription of a gene, the stability of a transcript or the activity of a protein. Quorum sensing is a regulation mechanism connecting cell density to the physiological state of a single cell. In bacteria, quorum sensing coordinates virulence, cell fate and commitment to sporulation and other adaptation properties. The critical role of such regulatory systems was demonstrated in pathogenicity and adaptation of bacteria from the Bacillus cereus group (i.e. B. cereus and Bacillus thuringiensis). Furthermore, using insects as a model of infection, it was shown that sequential activation of several quorum sensing systems allowed bacteria to switch from a virulence state to a necrotrophic lifestyle, allowing their survival in the host cadaver, and ultimately to the commitment into sporulation. The chronological development of these physiological states is directed by quorum sensors forming the RNPP family. Among them, NprR combines two distinct functions connecting sporulation to necrotrophism in B. thuringiensis. In the absence of its cognate Signaling Peptide (NprX), NprR negatively controls sporulation by acting as a phosphatase. In the presence of NprX, it acts as a transcription factor regulating a set of genes involved in the survival of the bacteria in the insect cadaver.

Sylvie Nessler - One of the best experts on this subject based on the ideXlab platform.

  • How Quorum Sensing Connects Sporulation to Necrotrophism in Bacillus thuringiensis.
    PLoS Pathogens, 2016
    Co-Authors: Stephane Perchat, Didier Lereclus, Antoine Talagas, Sandrine Poncet, Noureddine Lazar, Inès Li De La Sierra-gallay, Michel Gohar, Sylvie Nessler
    Abstract:

    Bacteria use quorum sensing to coordinate adaptation properties, cell fate or commitment to sporulation. The infectious cycle of Bacillus thuringiensis in the insect host is a powerful model to investigate the role of quorum sensing in natural conditions. It is tuned by communication systems regulators belonging to the RNPP family and directly regulated by re-internalized Signaling Peptides. One such RNPP regulator, NprR, acts in the presence of its cognate Signaling Peptide NprX as a transcription factor, regulating a set of genes involved in the survival of these bacteria in the insect cadaver. Here, we demonstrate that, in the absence of NprX and independently of its transcriptional activator function, NprR negatively controls sporulation. NprR inhibits expression of Spo0A-regulated genes by preventing the KinA-dependent phosphorylation of the phosphotransferase Spo0F, thus delaying initiation of the sporulation process. This NprR function displays striking similarities with the Rap proteins, which also belong to the RNPP family, but are devoid of DNA-binding domain and indirectly control gene expression via protein-protein interactions in Bacilli. Conservation of the Rap residues directly interacting with Spo0F further suggests a common inhibition of the sporulation phosphorelay. The crystal structure of apo NprR confirms that NprR displays a highly flexible Rap-like structure. We propose a molecular regulatory mechanism in which key residues of the bifunctional regulator NprR are directly and alternatively involved in its two functions. NprX binding switches NprR from a dimeric inhibitor of sporulation to a tetrameric transcriptional activator involved in the necrotrophic lifestyle of B. thuringiensis. NprR thus tightly coordinates sporulation and necrotrophism, ensuring survival and dissemination of the bacteria during host infection.

  • NprR, a moonlighting quorum sensor shifting from a phosphatase activity to a transcriptional activator
    Microbial Cell, 2016
    Co-Authors: Stephane Perchat, Samira Zouhir, Sylvie Nessler, Antoine Talagas, Sandrine Poncet-mouturat, Laurent Bouillaut, Didier Lereclus
    Abstract:

    Regulation of biological functions requires factors (proteins, Peptides or chemicals) able to sense and translate environmental conditions or any circumstances in order to modulate the transcription of a gene, the stability of a transcript or the activity of a protein. Quorum sensing is a regulation mechanism connecting cell density to the physiological state of a single cell. In bacteria, quorum sensing coordinates virulence, cell fate and commitment to sporulation and other adaptation properties. The critical role of such regulatory systems was demonstrated in pathogenicity and adaptation of bacteria from the Bacillus cereus group (i.e. B. cereus and Bacillus thuringiensis). Furthermore, using insects as a model of infection, it was shown that sequential activation of several quorum sensing systems allowed bacteria to switch from a virulence state to a necrotrophic lifestyle, allowing their survival in the host cadaver, and ultimately to the commitment into sporulation. The chronological development of these physiological states is directed by quorum sensors forming the RNPP family. Among them, NprR combines two distinct functions connecting sporulation to necrotrophism in B. thuringiensis. In the absence of its cognate Signaling Peptide (NprX), NprR negatively controls sporulation by acting as a phosphatase. In the presence of NprX, it acts as a transcription factor regulating a set of genes involved in the survival of the bacteria in the insect cadaver.

  • structural basis for the activation mechanism of the plcr virulence regulator by the quorum sensing signal Peptide papr
    Proceedings of the National Academy of Sciences of the United States of America, 2013
    Co-Authors: Rosa Grenha, Didier Lereclus, Leyla Slamti, Magali Nicaise, Sylvie Nessler, Yacine Refes
    Abstract:

    The quorum-sensing regulator PlcR is the master regulator of most known virulence factors in Bacillus cereus. It is a helix-turn-helix (HTH)-type transcription factor activated upon binding of its cognate Signaling Peptide PapR on a tetratricoPeptide repeat-type regulatory domain. The structural and functional properties of PlcR have defined a new family of sensor regulators, called the RNPP family (for Rap, NprR, PrgX, and PlcR), in Gram-positive bacteria. To fully understand the activation mechanism of PlcR, we took a closer look at the conformation changes induced upon binding of PapR and of its target DNA, known as PlcR-box. For that purpose we have determined the structures of the apoform of PlcR (Apo PlcR) and of the ternary complex of PlcR with PapR and the PlcR-box from the plcA promoter. Comparison of the apoform of PlcR with the previously published structure of the PlcR–PapR binary complex shows how a small conformational change induced in the C-terminal region of the tetratricoPeptide repeat (TPR) domain upon Peptide binding propagates via the linker helix to the N-terminal HTH DNA-binding domain. Further comparison with the PlcR–PapR–DNA ternary complex shows how the activation of the PlcR dimer allows the linker helix to undergo a drastic conformational change and subsequent proper positioning of the HTH domains in the major groove of the two half sites of the pseudopalindromic PlcR-box. Together with random mutagenesis experiments and interaction measurements using Peptides from distinct pherogroups, this structural analysis allows us to propose a molecular mechanism for this functional switch.

  • Peptide-binding dependent conformational changes regulate the transcriptional activity of the quorum-sensor NprR
    Nucleic Acids Research, 2013
    Co-Authors: Samira Zouhir, Didier Lereclus, Stephane Perchat, Magali Nicaise, Javier Perez, Beatriz Guimaraes, Sylvie Nessler
    Abstract:

    The transcriptional regulator NprR controls the expression of genes essential for the adaptative response of Bacillus cereus. NprR belongs to the RNPP family of directly regulated quorum sensors from Gram-positive bacteria. It is activated by the re- imported Signaling Peptide NprX. To elucidate the activation mechanism of this quorum-sensing system, we analyzed the conformation changes induced on binding of NprX. We solved the crystal structure of the NprR/NprX binary complex and characterized the apo form of NprR in solution. We demonstrated that apo NprR is a dimer that switches to a tetramer in the presence of NprX. Mutagenesis, and functional analysis allowed us to identify the protein and Peptide residues directly involved in the NprR activation process. Based on the comparison with the Rap proteins, we propose a model for the Peptide-induced conformational change allowing the apo dimer to switch to an active tetramer specifically recognizing target DNA sequences.

Leyla Slamti - One of the best experts on this subject based on the ideXlab platform.

  • CodY regulates the activity of the virulence quorum sensor PlcR by controlling the import of the Signaling Peptide PapR in Bacillus thuringiensis
    Frontiers in Microbiology, 2016
    Co-Authors: Leyla Slamti, Eugenie Huillet, Christelle Lemy, Celine Henry, Alain Guillot, Didier Lereclus
    Abstract:

    In Gram-positive bacteria, cell–cell communication mainly relies on cytoplasmic sensors of the RNPP family. Activity of these regulators depends on their binding to secreted Signaling Peptides that are imported into the cell. These quorum sensing regulators control important biological functions in bacteria of the Bacillus cereus group, such as virulence and necrotrophism. The RNPP quorum sensor PlcR, in complex with its cognate Signaling Peptide PapR, is the main regulator of virulence in B. cereus and Bacillus thuringiensis(Bt). Recent reports have shown that the global stationary phase regulator CodY, involved in adaptation to nutritional limitation, is required for the expression of virulence genes belonging to the PlcR regulon. However, the mechanism underlying this regulation was not described. Using genetics and proteomics approaches, we showed that CodY regulates the expression of the virulence genes through the import of PapR. We report that CodY positively controls the production of the proteins that compose the oligoPeptide permease OppABCDF, and of several other Opp-like proteins. It was previously shown that the pore components of this oligoPeptide permease, OppBCDF, were required for the import of PapR. However, the role of OppA, the substrate-binding protein (SBP), was not investigated. Here, we demonstrated that OppA is not the only SBP involved in the recognition of PapR, and that several other OppA-like proteins can allow the import of this Peptide. Altogether, these data complete our model of quorum sensing during the lifecycle of Bt and indicate that RNPPs integrate environmental conditions, as well as cell density, to coordinate the behavior of the bacteria throughout growth

  • structural basis for the activation mechanism of the plcr virulence regulator by the quorum sensing signal Peptide papr
    Proceedings of the National Academy of Sciences of the United States of America, 2013
    Co-Authors: Rosa Grenha, Didier Lereclus, Leyla Slamti, Magali Nicaise, Sylvie Nessler, Yacine Refes
    Abstract:

    The quorum-sensing regulator PlcR is the master regulator of most known virulence factors in Bacillus cereus. It is a helix-turn-helix (HTH)-type transcription factor activated upon binding of its cognate Signaling Peptide PapR on a tetratricoPeptide repeat-type regulatory domain. The structural and functional properties of PlcR have defined a new family of sensor regulators, called the RNPP family (for Rap, NprR, PrgX, and PlcR), in Gram-positive bacteria. To fully understand the activation mechanism of PlcR, we took a closer look at the conformation changes induced upon binding of PapR and of its target DNA, known as PlcR-box. For that purpose we have determined the structures of the apoform of PlcR (Apo PlcR) and of the ternary complex of PlcR with PapR and the PlcR-box from the plcA promoter. Comparison of the apoform of PlcR with the previously published structure of the PlcR–PapR binary complex shows how a small conformational change induced in the C-terminal region of the tetratricoPeptide repeat (TPR) domain upon Peptide binding propagates via the linker helix to the N-terminal HTH DNA-binding domain. Further comparison with the PlcR–PapR–DNA ternary complex shows how the activation of the PlcR dimer allows the linker helix to undergo a drastic conformational change and subsequent proper positioning of the HTH domains in the major groove of the two half sites of the pseudopalindromic PlcR-box. Together with random mutagenesis experiments and interaction measurements using Peptides from distinct pherogroups, this structural analysis allows us to propose a molecular mechanism for this functional switch.

  • a cell cell Signaling Peptide activates the plcr virulence regulon in bacteria of the bacillus cereus group
    The EMBO Journal, 2002
    Co-Authors: Leyla Slamti, Didier Lereclus
    Abstract:

    PlcR is a pleiotropic regulator that activates the expression of genes encoding various virulence factors, such as phospholipases C, proteases and hemolysins, in Bacillus thuringiensis and Bacillus cereus. Here we show that the activation mechanism is under the control of a small Peptide: PapR. The papR gene belongs to the PlcR regulon and is located 70 bp downstream from plcR. It encodes a 48-amino-acid Peptide. Disruption of the papR gene abolished expression of the PlcR regulon, resulting in a large decrease in hemolysis and virulence in insect larvae. We demonstrated that the PapR polyPeptide was secreted, then reimported via the oligoPeptide permease Opp. Once inside the cell, a processed form of PapR, presumably a pentaPeptide, activated the PlcR regulon by allowing PlcR to bind to its DNA target. This activating mechanism was found to be strain specific, with this specificity determined by the first residue of the penta Peptide.

Stephane Perchat - One of the best experts on this subject based on the ideXlab platform.

  • The Signaling Peptide NprX controlling sporulation and necrotrophism is imported into Bacillus thuringiensis by two oligoPeptide permease systems
    Molecular Microbiology, 2019
    Co-Authors: Thomas Dubois, Christelle Lemy, Stephane Perchat, Didier Lereclus
    Abstract:

    The infectious cycle of Bacillus thuringiensis in the insect host is regulated by quorum sensors of the RNPP family. The activity of these regulators is modulated by their cognate Signaling Peptides translocated into the bacterial cells by oligoPeptide permeases (Opp systems). In B. thuringiensis, the quorum sensor NprR is a bi-functional regulator that connects sporulation to necrotrophism. The binding of the Signaling Peptide NprX switches NprR from a dimeric inhibitor of sporulation to a tetrameric transcriptional activator involved in the necrotrophic lifestyle of B. thuringiensis. Here, we report that NprX is imported into the bacterial cells by two different oligoPeptide permease systems. The first one is Opp, the system known to be involved in the import of the Signaling Peptide PapR in B. thuringiensis and Bacillus cereus. The second, designated as Npp (NprX Peptide permease), was not previously described. We show that at least two substrate binding proteins (SBPs) are able to translocate NprX through OppBCDF. In contrast, we demonstrate that a unique SBP (NppA) can translocate NprX through NppDFBC. We identified the promoter of the npp operon, and we showed that transcription starts at the onset of stationary phase and is repressed by the nutritional regulator CodY during the exponential growth phase.

  • How Quorum Sensing Connects Sporulation to Necrotrophism in Bacillus thuringiensis.
    PLoS Pathogens, 2016
    Co-Authors: Stephane Perchat, Didier Lereclus, Antoine Talagas, Sandrine Poncet, Noureddine Lazar, Inès Li De La Sierra-gallay, Michel Gohar, Sylvie Nessler
    Abstract:

    Bacteria use quorum sensing to coordinate adaptation properties, cell fate or commitment to sporulation. The infectious cycle of Bacillus thuringiensis in the insect host is a powerful model to investigate the role of quorum sensing in natural conditions. It is tuned by communication systems regulators belonging to the RNPP family and directly regulated by re-internalized Signaling Peptides. One such RNPP regulator, NprR, acts in the presence of its cognate Signaling Peptide NprX as a transcription factor, regulating a set of genes involved in the survival of these bacteria in the insect cadaver. Here, we demonstrate that, in the absence of NprX and independently of its transcriptional activator function, NprR negatively controls sporulation. NprR inhibits expression of Spo0A-regulated genes by preventing the KinA-dependent phosphorylation of the phosphotransferase Spo0F, thus delaying initiation of the sporulation process. This NprR function displays striking similarities with the Rap proteins, which also belong to the RNPP family, but are devoid of DNA-binding domain and indirectly control gene expression via protein-protein interactions in Bacilli. Conservation of the Rap residues directly interacting with Spo0F further suggests a common inhibition of the sporulation phosphorelay. The crystal structure of apo NprR confirms that NprR displays a highly flexible Rap-like structure. We propose a molecular regulatory mechanism in which key residues of the bifunctional regulator NprR are directly and alternatively involved in its two functions. NprX binding switches NprR from a dimeric inhibitor of sporulation to a tetrameric transcriptional activator involved in the necrotrophic lifestyle of B. thuringiensis. NprR thus tightly coordinates sporulation and necrotrophism, ensuring survival and dissemination of the bacteria during host infection.

  • NprR, a moonlighting quorum sensor shifting from a phosphatase activity to a transcriptional activator
    Microbial Cell, 2016
    Co-Authors: Stephane Perchat, Samira Zouhir, Sylvie Nessler, Antoine Talagas, Sandrine Poncet-mouturat, Laurent Bouillaut, Didier Lereclus
    Abstract:

    Regulation of biological functions requires factors (proteins, Peptides or chemicals) able to sense and translate environmental conditions or any circumstances in order to modulate the transcription of a gene, the stability of a transcript or the activity of a protein. Quorum sensing is a regulation mechanism connecting cell density to the physiological state of a single cell. In bacteria, quorum sensing coordinates virulence, cell fate and commitment to sporulation and other adaptation properties. The critical role of such regulatory systems was demonstrated in pathogenicity and adaptation of bacteria from the Bacillus cereus group (i.e. B. cereus and Bacillus thuringiensis). Furthermore, using insects as a model of infection, it was shown that sequential activation of several quorum sensing systems allowed bacteria to switch from a virulence state to a necrotrophic lifestyle, allowing their survival in the host cadaver, and ultimately to the commitment into sporulation. The chronological development of these physiological states is directed by quorum sensors forming the RNPP family. Among them, NprR combines two distinct functions connecting sporulation to necrotrophism in B. thuringiensis. In the absence of its cognate Signaling Peptide (NprX), NprR negatively controls sporulation by acting as a phosphatase. In the presence of NprX, it acts as a transcription factor regulating a set of genes involved in the survival of the bacteria in the insect cadaver.

  • Peptide-binding dependent conformational changes regulate the transcriptional activity of the quorum-sensor NprR
    Nucleic Acids Research, 2013
    Co-Authors: Samira Zouhir, Didier Lereclus, Stephane Perchat, Magali Nicaise, Javier Perez, Beatriz Guimaraes, Sylvie Nessler
    Abstract:

    The transcriptional regulator NprR controls the expression of genes essential for the adaptative response of Bacillus cereus. NprR belongs to the RNPP family of directly regulated quorum sensors from Gram-positive bacteria. It is activated by the re- imported Signaling Peptide NprX. To elucidate the activation mechanism of this quorum-sensing system, we analyzed the conformation changes induced on binding of NprX. We solved the crystal structure of the NprR/NprX binary complex and characterized the apo form of NprR in solution. We demonstrated that apo NprR is a dimer that switches to a tetramer in the presence of NprX. Mutagenesis, and functional analysis allowed us to identify the protein and Peptide residues directly involved in the NprR activation process. Based on the comparison with the Rap proteins, we propose a model for the Peptide-induced conformational change allowing the apo dimer to switch to an active tetramer specifically recognizing target DNA sequences.

Mayumi Kimura - One of the best experts on this subject based on the ideXlab platform.

  • restoring serotonergic homeostasis in the lateral hypothalamus rescues sleep disturbances induced by early life obesity
    The Journal of Neuroscience, 2018
    Co-Authors: Mary Gazea, Alexandre V Patchev, Elmira Anderzhanova, Este Leidmaa, Anna Pissioti, C Flachskamm, Osborne F X Almeida, Mayumi Kimura
    Abstract:

    Early-life obesity predisposes to obesity in adulthood, a condition with broad medical implications including sleep disorders, which can exacerbate metabolic disturbances and disrupt cognitive and affective behaviors. In this study, we examined the long-term impact of transient peripubertal diet-induced obesity (ppDIO, induced between 4 and 10 weeks of age) on sleep–wake behavior in male mice. EEG and EMG recordings revealed that ppDIO increases sleep during the active phase but reduces resting-phase sleep quality. This impaired sleep phenotype persisted for up to 1 year, although animals were returned to a non-obesiogenic diet from postnatal week 11 onwards. To better understand the mechanisms responsible for the ppDIO-induced alterations in sleep, we focused on the lateral hypothalamus (LH). Mice exposed to ppDIO did not show altered mRNA expression levels of orexin and melanin-concentrating hormone, two Peptides that are important for sleep–wake behavior and food intake. Conversely, the LH of ppDIO-exposed mice had reduced contents of serotonin (5-hydroxytryptamine, 5-HT), a neurotransmitter involved in both sleep–wake and satiety regulation. Interestingly, an acute peripheral injection of the satiety-Signaling Peptide YY 3–36 increased 5-HT turnover in the LH and ameliorated the ppDIO-induced sleep disturbances, suggesting the therapeutic potential of this Peptide. These findings provide new insights into how sleep–wake behavior is programmed during early life and how peripheral and central signals are integrated to coordinate sleep. SIGNIFICANCE STATEMENT Adult physiology and behavior are strongly influenced by dynamic reorganization of the brain during puberty. The present work shows that obesity during puberty leads to persistently dysregulated patterns of sleep and wakefulness by blunting serotonergic Signaling in the lateral hypothalamus. It also shows that pharmacological mimicry of satiety with Peptide YY 3–36 can reverse this neurochemical imbalance and acutely restore sleep composition. These findings add insight into how innate behaviors such as feeding and sleep are integrated and suggest a novel mechanism through which diet-induced obesity during puberty imposes its long-lasting effects on sleep–wake behavior.

  • restoring serotonergic homeostasis in the lateral hypothalamus rescues sleep disturbances induced by early life obesity
    The Journal of Neuroscience, 2018
    Co-Authors: Mary Gazea, Alexandre V Patchev, Elmira Anderzhanova, Este Leidmaa, Anna Pissioti, C Flachskamm, Osborne F X Almeida, Mayumi Kimura
    Abstract:

    Early life obesity predisposes to obesity in adulthood, a condition with broad medical implications including sleep disorders; the latter can exacerbate metabolic disturbances and disrupt cognitive and affective behaviors. In this study, we examined the long-term impact of transient peripubertal diet-induced obesity (ppDIO, induced between 4 and 10 weeks of age) on sleep-wake behavior in male mice. Electroencephalographic and electromyographic recordings revealed that ppDIO increases sleep during the active phase but reduces resting-phase sleep quality. This impaired sleep phenotype persisted for up to one year although animals were returned to a non-obesogenic diet from postnatal week 11 onwards. To better understand the mechanisms responsible for the ppDIO-induced alterations in sleep, we focused on the lateral hypothalamus (LH). Mice exposed to ppDIO did not show altered mRNA expression levels of orexin and melanin-concentrating hormone, two Peptides that are important for sleep-wake behavior and food intake. On the other hand, the LH of ppDIO-exposed mice had reduced contents of serotonin, a neurotransmitter involved in both sleep-wake and satiety regulation. Interestingly, an acute peripheral injection of the satiety-Signaling Peptide YY 3-36 (PYY 3-36 ) increased serotonin turnover in the LH and ameliorated the ppDIO-induced sleep disturbances, suggesting the therapeutic potential of this Peptide. These findings provide new insights into how sleep-wake behavior is programmed during early life and how peripheral and central signals are integrated to coordinate sleep. Significance Statement Adult physiology and behavior are strongly influenced by dynamic reorganization of the brain during puberty. The present work shows that obesity during puberty leads to persistently dysregulated patterns of sleep and wakefulness by blunting serotonergic Signaling in the lateral hypothalamus. It also shows that pharmacological mimicry of satiety with Peptide YY 3-36 can reverse this neurochemical imbalance and acutely restore sleep composition. These findings add insight into how innate behaviors such as feeding and sleep are integrated and suggest a novel mechanism through which diet-induced obesity during puberty imposes its long-lasting effects on sleep-wake behavior.