title: Structural basis for the activation mechanism of the PlcR virulence regulator by the quorum-sensing signal peptide PapR.
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.
authors.affiliation: Laboratoire d'Enzymologie et Biochimie Structurales, Unité Propre de Recherche 3082, Centre National de la Recherche Scientifique, 91198 Gif sur Yvette, France.
authors.forename: Rosa
authors.initials: R
authors.lastname: Grenha
authors.forename: Leyla
authors.initials: L
authors.lastname: Slamti
authors.forename: Magali
authors.initials: M
authors.lastname: Nicaise
authors.forename: Yacine
authors.initials: Y
authors.lastname: Refes
authors.forename: Didier
authors.initials: D
authors.lastname: Lereclus
authors.forename: Sylvie
authors.initials: S
authors.lastname: Nessler
mesh_terms: D000595:Amino Acid Sequence; D001059:Apoproteins / Q000737:chemistry / Q000235:genetics / Q000378:metabolism; D001409:Bacillus cereus / Q000235:genetics / Q000378:metabolism; D001413:Bacillus thuringiensis / Q000235:genetics / Q000378:metabolism; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D001483:Base Sequence; D001665:Binding Sites; D018360:Crystallography, X-Ray; D004269:DNA, Bacterial / Q000737:chemistry / Q000235:genetics; D005798:Genes, Bacterial; D008958:Models, Molecular; D008969:Molecular Sequence Data; D011401:Promoter Regions, Genetic; D011487:Protein Conformation; D054730:Protein Interaction Domains and Motifs; D055503:Protein Multimerization; D053038:Quorum Sensing; D017386:Sequence Homology, Amino Acid; D055672:Static Electricity; D015534:Trans-Activators / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014774:Virulence
chemical_list: D001059:Apoproteins; D001426:Bacterial Proteins; D004269:DNA, Bacterial; C466079:PapR protein, Bacillus cereus; C099480:PlcR protein, Bacillus; D015534:Trans-Activators