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

Enterococcal Rgg-Like Regulator ElrR Activates Expression of the elrA Operon

“…Both PrgX and PlcR regulate the transcription of their target genes in response to a signal peptide. Peptide binding to PlcR enhances DNA binding through drastic conformational and oligomerization changes promoting transcription activation of cognate target genes (58,59). In contrast, PrgX responds to two competing signaling peptides and acts as a transcriptional repressor.…”

Rgg protein structure–function and inhibition by cyclic peptide compounds

“…S3 A-C) (33) and the RNPP proteins PlcR and PrgX (Fig. S3 D-F) (15,34); however, in the Rgg2 Sd structure (and the Rgg Sd -CsA structure described below) the Rgg2 Sd DBDs are covalently linked across the dimerization interface by a disulfide bond between the α4 helices ( Fig. 2A and Fig.…”

“…The Rap proteins are phosphatases and transcriptional antiactivators, whereas NprR, PlcR, and PrgX are DNA-binding transcription factors. Structure-function studies revealed that Rap, NprR, PlcR, and PrgX (the RNPP family proteins) use a structurally similar C-terminal tetratricopeptide (TPR)-like repeat domain to bind their cognate peptide pheromones (12)(13)(14)(15)(16)(17)(18)(19).…”

Sinonasal T2R-Mediated Nitric Oxide Production in Response to Bacillus Cereus

“…Together, these findings strongly indicated that the microbial product was not a peptide, the typical type of quorumsensing molecules used by gram-positive bacteria, 28 including B. cereus. 29 It is possible that the product that elicited the response was not unique to B. cereus and may be shared by pathogens more commonly associated with respiratory disease. Although the specific identity of the active B. cereus CM product remains unknown, high-performance liquid chromatography (HPLC) and mass spectroscopy are feasible future options for isolation and identification.…”