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The signaling peptide NprX controlling sporulation and necrotrophism is imported into Bacillus thuringiensis by two oligopeptide permease systems
Author(s) -
Dubois Thomas,
Lemy Christelle,
Perchat Stéphane,
Lereclus Didier
Publication year - 2019
Publication title -
molecular microbiology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.857
H-Index - 247
eISSN - 1365-2958
pISSN - 0950-382X
DOI - 10.1111/mmi.14264
Subject(s) - bacillus thuringiensis , biology , oligopeptide , permease , quorum sensing , operon , chemotaxis , peptide , regulator , biochemistry , microbiology and biotechnology , transporter , bacteria , gene , virulence , genetics , receptor , escherichia coli
Summary 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 ( N prX p eptide p ermease), 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.