title: Direct involvement of DprA, the transformation-dedicated RecA loader, in the shut-off of pneumococcal competence.
abstract: Natural bacterial transformation is a genetically programmed process allowing genotype alterations that involves the internalization of DNA and its chromosomal integration catalyzed by the universal recombinase RecA, assisted by its transformation-dedicated loader, DNA processing protein A (DprA). In Streptococcus pneumoniae, the ability to internalize DNA, known as competence, is transient, developing suddenly and stopping as quickly. Competence is induced by the comC-encoded peptide, competence stimulating peptide (CSP), via a classic two-component regulatory system ComDE. Upon CSP binding, ComD phosphorylates the ComE response-regulator, which then activates transcription of comCDE and the competence-specific σ(X), leading to a sudden rise in CSP levels and rendering all cells in a culture competent. However, how competence stops has remained unknown. We report that DprA, under σ(X) control, interacts with ComE∼P to block ComE-driven transcription, chiefly impacting σ(X) production. Mutations of dprA specifically disrupting interaction with ComE were isolated and shown to map mainly to the N-terminal domain of DprA. Wild-type DprA but not ComE interaction mutants affected in vitro binding of ComE to its promoter targets. Once introduced at the dprA chromosomal locus, mutations disrupting DprA interaction with ComE altered competence shut-off. The absence of DprA was found to negatively impact growth following competence induction, highlighting the importance of DprA for pneumococcal physiology. DprA has thus two key roles: ensuring production of transformants via interaction with RecA and competence shut-off via interaction with ComE, avoiding physiologically detrimental consequences of prolonged competence. Finally, phylogenetic analyses revealed that the acquisition of a new function by DprA impacted its evolution in streptococci relying on ComE to regulate comX expression.
authors: Laboratoire de Microbiologie et Génétique Moléculaires-Unité Mixte de Recherche 5100, Centre National de la Recherche Scientifique, F-31000 Toulouse, France.
authors: Nicolas
authors: N
authors: Mirouze
authors: Mathieu A
authors: MA
authors: Bergé
authors: Anne-Lise
authors: AL
authors: Soulet
authors: Isabelle
authors: I
authors: Mortier-Barrière
authors: Yves
authors: Y
authors: Quentin
authors: Gwennaele
authors: G
authors: Fichant
authors: Chantal
authors: C
authors: Granadel
authors: Marie-Françoise
authors: MF
authors: Noirot-Gros
authors: Philippe
authors: P
authors: Noirot
authors: Patrice
authors: P
authors: Polard
authors: Bernard
authors: B
authors: Martin
authors: Jean-Pierre
authors: JP
authors: Claverys
mesh_terms: D001426:Bacterial Proteins / Q000096:biosynthesis / Q000235:genetics / Q000378:metabolism*; D061269:DNA Transformation Competence / Q000502:physiology*; D015964:Gene Expression Regulation, Bacterial / Q000502:physiology; D008565:Membrane Proteins / Q000235:genetics / Q000378:metabolism*; D009154:Mutation; D017434:Protein Structure, Tertiary; D011938:Rec A Recombinases / Q000235:genetics / Q000378:metabolism*; D013296:Streptococcus pneumoniae / Q000235:genetics / Q000378:metabolism*; D014157:Transcription Factors / Q000096:biosynthesis / Q000235:genetics; D014158:Transcription, Genetic / Q000502:physiology
chemical_list: D001426:Bacterial Proteins; C103179:ComE protein, Streptococcus pneumoniae; C120829:ComX protein, Streptococcus; C093815:DprA protein, bacteria; D008565:Membrane Proteins; D014157:Transcription Factors; C423628:competence factor, Streptococcus; D011938:Rec A Recombinases