title: Regulation of competence for natural transformation in streptococci.
abstract: Natural DNA transformation is a lateral gene transfer mechanism during which bacteria take up naked DNA from their environment and stably integrate it in their genome. The proteins required for this process are conserved between species and are produced during a specific physiological state known as competence. Although natural transformation drives genome plasticity and adaptability, it is also likely to cause deleterious effects in the chromosome of the recipient bacteria and negatively impact cell growth. The competence window is thus generally tightly regulated in response to species-specific environmental conditions and limited to a proportion of the cell population. In streptococci species, the entry into competence is dictated by the amount of the competence sigma factor σ(X), the master regulator of natural transformation in those species. The Streptococcus genus includes 7 phylogenetic groups that have evolved different regulatory circuits to govern natural transformation. Here, we review the current knowledge on transcriptional and post-transcriptional mechanisms that control the activity of σ(X) at the whole population and the single-cell level, with an emphasis on growth conditions that modulate their activation. Recent findings regarding competence regulation by the ComCDE and ComRS cell-cell signalling pathways and the Clp proteolytic system are specifically highlighted.
authors.affiliation: Institut des Sciences de la Vie, Université catholique de Louvain, Place Croix du Sud 5, B-1348 Louvain-la-Neuve, Belgium. Electronic address: laetitia.fontaine@uclouvain.be.
authors.forename: Laetitia
authors.initials: L
authors.lastname: Fontaine
authors.affiliation: Institut des Sciences de la Vie, Université catholique de Louvain, Place Croix du Sud 5, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Astrid
authors.initials: A
authors.lastname: Wahl
authors.affiliation: Institut des Sciences de la Vie, Université catholique de Louvain, Place Croix du Sud 5, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Maud
authors.initials: M
authors.lastname: Fléchard
authors.affiliation: Institut des Sciences de la Vie, Université catholique de Louvain, Place Croix du Sud 5, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Johann
authors.initials: J
authors.lastname: Mignolet
authors.affiliation: Institut des Sciences de la Vie, Université catholique de Louvain, Place Croix du Sud 5, B-1348 Louvain-la-Neuve, Belgium.
authors.forename: Pascal
authors.initials: P
authors.lastname: Hols
mesh_terms: D001426:Bacterial Proteins / Q000235:genetics; D061269:DNA Transformation Competence; D015964:Gene Expression Regulation, Bacterial; D006801:Humans; D010641:Phenotype; D010675:Pheromones / Q000378:metabolism; D059748:Proteolysis; D012808:Sigma Factor / Q000235:genetics / Q000378:metabolism; D015398:Signal Transduction; D013291:Streptococcus / Q000145:classification / Q000502:physiology*; D014157:Transcription Factors / Q000235:genetics; D014169:Transformation, Bacterial
chemical_list: D001426:Bacterial Proteins; C120829:ComX protein, Streptococcus; D010675:Pheromones; D012808:Sigma Factor; D014157:Transcription Factors
keywords: Bistability; Clp proteolytic system; ComCDE; ComRS; ComX; Environmental stress