title: Subpopulation-specific transcriptome analysis of competence-stimulating-peptide-induced Streptococcus mutans.
abstract: Competence-stimulating-peptide (CSP)-mediated competence development in Streptococcus mutans is a transient and biphasic process, since only a subpopulation induces the expression of ComX in the presence of CSP, and the activation of the DNA uptake machinery in this fraction shuts down ~3 to 4 h postinduction. Here, we combine for the first time, to our knowledge, the bacterial flow-cytometric sorting of cells and subpopulation-specific transcriptome analysis of both the competent and noncompetent fraction of CSP-treated S. mutans cells. Sorting was guided by a ComX-green fluorescent protein (ComX-GFP) reporter, and the transcriptome analysis demonstrated the successful combination of both methods, because a strong enrichment of transcripts for comX and its downstream genes was achieved. Three two-component systems were expressed in the competent fraction, and among them was ComDE. Moreover, the recently identified regulator system ComR/S was expressed exclusively in the competent fraction. In contrast, the expression of bacteriocin-related genes was at the same level in all cells. GFP reporter strains for ComE and CipB (mutacin V) confirmed this expression pattern on the single-cell level. Fluorescence microscopy revealed that some ComX-expressing cells committed autolysis in an early stage of competence initiation. In viable ComX-expressing cells, the uptake of DNA could be shown on the single-cell level. This study demonstrates that all cells in the population respond to CSP through the activation of bacteriocin-related genes. Some of these cells start to activate ComX expression but then segregate into two subpopulations, one becoming competent and another one that lyses, resulting in intrapopulation diversity.
authors.affiliation: Helmholtz Centre for Infection Research, Research Group Microbial Communication, Braunschweig, Germany. Andre.Lemme@helmholtz-hzi.de
authors.forename: André
authors.initials: A
authors.lastname: Lemme
authors.forename: Lothar
authors.initials: L
authors.lastname: Gröbe
authors.forename: Michael
authors.initials: M
authors.lastname: Reck
authors.forename: Jürgen
authors.initials: J
authors.lastname: Tomasch
authors.forename: Irene
authors.initials: I
authors.lastname: Wagner-Döbler
mesh_terms: D019677:Artificial Gene Fusion; D001426:Bacterial Proteins / Q000378:metabolism*; D001430:Bacteriocins / Q000378:metabolism*; D005434:Flow Cytometry; D020869:Gene Expression Profiling; D015964:Gene Expression Regulation, Bacterial; D017930:Genes, Reporter; D049452:Green Fluorescent Proteins / Q000235:genetics / Q000378:metabolism; D013295:Streptococcus mutans / Q000145:classification* / Q000235:genetics*
chemical_list: D001426:Bacterial Proteins; D001430:Bacteriocins; C423628:competence factor, Streptococcus; C000607161:mutacin V, Streptococcus mutans; D049452:Green Fluorescent Proteins