Sharply Tuned pH Response of Genetic Competence Regulation in Streptococcus mutans: a Microfluidic Study of the Environmental Sensitivity of comX

• DOI: 10.1128/aem.01421-15
• Publication Date: 2015-06-13T03:30:53Z
• Authors: Minjun Son; Delaram Ghoreishi; Sang-Joon Ahn; Robert A. Burne; Stephen J. Hagen
• Keywords: Bacteriological Techniques; 0303 health sciences; Gene Expression Profiling; Microfluidics; Gene Expression Regulation, Bacterial; Hydrogen-Ion Concentration; DNA Transformation Competence; Streptococcus mutans; 03 medical and health sciences; Bacterial Proteins; Promoter Regions, Genetic; Protein Binding; Transcription Factors

Genetic competence in Streptococcus mutans is a transient state that regulated response to multiple environmental inputs. These include extracellular pH and the concentrations of two secreted peptides, designated CSP (competence-stimulating peptide) XIP (comX-inducing peptide). The role cues regulating can be difficult disentangle from effects organism's physiological its chemical modification environment. We used microfluidics control environment study activation key gene comX. find comX promoter (PcomX) responds or only when lies within narrow window, about 1 unit wide, near 7. Within this range, elicits strong PcomX subpopulation cells, whereas outside range proportion cells expressing declines sharply. Likewise, most sensitive window. While previous work suggested may become refractory stimulus as exit early exponential phase, our microfluidic data show dominates determining sensitivity CSP. are consistent with an effect on ComR/ComS system, which has direct over transcription S. mutans.