Quorum Sensing Regulation of Competence and Bacteriocins in Streptococcus pneumoniae and mutans

Abstract

The human pathogens Streptococcus pneumoniae and Streptococcus mutans have both evolved complex quorum sensing (QS) systems that regulate the production of bacteriocins and the entry into the competent state, a requirement for natural transformation. Natural transformation provides bacteria with a mechanism to repair damaged genes or as a source of new advantageous traits. In S. pneumoniae, the competence pathway is controlled by the two-component signal transduction pathway ComCDE, which directly regulates SigX, the alternative sigma factor required for the initiation into competence. Over the past two decades, effectors of cellular killing (i.e., fratricides) have been recognized as important targets of the pneumococcal competence QS pathway. Recently, direct interactions between the ComCDE and the paralogous BlpRH pathway, regulating bacteriocin production, were identified, further strengthening the interconnections between these two QS systems. Interestingly, a similar theme is being revealed in S. mutans, the primary etiological agent of dental caries. This review compares the relationship between the bacteriocin and the competence QS pathways in both S. pneumoniae and S. mutans, and hopes to provide clues to regulatory pathways across the genus Streptococcus as a potential tool to efficiently investigate putative competence pathways in nontransformable streptococci.

The impact of type VI secretion system, bacteriocins and antibiotics on competition amongst Soft-RotEnterobacteriaceae: Regulation of carbapenem biosynthesis by iron and the transcriptional regulator Fur

“…These antimicrobials are diverse in their mechanism of action, targets, antagonistic and spatial range (20, 21). There is clearly a cost in the execution of these weapons, hence, by implication, regulation must be tightly modulated (26, 30-32). Over the years, many studies have interrogated mechanisms of the different antimicrobials ‘singularly’ however fewer have systematically investigated these factors in concert.…”

In silico analysis of the competition between Streptococcus sanguinis and Streptococcus mutans in the dental biofilm

“…10,12 The QS regulates the global cellular response to environmental changes, including the ability to incorporate foreign DNA (competence) and biofilm development. 13 Besides mutacin production, the QS has been implicated in S. mutans competition within the dental biofilm, as this complex system allows bacterial cells to adapt and survive under stress conditions, for example those imposed by acid production. 14,15 Compared with S. mutans, the understanding of QS in S. sanguinis is rather limited.…”

Threshold regulation and stochasticity from the MecA/ClpCP proteolytic system inStreptococcus mutanscompetence

“…Tian et al, 2013;Shanker;Federle, 2016). ComX activates late competence genes that include 82 the nine-gene operon comYA-I, which contains seven genes that are required for transformation 83(Merritt et al, 2005).Transcription of comX can be triggered by either of two quorum sensing 84 peptides: CSP (competence stimulating peptide) or XIP (SigX-inducing peptide).…”