Mutation of luxS affects growth and virulence factor expression in Streptococcus pyogenes

Abstract

Adaptive responses of bacteria that involve sensing the presence of other bacteria are often critical for proliferation and the expression of virulence characteristics. The autoinducer II (AI‐2) pathway has recently been shown to be a mechanism for sensing other bacteria that is highly conserved among diverse bacterial species, including Gram‐positive pathogens. However, a role for this pathway in the regulation of virulence factors in Gram‐positive pathogens has yet to be established. In this study, we have inactivated luxS, an essential component of the AI‐2 pathway, in the Gram‐positive pathogen Streptococcus pyogenes. Analyses of the resulting mutants revealed the aberrant expression of several virulence properties that are regulated in response to growth phase, including enhanced haemolytic activity, and a dramatic reduction in the expression of secreted proteolytic activity. This latter defect was associated with a reduced ability to secrete and process the precursor of the cysteine protease (SpeB) as well as a difference in the timing of expression of the protease. Enhanced haemolytic activity of the luxS strain was also shown to be linked with an increased expression of the haemolysin S‐associated gene sagA. Disruptions of luxS in these mutants also produced a media‐dependent growth defect. Finally, an allelic replacement analysis of an S. pyogenes strain with a naturally occurring insertion of IS1239 in luxS suggested a mechanism for modulation of virulence during infection. Results from this study suggest that luxS makes an important contribution to the regulation of S. pyogenes virulence factors.

Role ofluxSinBacillus anthracisgrowth and virulence factor expression

“…[30][31][32][33][34][35][36]55 Furanone-1 [(5Z)-4-bromo-5-(bromomethylene)-3-butyl-2(5H)-furanone] has been shown to inhibit >70% of the AI-2 regulated genes in E. coli, has been observed in Streptococcus pyogenes. 50 In total, these data demonstrate that the altered phenotypes in the ∆luxS strain are due to luxS disruption and not to other undefined coincident mutations.…”

Heterologous Expression of sahH Reveals That Biofilm Formation Is Autoinducer-2-independent in Streptococcus sanguinis but Is Associated with an Intact Activated Methionine Cycle

“…Consequently, in our study we examined for the suitability of such heterologous complementation in a Gram-positive bacterium. This could be of broad interest because in several single and multispecies studies, especially on human pathogenic streptococci, a multitude of effects was observed, investigating luxS deletion mutants; in the exclusively human pathogen Streptococcus pyogenes, LuxS mutation had a pronounced effect on many virulence traits, including hemolytic and proteolytic activity as well as acid tolerance (17)(18)(19). Similar pleiotropic effects were observed in another important human pathogen, Streptococcus pneumoniae.…”

Potential Emergence of Multi-quorum Sensing Inhibitor Resistant (MQSIR) Bacteria

“…Clostridium are noted to contain either single or multiple QSS, such as: (1) LuxS, (2) Agr, (3) Agr2 that are regulated by peptide signals e.g., AIP ( Table 1) [24][25][26][27][28][29]. Table 1) [30][31][32][33][34].…”