Synthesis of group A streptococcal virulence factors is controlled by a regulatory RNA molecule

Abstract

SummaryThe capacity of pathogens to cause disease depends strictly on the regulated expression of their virulence factors. In this study, we demonstrate that the untranslated mRNA of the recently described streptococcal p leiotropic e ffect l ocus ( pel ), which incidentally contains sagA , the structural gene for streptolysin S, is an effector of virulence factor expression in group A beta-haemolytic streptococci (GAS). Our data suggest that the regulation by pel RNA occurs at both transcriptional (e.g. emm , sic , nga ) and post-transcriptional (e.g. SpeB) levels. We could exclude the possibility that the pel phenotype was linked to a polar effect on downstream genes ( sagB-I ). Remarkably, the RNA effector is regulated in a growth phase-dependent fashion and we provide evidence that pel RNA expression is induced by conditioned media.

Analysis of the Transcriptome of Group A Streptococcus in Mouse Soft Tissue Infection

“…60 The untranslated mRNA of the pleiotropic effect locus (pel), which incidentally contains sagA, also acts as an antisense RNA transcriptional regulator, augmenting GAS virulence factor expression [SIC, M-protein, extracellular NAD-glycohydrolase (NADase encoded by nga/spn), plasminogen activator streptokinase encoded by ska, and SpeB] when pel RNA expression is induced. 61,62 We detected abundant sagA transcripts; thus pel-induced virulence gene expression may be predicted, as was observed in this study for all but nga (ranked 780th in WT extracts). Therefore, these results, when coupled with the elevated expression of the neutrophil chemoattractant (interleukin-8)-cleaving SpyCEP protease (ranked 97th), 30 support the idea that coordinated, increased expression of sic, spd, sagA, speB, and spyCEP likely accounts for lack of inflammatory cells present at GAS sites in deep tissues.…”

Group A Streptococcus Activates Type I Interferon Production and MyD88-dependent Signaling without Involvement of TLR2, TLR4, and TLR9

“…S. pyogenes serotype M1 (ATCC 700294) is a clinical strain originally isolated from an infected wound. The isogenic sagA-and slo-deficient mutants were constructed using a thermosensitive strategy described previously (26). First, using wild-type genomic DNA as template and primers containing flanking restriction sites, a 1111-bp sagA upstream fragment (primers OLEC120/OLEC143), a 1200-bp sagA downstream fragment (primers OLEC123/OLEC144), a 1159-bp slo upstream fragment (primers OLEC248/OLEC249), and a 1033-bp slo downstream fragment (primers OLEC250/ OLEC251) were amplified.…”

“…First, using wild-type genomic DNA as template and primers containing flanking restriction sites, a 1111-bp sagA upstream fragment (primers OLEC120/OLEC143), a 1200-bp sagA downstream fragment (primers OLEC123/OLEC144), a 1159-bp slo upstream fragment (primers OLEC248/OLEC249), and a 1033-bp slo downstream fragment (primers OLEC250/ OLEC251) were amplified. After digestion with the respective restriction enzymes, the upstream and downstream fragments were cloned into thermo-sensitive plasmids pRDN18 (sagAdeficient mutant) and pEC84 (slo-deficient mutant) (26). After introduction of the recombinant plasmids into S. pyogenes ATCC 700294, a series of temperature shifts with appropriate antibiotic selection was performed, thus leading to the final deficient mutants (strain EC548 (sagA-deficient mutant) and EC997 (slo-deficient mutant)) in which the entire coding sequence of the gene was deleted in a nonpolar fashion.…”

Small RNAs in streptococci

“…1 and 2). Six sRNAs (FasX, Pel, RivX, 4.5S RNA, tracrRNA and crRNAs), 19,[42][43][44][45] were demonstrated to regulate virulence in S. pyogenes, among which, tracrRNA and crRNAs 19 were recently The numbers in plain letters indicate the total number of predicted srNAs whereas the numbers in bold letters indicate the number of validated srNAs. Please refer to the main text for all other abbreviations.…”