Regulation of virulence by a regulatory RNA in GAS

The capacity of pathogens to cause disease depends strictly on the fine-tune regulated expression of their virulence factors. Recent findings indicate that the control of virulence is far more complex than expected and involves in many cases RNA molecules. Over the last twenty years, many researchers have investigated important aspects of Streptococcus pyogenes pathogenesis. However concept of regulatory RNAs controlling GAS virulence has been hypothesized so far but no further validated. In S. pyogenes, the pleiotropic effect locus, pel, which comprises incidentally sagA, the structural gene for the hemolysin SLS (streptolysin S) has already been described as a regulator of exoprotein expression. We recently demonstrated that in a M1 reference strain, the untranslated pel mRNA itself rather than a translational product is an effector of exoprotein regulation at transcriptional and post-trasncriptional levels. This research proposal focuses on the elucidation of the mechanism of action of the pel RNA molecule. Our first objective is to establish the structure of the pel RNA and analyze the domains crucial for its stability and activity. Second, we intend to delineate the pathway(s) downstream of the pel RNA, since it stands to reason that pel RNA is not mediating its effects directly on target genes. Third, we will attempt to identify additional targets of the pel RNA molecule. An understanding of the pel RNA regulatory circuit(s) will contribute to a better knowledge of the streptococcal exoprotein response in GAS. This research is particularly important in times of new aggressiveness of gram- positive infections and dramatically uprising emergence of antibiotic resistance bacterial pathogens.

The capacity of pathogens to cause disease depends strictly on the fine-tune regulated expression of their virulence factors. Recent findings indicate that the control of virulence is far more complex than expected and involves in many cases RNA molecules. Over the last twenty years, many researchers have investigated important aspects of Streptococcus pyogenes pathogenesis. However concept of regulatory RNAs controlling GAS virulence has been hypothesized so far but no further validated. In S. pyogenes, the pleiotropic effect locus, pel, which comprises incidentally sagA, the structural gene for the hemolysin SLS (streptolysin S) has already been described as a regulator of exoprotein expression. We recently demonstrated that in a M1 reference strain, the untranslated pel mRNA itself rather than a translational product is an effector of exoprotein regulation at transcriptional and post-trasncriptional levels. This research proposal focuses on the elucidation of the mechanism of action of the pel RNA molecule. Our first objective is to establish the structure of the pel RNA and analyze the domains crucial for its stability and activity. Second, we intend to delineate the pathway(s) downstream of the pel RNA, since it stands to reason that pel RNA is not mediating its effects directly on target genes. Third, we will attempt to identify additional targets of the pel RNA molecule. An understanding of the pel RNA regulatory circuit(s) will contribute to a better knowledge of the streptococcal exoprotein response in GAS. This research is particularly important in times of new aggressiveness of gram- positive infections and dramatically uprising emergence of antibiotic resistance bacterial pathogens.