The regulatory role of five small noncoding RNAs in Streptococcus pneumoniae

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The two component regulatory system CiaRH of Streptococcus pneumoniae is implicated in ß-lactam resistance, lytic processes, genetic competence, and virulence. The CiaR regulon consists of 24 genes including five small non-coding RNAs (csRNAs). A first search for csRNA targets revealed three genes. Two of them, comC and spr0081, are downregulated by the csRNAs in the wild type strain, while the third, comA, is regulated only in a strain overexpressing all csRNAs. In this strain, genetic competence is blocked as a consequence of com gene repression by csRNA overproduction. In addition, csRNAs are implicated in ß-lactam resistance, but their molecular targets in this process are not yet known. In the project applied here, phenotypic consequences of the established csRNA regulations will be explored in further detail. The role of individual csRNAs in the regulatory process and the contribution of single residues in csRNAs to target binding will be analyzed. To find new targets and interaction partners of the csRNAs, bioinformatics, proteome analysis, and a cDNA deep sequencing approach will be pursued. New regulatory interactions will be evaluated by in vivo regulation studies and in vitro csRNA binding assays. Defining new targets and regulatory processes should provide a comprehensive view on csRNA activities and their impact on the physiology of S. pneumoniae.