Phenotype-specific small non-protein-coding RNAs of Staphylococcus aureus
Abstract number: P738
Abu-Qatouseh L.F., Chinni S.V., Rozhdestvensky T.S., Seggewiss J., Proctor R.A., Peters G., Brosius J., von Eiff C., Becker K.
Objectives: The formation of phenotypic variants of Staphylococcus aureus, in particular of the small-colony variant (SCV) phenotype, is only partially understood. Non-protein-coding RNA (npcRNA) genes have been found to act as key regulatory players in response to environmental changes and host signals. So far, only few npcRNAs have been described in Gram-positive bacteria including staphylococci.
Methods: Since growth rate specific-expression was observed for bacterial npcRNA, we performed identification of npcRNA candidates using total RNA of S. aureus isolated from different growth stages of an isogenic clinical strain pair displaying the normal and the SCV phenotype. Total RNA was extracted and size-fractionated (from 10 to 500 nt) and two separate cDNA libraries were constructed. A total of 10,000 cDNA clones were randomly sequenced and analysed by BLASTN database search. Northern blot analyses were applied for conformation of the expression of novel npcRNAs candidates.
Results: Overall, 183 putative candidates for novel npcRNAs were identified. The expression of 34 of the identified npcRNAs was experimentally validated and confirmed by Northern blot analyses. Growth phase specific regulation was detected for 23 npcRNAs. Of particular interest, S. aureus phenotype-specific expression of six npcRNAs was found: Whereas five of the identified novel npcRNAs were specifically expressed only in the normal phenotype, expression of one of the novel npcRNA candidates was restricted to the SCV phenotype. Most of the novel npcRNAs were stage specific-regulated in SCVs with the majority being down regulated at the late growth of SCVs. In addition, several of the newly identified S. aureus npcRNAs exhibited relationship to S. aureus pathogenicity. Some of the experimentally verified npcRNAs were originated from pathogenicity islands indicating a putative role in the regulation of S. aureus virulence.
Conclusion: For the first time, a classification of npcRNAs based on their differential expression between the normal and the SCV phenotype of S. aureus was established. Thus, a role of npcRNAs in the regulation of the divergent phenotype-associated behaviour of S. aureus in the host environment might be assumed. Further studies are warranted to elucidate the potential functions of the novel npcRNAs and their impact on the pathogenesis of S. aureus infections.
|Session name:||19th European Congress of Clinical Microbiology and Infectious Diseases|
|Location:||Helsinki, Finland, 16 - 19 May 2009|
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