Identification and characterization of novel small non-protein-coding RNAs of Staphylococcus aureus

  • Luay Abu-Qatouseh, Institute of Medical Microbiology, University Hospital of Münster, Germany
  • Jochen Seggewiß, Institute of Medical Microbiology, University Hospital of Münster, Germany
  • Suresh Chinni, Institute of Experimental Pathology (ZMBE), University Hospital of Münster, Germany
  • Timofey Rozhdestvensky, Institute of Experimental Pathology (ZMBE), University Hospital of Münster, Germany
  • Richard Proctor, Department of Medical Microbiology and Immunology, University of Wisconsin, School of Medicine and Public Health, Madison, United States
  • Georg Peters, Institute of Medical Microbiology, University Hospital of Münster, Germany
  • Christof von Eiff, Institute of Medical Microbiology, University Hospital of Münster, Germany
  • Karsten Becker, Institute of Medical Microbiology, University Hospital of Münster, Germany

    • In recent years, small non-protein-coding RNAs (npcRNAs) have attracted great attention as ubiquitous regulators of expression of genes involved in virulence and growth of bacterial pathogens in response to host signals. However, few npcRNAs have been identified in Gram-positive species, including staphylococci. Total RNA from different growth phases of clinical isolates of Staphylococcus aureus was extracted and size-fractionated (from 10 to 500 nt). To identify small npcRNAs in isogenic clinical S. aureus strains exhibiting the normal phenotype and the small-colony variant (SCV) phenotype, two separate cDNA libraries were constructed. About 10,000 clones of the cDNA libraries were randomly chosen, sequenced, and analysed by BLASTN database search. For conformation purposes, Northern blots were applied. A total of 185 putative candidates for novel small npcRNAs in S. aureus were identified. Most of these npcRNA candidates (48%) were located in antisense orientation or in the intergenic regions of predicted or hypothetical protein coding genes (40%). Interestingly, some of these small npcRNAs were specific to the S. aureus phenotype and were expressed in a growth dependent manner. In addition, some of the experimentally verified npcRNAs were originated from the pathogenicity islands of the genome indicating a potential role in the regulation of S. aureus virulence. Beside implications in the understanding of virulence, novel S. aureus npcRNA candidates may shed a light on the formation of different phenotypes of this pathogen. Further investigations of the functional aspects of these novel npcRNAs might provide new strategies in the control of S. aureus infections.