In Vitro Analysis of Predicted DNA-Binding Sites for the Stl Repressor of the Staphylococcus aureus SaPIBov1 Pathogenicity Island

PLoS One. 2016 Jul 7;11(7):e0158793. doi: 10.1371/journal.pone.0158793. eCollection 2016.


The regulation model of the Staphylococcus aureus pathogenicity island SaPIbov1 transfer was recently reported. The repressor protein Stl obstructs the expression of SaPI proteins Str and Xis, latter which is responsible for mobilization initiation. Upon Φ11 phage infection of S. aureus. phage dUTPase activates the SaPI transfer via Stl-dUTPase complex formation. Our aim was to predict the binding sites for the Stl repressor within the S. aureus pathogenicity island DNA sequence. We found that Stl was capable to bind to three 23-mer oligonucleotides, two of those constituting sequence segments in the stl-str, while the other corresponding to sequence segment within the str-xis intergenic region. Within these oligonucleotides, mutational analysis revealed that the predicted binding site for the Stl protein exists as a palindromic segment in both intergenic locations. The palindromes are built as 6-mer repeat sequences involved in Stl binding. The 6-mer repeats are separated by a 5 oligonucleotides long, nonspecific sequence. Future examination of the interaction between Stl and its binding sites in vivo will provide a molecular explanation for the mechanisms of gene repression and gene activation exerted simultaneously by the Stl protein in regulating transfer of the SaPIbov1 pathogenicity island in S. aureus.

MeSH terms

  • Bacterial Proteins / genetics
  • Binding Sites
  • DNA, Bacterial / analysis*
  • Genome, Bacterial
  • Genomic Islands
  • Oligonucleotides
  • Promoter Regions, Genetic
  • Pyrophosphatases / genetics
  • Repressor Proteins / genetics*
  • Repressor Proteins / metabolism
  • Staphylococcus Phages / genetics*
  • Staphylococcus aureus / genetics*


  • Bacterial Proteins
  • DNA, Bacterial
  • Oligonucleotides
  • Repressor Proteins
  • Pyrophosphatases
  • dUTP pyrophosphatase

Grants and funding

This work was supported by grants from the National Institute for Research and Innovation (NKFIH) (OTKA NK 84008, OTKA K109486), the Baross program of the New Hungary Development Plan (3DSTRUCT, OMFB-00266/2010 REG-KM-09-1- 2009-0050), the Hungarian Academy of Sciences (TTK IF-28/ 2012), the MedinProt program of the Hungarian Academy of Sciences, the European Commission FP7 BioStruct-X project (contract No. 283570), and CRP/HUN14-01 ICGEB Research Grant to BGV. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.