Inhibiting the Growth of Methicillin-Resistant Staphylococcus Aureus in Vitro With Antisense Peptide Nucleic Acid Conjugates Targeting the ftsZ Gene

Int J Infect Dis. 2015 Jan;30:1-6. doi: 10.1016/j.ijid.2014.09.015. Epub 2014 Nov 5.

Abstract

Background: The increasing emergence of clinical infections caused by methicillin-resistant Staphylococcus aureus (MRSA) challenges existing therapeutic options and highlights the need to develop novel treatment strategies. The ftsZ gene is essential to bacterial cell division.

Methods: In this study, two antisense peptide nucleic acids (PNAs) conjugated to a cell-penetrating peptide were used to inhibit the growth of MRSA. PPNA1, identified with computational prediction and dot-blot hybridization, is complementary to nucleotides 309-323 of the ftsZ mRNA. PPNA2 was designed to target the region that includes the translation initiation site and the ribosomal-binding site (Shine-Dalgarno sequence) of the ftsZ gene. Scrambled PPNA was constructed with mismatches to three bases within the antisense PPNA1 sequence.

Results: PPNA1 and PPNA2 caused concentration-dependent growth inhibition and had bactericidal effects. The minimal bactericidal concentrations of antisense PPNA1 and PPNA2 were 30μmol/l and 40μmol/l, respectively. The scrambled PPNA had no effect on bacterial growth, even at higher concentrations, confirming the sequence specificity of the probes. RT-PCR showed that the antisense PPNAs suppressed ftsZ mRNA expression in a dose-dependent manner.

Conclusion: Our results demonstrate that the potent effects of PNAs on bacterial growth and cell viability were mediated by the down-regulation or even knock-out of ftsZ gene expression. This highlights the utility of ftsZ as a promising target for the development of new antisense antibacterial agents to treat MRSA infections.

Keywords: Antisense; Methicillin-resistant; Peptide nucleic acid; Staphylococcus aureus; ftsZ.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Anti-Bacterial Agents / chemistry
  • Anti-Bacterial Agents / pharmacology*
  • Bacterial Proteins / genetics*
  • Bacterial Proteins / metabolism
  • Cell-Penetrating Peptides
  • Cytoskeletal Proteins / genetics*
  • Cytoskeletal Proteins / metabolism
  • Down-Regulation
  • Gene Expression / drug effects
  • Methicillin-Resistant Staphylococcus aureus / drug effects*
  • Methicillin-Resistant Staphylococcus aureus / growth & development
  • Oligonucleotides, Antisense / pharmacology*
  • Peptide Nucleic Acids / pharmacology*

Substances

  • Anti-Bacterial Agents
  • Bacterial Proteins
  • Cell-Penetrating Peptides
  • Cytoskeletal Proteins
  • FtsZ protein, Bacteria
  • Oligonucleotides, Antisense
  • Peptide Nucleic Acids