Project description:Guanidine DNA quadruplex (G4-DNA) structures convey a distinctive layer of epigenetic information that is critical for the regulation of key biological activities and processes as genome transcription regulation, replication and repair. Despite several works that have been published recently, the information regarding their role and possible use as therapeutic drug targets in bacteria is still scarce. Here, we tested the biological activity of a small G4-DNA ligand library based on the naphthalene diimide (NDI) pharmacophore, against both Gram-positive and Gram-negative bacteria. For the best compound identified, NDI-10, the action mechanism was further characterized. Gram-negative bacteria were more resistant altogether due to the presence of the outer membrane, although the activity of the G4-Ligand was generally bactericidal, while it was bacteriostatic for Gram-positive bacteria. This asymmetric activity could be related to the different prevalence of putative G4-DNA structures in each group, the influence that they can exert on the gene expression (which was found more severe for the Gram-negative bacteria) and the role of the G4 structures in these bacteria, that seems to be more related to promote transcription in Gram-positive bacteria and repress transcription in Gram-negative.
Project description:We profiled the expression of circulating microRNAs (miRNAs) in mice exposed to gram-positive and gram-negative bacteria using Illumina small RNA deep sequencing. Recombinant-specific gram-negative pathogen Escherichia coli (Xen14) and gram-positive pathogen Staphylococcus aureus (Xen29) were used to induce bacterial infection in mice at a concentration of 1 × 108 bacteria/100 μL of phosphate buffered saline (PBS). Small RNA libraries generated from the serum of mice after exposure to PBS, Xen14, Xen29, and Xen14+Xen29 via the routes of subcutaneous injection (I), cut wound (C), or under grafted skin (S) were analyzed using an Illumina HiSeq2000 Sequencer. Following exposure to gram-negative bacteria alone, no differentially expressed miRNA was found in the injection, cut, or skin graft models. Exposure to mixed bacteria induced a similar expression pattern of the circulating miRNAs to that induced by gram-positive bacterial infection. Upon gram-positive bacterial infection, 9 miRNAs (mir-193b-3p, mir-133a-1-3p, mir-133a-2-3p, mir-133a-1-5p, mir-133b-3p, mir-434-3p, mir-127-3p, mir-676-3p, mir-215-5p) showed upregulation greater than 4-fold with a p-value < 0.01. Among them, mir-193b-3p, mir-133a-1-3p, and mir-133a-2-3p presented the most common miRNA targets expressed in the mice exposed to gram-positive bacterial infection.