RNAseq of Staphylococcus aureus wildtype and two-Cys-type TetR repressor GbaA deletion mutant under nonstress condition

To investigate the changes in gene expression of Staphylococcus aureus COL and the gbaA deletion mutant under nonstress condition, strains were cultivated in RPMI1640 medium (Lonza) under vigorous agitation at 37°C in triplicate until cells have reached an optical density at 500?nm of 0.5. S. aureus cells were harvested and disrupted in 3 mM EDTA/ 200 mM NaCl lysis buffer with a Precellys24 Ribolyzer. RNA isolation was performed using the phenol-chloroform-isoamylalcohol approach. After precipitation with 3 M sodium acetate and isopropanol, the total RNA was washed with cold ethanol and the pellet was solved in sterile water. Initially RNA quality was checked by Trinean Xpose (Gentbrugge,Belgium) and Agilent RNA Nano 6000 kit on Agilent 2100 Bioanalyzer (Agilent Technologies, Böblingen, Germany). Samples contaminated with DNA were treated with DNase (Qiagen), cleaned as described above and rechecked by Xpose and Agilent Bioanalyzer. Finally RNA was free of DNA with an RNA Integrity Number (RIN) > 9 and rRNA Ratio [23s / 16s] > 1.5. Ribo-Zero rRNA Removal Kit (Bacteria) from Illumina (San Diego, CA, USA) was used to remove the ribosomal RNA molecules from the isolated total RNA. Removal of rRNA was checked by Agilent RNA Pico 6000 kit on Agilent 2100 Bioanalyzer (Agilent Technologies, Böblingen, Germany). RNA was free of detectable rRNA. TruSeq Stranded mRNA Library Prep Kit from Illumina (San Diego, CA, USA) was used to prepare cDNA libraries. The resulting cDNAs were sequenced paired end on an Illumina HiSeq 1500 system (San Diego, CA, USA) using 70 bp read length.