Transcriptomics of Mycobacterium tuberculosis exposed to zinc limitation, zinc depletion by calprotectin and TPEN, and zinc toxicity

The purpose of this study was to determine the transcriptomes of Mycobacterium tuberculosis m2 6206 (Mtb) exposed to varying concentration of zinc (Zn2+) in vitro that mimic the concentrations of Zn2+ experienced in vivo during infection. Mtb were grown in the chemically defined Sauton's medium without Zn2+ added until expression of Zur-regulated genes were observed, indicating the onset of Zn-limitation. Cells were then treated with with different concentrations of Zn2+ through addition of 500 uM Zn2+, 6uM Zn2+, no added Zn2+, 0.35 mg/mL recombinant calprotectin (CP) or 0.8 µM N,N,N′,N′-tetrakis(2-pyridinylmethyl)-1,2-ethanediamine (TPEN). After 24 hours of exposure to the different [Zn2+] conditions, RNA was harvested, prepared for RNA-seq, and sequenced on the Illumina HiSeq platform with a paired-end (2x150bp) configuration. Transcriptomes of Mtb exposed to 500 μM Zn2+, 6 μM Zn2+, no added Zn2+, 0.35mg/mL recombinant calprotectin (CP), and 0.8 μM TPEN