Total RNA was isolated from Mtb as described previously [109] with minor modifications. Briefly, logphase cells were pelleted, resuspended in TRIzol (Invitrogen), and transferred to Lysing Matrix B tube (QBiogene). The cells were lysed using MagNalyser (Roche), and RNA extracted with Trizol reagent as instructed by the manufacturer. RNA was treated with Turbo DNase (Ambion) for 30 minutes at 37°C twice and purified further using TRIzol solution and 100% Ethanol.