Transcriptional profiling of M. tuberculosis CDC1551 wild type vs aprABC null, aprBC null, aprC null and phoP transposon mutants.. Mycobacterium tuberculosis

Following phagocytosis by macrophages, Mycobacterium tuberculosis (Mtb) senses the intracellular environment and remodels its gene expression for growth in the phagosome. Abramovitch et.al. in this current study identified an Acid and Phagosome Regulated (aprABC) locus that is unique to the Mtb complex and whose gene expression is induced during growth in acidic environments in vitro and in macrophages. The authors propose a model where phoP senses the acidic pH of the phagosome and induces aprABC expression to fine-tune processes unique for intracellular adaptation of Mtb complex bacteria. Overall design: This study uses microarray analyses to compare transcriptional responses of wild type Mycobacterium tuberculosis (CDC1551) to aprABC locus deletion mutants and the phoP transposon mutant. The bacteria were grown to early log phase in vented T-75 standing flasks containing 12 mL of pH 7.0 7H9 OADC medium. Transcript levels of the wild type bacteria were compared to the following mutants: aprABC null, aprBC null, aprC null, phoP::Tn mutant.