The role of Mycobacterium tuberculosis transcription factor Rv1985c in regulating adaptation to hypoxia and reaeration

Abstract

Mycobacterium tuberculosis is the deadliest infectious organism in the world, yet remains severely in need of updated treatment options, vaccine candidates, and improved diagnostic tools. This need derives from an incredibly complex host-pathogen interaction that has proved reticent to the identification of clear links between bacterial adaptation and host determinants of infection control. To better understand these links, we have developed a systematic method to evaluate the regulatory role of each transcription factor (TF) in Mycobacterium tuberculosis (MTB) during infection. We created a TF-induction library by cloning 207 of the estimated 214 MTB TFs into an anhydrotetracycline-inducible expression vector and transforming these into wildtype H37Rv. This library of mutants was screened through both macrophage infection and a hypoxia/reaeration time course – two critical contexts for the progression of infection. We identified 24 TFs that lead to defective growth in macrophages, as well as 5 TFs with a hypoxia/reaeration induction defect. One TF, Rv1985c, was investigated in further detail and revealed to drive a continued repression of a ribosomal protein locus during the accumulation of the growth defect over the course of reaeration. The regulons identified here could provide novel insight into the specific, evolved transcriptional adaptations required for MTB to cause disease.