Gene expression of Mycobacterium tuberculosis putative transcription factors whiB1-7 in redox environments

The seven WhiB proteins of Mycobacterium tuberculosis (M.tb) are widely believed to be redox-sensing transcription factors due to their binding of iron-sulfur clusters and similarities to DNA binding proteins. Here, we explored the nature of this hypothesized relationship. We exposed M.tb to physiologic conditions such as gradual hypoxia, nitric oxide (NO), cyclic AMP and in vivo conditions, and measured transcription of the whiB genes. We found whiB3 to be induced both by hypoxia and NO, whiB7 to be induced in macrophage-like cells, and whiB4 to be induced in mouse lung. Cyclic AMP induced whiB1,-2, -4, -6 and -7. Our data indicate that the M.tb whiB genes are induced independently by various stimuli which may add versatility to their suggested redox-sensing properties.