FIG 6.

EspM regulates gene expression in response to the ESX-1 system. A model proposing a role for EspM in regulating whiB6 gene expression is shown. In the absence of the ESX-1 membrane complex, we propose that EspM represses whiB6 gene expression (highly repressed state). Reduced WhiB6 levels cause reduced activation of ESX-1 substrate gene expression, preventing substrate accumulation. In the presence of ESX-1, EspM still promotes repression of whiB6 gene expression, fine-tuning expression of the esx-1 substrate genes (repressed state). In the absence of espM, the levels of whiB6 and esx-1 substrate gene expression are derepressed.