EspM Is a Conserved Transcription Factor That Regulates Gene Expression in Response to the ESX-1 System
Kevin Sanchez, Micah J. Ferrell, Alexandra E. Chirakos, Kathleen R. Nicholson, Robert B. Abramovitch, Matthew M. Champion, Patricia A. Champion
Abstract
Mycobacterial pathogens use the ESX-1 system to transport protein substrates that mediate essential interactions with the host during infection. We previously demonstrated that in addition to transporting proteins, the ESX-1 secretion system regulates gene expression. Here, we identify a conserved transcription factor that regulates gene expression in response to the ESX-1 system. We demonstrate that this transcription factor is functionally conserved in M. marinum , a pathogen of ectothermic animals; M. tuberculosis , the human-pathogenic species that causes tuberculosis; and M. smegmatis , a nonpathogenic mycobacterial species. These findings provide the first mechanistic insight into how the ESX-1 system elicits a transcriptional response, a function of this protein transport system that was previously unknown.