In addition, the presence of diverse T7SSs in the Mpg genome, including an intact ESX-1, may suggest the feasibility of Mpg as a novel tuberculosis vaccine.
We show that MMAR_2894 is secreted by the ESX-1 system in <i>M. marinum</i> and is itself required for the optimal secretion of the known ESX-1 substrates in <i>M. marinum</i> Moreover, we found that MMAR_2894 was differentially required for hemolysis and cytolysis of macrophages, two lytic activities ascribed to the <i>M. marinum</i> ESX-1 system.<b>IMPORTANCE</b> Both <i>Mycobacterium tuberculosis</i>, the cause of human tuberculosis (TB), and <i>Mycobacterium marinum</i>, a pathogen of ectotherms, use the ESX-1 secretion system to cause disease.
EspI, the ESX-1 secretion-associated protein in Mycobacterium tuberculosis (MtEspI), is involved in repressing the activity of ESX-1-mediated secretion when the cellular ATP level is low.
Notably, only infection with a virulent strain, but not with attenuated ESX-1-defective strains, such as Bacillus Calmette-Guerin and live-attenuated M. tuberculosis vaccine strain MTBVAC, induced Bim upregulation and apoptosis, probably implicating virulence factor early secreted antigenic target 6-kDa protein in this process.
The EspA protein of Mycobacterium tuberculosis is essential for the type VII ESX-1 protein secretion apparatus, which delivers the principal virulence factors ESAT-6 and CFP-10.
The ESX-1 secretion system and its substrate ESAT-6 are required for M. tuberculosis to induce necrosis, but host factors that mediate the ESAT-6-promoted necrosis remain unknown.