The loss of the PDIM/PGL virulence lipids causes differential secretion of ESX-1 substrates in .

The mycobacterial cell envelope is a major virulence determinant in pathogenic mycobacteria. Specific outer lipids play roles in pathogenesis, modulating the immune system and promoting the secretion of virulence factors. ESX-1 (ESAT-6 system-1) is a conserved protein secretion system required for mycobacterial pathogenesis.

The antagonistic transcription factors, EspM and EspN, regulate the ESX-1 secretion system in .

Bacterial pathogens use protein secretion systems to transport virulence factors and regulate gene expression. Among pathogenic mycobacteria, including and , the ESAT-6 system 1 (ESX-1) secretion is crucial for host interaction. Secretion of protein substrates by the ESX-1 secretion system disrupts phagosomes, allowing mycobacteria cytoplasmic access during macrophage infections.

The loss of the PDIM/PGL virulence lipids causes differential secretion of ESX-1 substrates in .

The mycobacterial cell envelope is a major virulence determinant in pathogenic mycobacteria. Specific outer lipids play roles in pathogenesis, modulating the immune system and promoting the secretion of virulence factors. ESX-1 (ESAT-6 system-1) is a conserved protein secretion system required for mycobacterial pathogenesis (1, 2).

The EspN transcription factor is an infection-dependent regulator of the ESX-1 system in .

Unlabelled: Bacterial pathogens use protein secretion systems to translocate virulence factors into the host and to control bacterial gene expression. The ESX-1 (ESAT-6 system 1) secretion system facilitates disruption of the macrophage phagosome during infection, enabling access to the cytoplasm, and regulates widespread gene expression in the mycobacterial cell. The transcription factors contributing to the ESX-1 transcriptional network during mycobacterial infection are not known.

Functional Analysis of EspM, an ESX-1-Associated Transcription Factor in Mycobacterium marinum.

Pathogenic mycobacteria use the ESX-1 secretion system to escape the macrophage phagosome and survive infection. We demonstrated that the ESX-1 system is regulated by feedback control in Mycobacterium marinum, a nontuberculous pathogen and model for the human pathogen Mycobacterium tuberculosis. In the presence of a functional ESX-1 system, the WhiB6 transcription factor upregulates expression of ESX-1 substrate genes.

The genetic proteome: Using genetics to inform the proteome of mycobacterial pathogens.

Mycobacterial pathogens pose a sustained threat to human health. There is a critical need for new diagnostics, therapeutics, and vaccines targeting both tuberculous and nontuberculous mycobacterial species. Understanding the basic mechanisms used by diverse mycobacterial species to cause disease will facilitate efforts to design new approaches toward detection, treatment, and prevention of mycobacterial disease.

Conserved ESX-1 Substrates EspE and EspF Are Virulence Factors That Regulate Gene Expression.

, the cause of human tuberculosis, and , a nontubercular pathogen with a broad host range, require the ESX-1 secretion system for virulence. The ESX-1 system secretes proteins which cause phagosomal lysis within the macrophage via an unknown mechanism. As reported elsewhere (R.

Trypanosoma brucei Pex13.2 Is an Accessory Peroxin That Functions in the Import of Peroxisome Targeting Sequence Type 2 Proteins and Localizes to Subdomains of the Glycosome.

Kinetoplastid parasites, including , , and , harbor unique organelles known as glycosomes, which are evolutionarily related to peroxisomes. Glycosome/peroxisome biogenesis is mediated by proteins called peroxins that facilitate organelle formation, proliferation, and degradation and import of proteins housed therein. Import of matrix proteins occurs via one of two pathways that are dictated by their peroxisome targeting sequence (PTS).

EspM Is a Conserved Transcription Factor That Regulates Gene Expression in Response to the ESX-1 System.

Pathogenic mycobacteria encounter multiple environments during macrophage infection. Temporally, the bacteria are engulfed into the phagosome, lyse the phagosomal membrane, and interact with the cytosol before spreading to another cell. Virulence factors secreted by the mycobacterial ESX-1 (ESAT-6-system-1) secretion system mediate the essential transition from the phagosome to the cytosol.

A New ESX-1 Substrate in Mycobacterium marinum That Is Required for Hemolysis but Not Host Cell Lysis.

The ESX-1 (ESAT-6 system 1) secretion system plays a conserved role in the virulence of diverse mycobacterial pathogens, including the human pathogen and , an environmental mycobacterial species. The ESX-1 system promotes the secretion of protein virulence factors to the extracytoplasmic environment. The secretion of these proteins triggers the host response by lysing the phagosome during macrophage infection.

Esx Paralogs Are Functionally Equivalent to ESX-1 Proteins but Are Dispensable for Virulence in Mycobacterium marinum.

is a nontuberculous pathogen of poikilothermic fish and an opportunistic human pathogen. Like tuberculous mycobacteria, the M strain requires the ESX-1 (ESAT-6 system 1) secretion system for virulence in host cells. EsxB and EsxA, two major virulence factors exported by the ESX-1 system, are encoded by the genes within the ESX-1 locus.