Specific chaperones for the type VII protein secretion pathway.

Mycobacteria use the dedicated type VII protein secretion systems ESX-1 and ESX-5 to secrete virulence factors across their highly hydrophobic cell envelope. The substrates of these systems include the large mycobacterial PE and PPE protein families, which are named after their characteristic Pro-Glu and Pro-Pro-Glu motifs. Pathogenic mycobacteria secrete large numbers of PE/PPE proteins via the major export pathway, ESX-5.

General secretion signal for the mycobacterial type VII secretion pathway.

Mycobacterial pathogens use specialized type VII secretion (T7S) systems to transport crucial virulence factors across their unusual cell envelope into infected host cells. These virulence factors lack classical secretion signals and the mechanism of substrate recognition is not well understood. Here we demonstrate that the model T7S substrates PE25/PPE41, which form a heterodimer, are targeted to the T7S pathway ESX-5 by a signal located in the C terminus of PE25.

Functional dissection of the PE domain responsible for translocation of PE_PGRS33 across the mycobacterial cell wall.

PE are peculiar exported mycobacterial proteins over-represented in pathogenic mycobacterial species. They are characterized by an N-terminal domain of about 110 amino acids (PE domain) which has been demonstrated to be responsible for their export and localization. In this paper, we characterize the PE domain of PE_PGRS33 (PE(Rv1818c)), one of the best characterized PE proteins.

Conserved Pro-Glu (PE) and Pro-Pro-Glu (PPE) protein domains target LipY lipases of pathogenic mycobacteria to the cell surface via the ESX-5 pathway.

The type VII secretion system ESX-5 is a major pathway for export of PE and PPE proteins in pathogenic mycobacteria. These mycobacteria-specific protein families are characterized by conserved N-terminal domains of 100 and 180 amino acids, which contain the proline-glutamic acid (PE) and proline-proline-glutamic acid (PPE) motifs after which they are named. Here we investigated secretion of the triacylglycerol lipase LipY, which in fast-growing mycobacteria contains a signal sequence, but in slow-growing species appears to have replaced the signal peptide with a PE or PPE domain.

Expression of copA and cusA in Shewanella during copper stress.

Copper homeostasis is tightly regulated in all living cells as a result of the necessity and toxicity of this metal in free cationic form. In Gram-negative bacteria CPx-type ATPases (e.g.