Structure of the Mycobacterium tuberculosis type VII secretion system chaperone EspG(5) in complex with PE25-PPE41 dimer

The growth or virulence of Mycobacterium tuberculosis bacilli depends on homologous type VII secretion systems, ESX-1, ESX-3 and ESX-5, which export a number of protein effectors across membranes to the bacterial surface and environment. PE and PPE proteins represent two large families of highly polymorphic proteins that are secreted by these ESX systems. Recently, it was shown that these proteins require system-specific cytoplasmic chaperones for secretion. Here, we report the crystal structure of M. tuberculosisESX-5-secreted PE25-PPE41 heterodimer in complex with the cytoplasmic chaperone EspG