Sandbox Reserved 1075

EspG secretion is key in understanding the virulence of mycobacterium tuberculosis. The specificity of EspG binding affinity to its specific PE-PPE ligand have many contributing factors. The four different EspG proteins found in mycobacterium tuberculosis have different characteristics that influence binding, where EspG5 binds to the most PE-PPE proteins. Here EspG5 binds to PE25-PPE41 to be excreted in the ESAT-6 pathway.

You may include any references to papers as in: the use of JSmol in Proteopedia ^[1] or to the article describing Jmol ^[2] to the rescue.

Figure Legend

Function

a;lksdja;lskdjfa;lsdkfjas;ldkfja;sldkfj

Excretion

EspG PE-PPE excretion is done through the ESX secretion pathway.

Binding

Factors that influence binding of EspG and PE-PPE: Electrostatics: There is a partially negative over all charge on the EspG5 protein.

shape

ligand random coil key catalytic residues

Pocket Residues

Jon

Structural highlights

This is a sample scene created with SAT to by Group, and another to make of the protein. You can make your own scenes on SAT starting from scratch or loading and editing one of these sample scenes.

Relevance

Publication Abstract from PubMed

Nearly 10% of the coding capacity of the Mycobacterium tuberculosis genome is devoted to two highly expanded and enigmatic protein families called PE and PPE, some of which are important virulence/immunogenicity factors and are secreted during infection via a unique alternative secretory system termed "type VII." How PE-PPE proteins function during infection and how they are translocated to the bacterial surface through the five distinct type VII secretion systems [ESAT-6 secretion system (ESX)] of M. tuberculosis is poorly understood. Here, we report the crystal structure of a PE-PPE heterodimer bound to ESX secretion-associated protein G (EspG), which adopts a novel fold. This PE-PPE-EspG complex, along with structures of two additional EspGs, suggests that EspG acts as an adaptor that recognizes specific PE-PPE protein complexes via extensive interactions with PPE domains, and delivers them to ESX machinery for secretion. Surprisingly, secretion of most PE-PPE proteins in M. tuberculosis is likely mediated by EspG from the ESX-5 system, underscoring the importance of ESX-5 in mycobacterial pathogenesis. Moreover, our results indicate that PE-PPE domains function as cis-acting targeting sequences that are read out by EspGs, revealing the molecular specificity for secretion through distinct ESX pathways.

Structure of a PE-PPE-EspG complex from Mycobacterium tuberculosis reveals molecular specificity of ESX protein secretion.,Ekiert DC, Cox JS Proc Natl Acad Sci U S A. 2014 Oct 14;111(41):14758-63. doi:, 10.1073/pnas.1409345111. Epub 2014 Oct 1. PMID:25275011^[3]

From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine.