2X9C: Crystal Structure Of A Soluble Prgi Mutant From Salmonella Typhimurium

Pathogenic Gram-negative bacteria use a type three secretion system (TTSS) to deliver virulence factors into host cells. Although the order in which proteins incorporate into the growing TTSS is well described, the underlying assembly mechanisms are still unclear. Here we show that the TTSS needle protomer refolds spontaneously to extend the needle from the distal end. We developed a functional mutant of the needle protomer from Shigella flexneri and Salmonella typhimurium to study its assembly in vitro. We show that the protomer partially refolds from alpha-helix into beta-strand conformation to form the TTSS needle. Reconstitution experiments show that needle growth does not require ATP. Thus, like the structurally related flagellar systems, the needle elongates by subunit polymerization at the distal end but requires protomer refolding. Our studies provide a starting point to understand the molecular assembly mechanisms and the structure of the TTSS at atomic level.
PDB ID: 2X9CDownload
MMDB ID: 82717
PDB Deposition Date: 2010/3/15
Updated in MMDB: 2011/10
Experimental Method:
x-ray diffraction
Resolution: 2.45  Å
Source Organism:
Similar Structures:
Biological Unit for 2X9C: monomeric; determined by author and by software (PISA)
Molecular Components in 2X9C
Label Count Molecule
Protein (1 molecule)
Protein Prgi(Gene symbol: prgI)
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB