2UWJ: Structure of the Heterotrimeric Complex Which Regulates Type III Secretion Needle Formation

Citation:
Abstract
Type III secretion systems (T3SS), found in several Gram-negative pathogens, are nanomachines involved in the transport of virulence effectors directly into the cytoplasm of target cells. T3SS are essentially composed of basal membrane-embedded ring-like structures and a hollow needle formed by a single polymerized protein. Within the bacterial cytoplasm, the T3SS needle protein requires two distinct chaperones for stabilization before its secretion, without which the entire T3SS is nonfunctional. The 2.0-A x-ray crystal structure of the PscE-PscF(55-85)-PscG heterotrimeric complex from Pseudomonas aeruginosa reveals that the C terminus of the needle protein PscF is engulfed within the hydrophobic groove of the tetratricopeptide-like molecule PscG, indicating that the macromolecular scaffold necessary to stabilize the T3SS needle is totally distinct from chaperoned complexes between pilus- or flagellum-forming molecules. Disruption of specific PscG-PscF interactions leads to impairment of bacterial cytotoxicity toward macrophages, indicating that this essential heterotrimer, which possesses homologs in a wide variety of pathogens, is a unique attractive target for the development of novel antibacterials.
PDB ID: 2UWJDownload
MMDB ID: 46796
PDB Deposition Date: 2007/3/22
Updated in MMDB: 2012/11 
Experimental Method:
x-ray diffraction
Resolution: 2  Å
Source Organism:
Similar Structures:
Biological Unit for 2UWJ: hexameric; determined by author and by software (PQS)
Molecular Components in 2UWJ
Label Count Molecule
Proteins (6 molecules)
2
Type III Export Protein Psce
Molecule annotation
2
Type III Export Protein Pscf
Molecule annotation
2
Type III Export Protein Pscg
Molecule annotation
Chemicals (6 molecules)
1
6
* Click molecule labels to explore molecular sequence information.

Citing MMDB
.