2P58: Structure Of The Yersinia Pestis Type Iii Secretion System Needle Protein Yscf In Complex With Its Chaperones Ysce/yscg

The plague-causing bacterium Yersinia pestis utilizes a type III secretion system to deliver effector proteins into mammalian cells where they interfere with signal transduction pathways that mediate phagocytosis and the inflammatory response. Effector proteins are injected through a hollow needle structure composed of the protein YscF. YscG and YscE act as "chaperones" to prevent premature polymerization of YscF in the cytosol of the bacterium prior to assembly of the needle. Here, we report the crystal structure of the YscEFG protein complex at 1.8 A resolution. Overall, the structure is similar to that of the analogous PscEFG complex from the Pseudomonas aeruginosa type III secretion system, but there are noteworthy differences. The structure confirms that, like PscG, YscG is a member of the tetratricopeptide repeat family of proteins. YscG binds tightly to the C-terminal half of YscF, implying that it is this region of YscF that controls its polymerization into the needle structure. YscE interacts with the N-terminal tetratricopeptide repeat motif of YscG but makes very little direct contact with YscF. Its function may be to stabilize the structure of YscG and/or to participate in recruiting the complex to the secretion apparatus. No electron density could be observed for the 49 N-terminal residues of YscF. This and additional evidence suggest that the N-terminus of YscF is disordered in the complex with YscE and YscG. As expected, conserved residues in the C-terminal half of YscF mediate important intra- and intermolecular interactions in the complex. Moreover, the phenotypes of some previously characterized mutations in the C-terminal half of YscF can be rationalized in terms of the structure of the heterotrimeric YscEFG complex.
PDB ID: 2P58Download
MMDB ID: 62803
PDB Deposition Date: 2007/3/14
Updated in MMDB: 2017/10
Experimental Method:
x-ray diffraction
Resolution: 1.8  Å
Source Organism:
Similar Structures:
Biological Unit for 2P58: trimeric; determined by author and by software (PISA)
Molecular Components in 2P58
Label Count Molecule
Proteins (3 molecules)
Putative Type III Secretion Protein Ysce
Molecule annotation
Putative Type III Secretion Protein Yscf
Molecule annotation
Putative Type III Secretion Protein Yscg
Molecule annotation
* Click molecule labels to explore molecular sequence information.

Citing MMDB