1K3S: Type Iii Secretion Chaperone Sige

Several Gram-negative bacterial pathogens have evolved a type III secretion system to deliver virulence effector proteins directly into eukaryotic cells, a process essential for disease. This specialized secretion process requires customized chaperones specific for particular effector proteins. The crystal structures of the enterohemorrhagic Escherichia coli O157:H7 Tir-specific chaperone CesT and the Salmonella enterica SigD-specific chaperone SigE reveal a common overall fold and formation of homodimers. Site-directed mutagenesis suggests that variable, delocalized hydrophobic surfaces observed on the chaperone homodimers are responsible for specific binding to a particular effector protein. Isothermal titration calorimetry studies of Tir-CesT and enzymatic activity profiles of SigD-SigE indicate that the effector proteins are not globally unfolded in the presence of their cognate chaperones.
PDB ID: 1K3SDownload
MMDB ID: 18062
PDB Deposition Date: 2001/10/3
Updated in MMDB: 2001/12
Experimental Method:
x-ray diffraction
Resolution: 1.9  Å
Source Organism:
Similar Structures:
Biological Unit for 1K3S: dimeric; determined by author and by software (PISA)
Molecular Components in 1K3S
Label Count Molecule
Proteins (2 molecules)
Sige(Gene symbol: pipC)
Molecule annotation
Chemical (1 molecule)
* Click molecule labels to explore molecular sequence information.

Citing MMDB