Structure of IDP95069

Crystal structure of type III effector protein ExoU (exoU)

Edit deposit information
CSGID target
IDP95069 
PDB Id
4QMK (NCBI MMDB
Authors
A.S.Halavaty,G.H.Tyson,A.Zhang,A.R.Hauser,W.F.Anderson,Center For Structural Genomics Of Infectious Diseases (Csgid) 
Responsible person
Andrei Halavaty 
Responsible lab
Northwestern University 
Deposition Date
Jun 16, 2014 
Release Date
Dec 17, 2014 

Annotation

Description
Bacterial toxins require localization to specific intracellular compartments following injection into host cells. In this study, we examine the membrane targeting of a broad family of bacterial proteins, the patatin-like phospholipases. The best-characterized member of this family is ExoU, an effector of the Pseudomonas aeruginosa type III secretion system. Upon injection into host cells, ExoU localizes to the plasma membrane, where it uses its phospholipase A2 activity to lyse infected cells. The targeting mechanism of ExoU is poorly characterized, but it was recently found to bind to the phospholipid phosphatidylinositol 4,5-bisphosphate (PI(4,5)P2), a marker for the plasma membrane of eukaryotic cells. We confirmed that the membrane localization domain (MLD) of ExoU had direct affinity for PI(4,5)P2 and determined that this binding was required for ExoU localization. Previously uncharacterized ExoU homologs from Pseudomonas fluorescens and Photorhabdus asymbiotica also localized to the plasma membrane and required PI(4,5)P2 for this localization. A conserved arginine within the MLD was critical for interaction of each protein with PI(4,5)P2 and for localization. Further, we determined the crystal structure of the full-length P. fluorescens ExoU and found that it was similar to that of P. aeruginosa ExoU. Each MLD contains a four-helical bundle, with the conserved arginine exposed at its cap to allow for interaction with the negatively charged PI(4,5)P2. Overall, these findings provide a structural explanation for the targeting of patatin-like phospholipases to the plasma membrane and define the MLD of ExoU as a member of a new class of PI(4,5)P2 binding domains. Published in (2015) J.Biol.Chem. 290: 2919-2937. 
Functional assignment
Type III effector protein 

Ligands

Ligand code Name Ligand type
175 3,5-dihydro-5-methylidene-4h-imidazol-4-on

Structure information

Unit cell parameters

Space Group
P 1 21 1  
Unit Cell

a=67.22Å, b=115.34Å, c=88.44Å
α=90.00, β=102.77, γ=90.00 
Solvent content
 
Matthews coefficient
 

Refinement

Data for the highest resolution shell is in parentheses.
Resolution range
29.86-2.50Å (2.56-2.50Å)  
Rall(%)
20.9 
Rwork(%)
20.6 (32.4) 
Rfree(%)
27.0 (42.1) 
Num. observed reflections
43205 (2480) 
Num. Rfree reflections
2203 (136) 
Completeness(%)
94.8 (74.0) 

Model parameters

Num Atoms
7951  
Num Waters
206  
Num Hetatoms
211  
Model mean isotropic B factor
56.690Å2  
RMSD bond length
0.014Å  
RMSD bond angle
1.609°  
Filename uploaded
4QMK.pdb (uploaded on Jan 12, 2015 11:14 AM)  
Inserted
Jan 12, 2015