Disease-causing bacteria often manipulate host cells in a way that helps the pathogen evade host immune responses. To facilitate this process, they produce molecules known as effector proteins that alter the host's cellular processes to the pathogens's advantage. Many pathogenic Gram-negative bacteria use complex secretion pathways - known as type III secretion systems - to inject effector proteins into host cells. In these pathways, chaperones direct effector proteins to a needle-like secretion apparatus, which then delivers the effector protein into the host cell. After entering the host cell, effector proteins modulate cell functions and may affect disease progression and severity.
The effector protein ExoU and its chaperone SpcU are components of the Pseudomonas aeruginosa type III secretion system. P. aeruginosa is a type of Gram-negative bacteria that commonly causes healthcare-associated infections and often affects people with cystic fibrosis. Pseudomonas infections are becoming increasingly difficult to treat due to drug resistance. Secretion of ExoU has been associated with more severe infections in both humans and animal models. Researchers from the Center for Structural Genomics of Infectious Diseases (CSGID) have determined the 1.92 Å X-ray structure of the ExoU–SpcU complex, the first structure of a full-length type III effector in complex with its full-length chaperone. Scientists may use the crystallographic data to better understand how ExoU kills host cells and to develop inhibitors of this potent toxin.
For more information, please see the Protein Data Bank entry 3TU3.
All featured structures from the NIAID Structural Genomics Centers
Last Updated May 09, 2012