To survive, Yersinia pestis must disarm caspase-1. Until the present study, bacterial molecules that directly modulate the inflammasome had not yet been reported. LaRock and Cookson were able to identify a leucine-rich protein secreted by Yersinia pestis that binds and disables its arch-enemy, the caspase-1 enzyme.
The potent substance, called Yop M, preempts the activity of caspase-1 and sequesters the enzyme to arrest the development of the inflammasome. As a consequence, the cell fails to sacrifice itself to get rid of the Yersinia and to warn other disease-fighting cells of the infection.
According to the researchers, the Yop M-mediated inhibition of caspase-1 is required for Yersinia to subvert immune signaling, delay inflammation and provoke severe illness. Its dual mechanism for blocking inflammatory cell death, by blocking enzymatic activity and inflammasome maturation, is distinctive.
While caspase-1 is helpful in combating a number of other microbial infections, several researchers have reported it to be harmful when its activation is aberrant or poorly controlled. Faulty caspase-1 regulation is implicated in several inflammatory disorders. Learning how pathogens manage caspase-1 to their advantage may suggest treatments to limiting its excess activity.
|Contact: Leila Gray|
University of Washington