|
Many pathogenic and symbiotic gram-negative bacteria express a highly conserved type III secretion system (T3SS) involved in assembling a macromolecular needle complex that injects toxins into eukaryotic hosts.
 In a series of earlier papers, Timothy L. Yahr and colleagues characterized a cascade of interacting proteins that respond to secretory activity by boosting T3SS gene expression. In the current work, Yahr et al. reconstitute the regulatory cascade in vitro, using purified components, validating the genetic model for how T3SS gene expression is controlled. "This culmination of roughly five years of work shows that the regulatory cascade is the primary pathway involved in coupling transcription to secretory activity, a seemingly complex task. I find the elegance and simplicity of the system fascinating." The cascade's transcriptional activator, ExsA, is a member of the AraC family of more than 2,000 proteins, many of which regulate gene expression, says Yahr. AraC proteins might be targeted for therapeutics, and understanding their structure and function will be critical to these efforts. Only a handful of AraC proteins are known to be directly controlled by protein ligands, says Yahr. Yahr has determined for the first time the mechanics of one of these proteins-ExsD-and that may serve as a model for future studies of protein ligands that regulate other AraC proteins, says Yahr.
(E. D. Brutinel, C. A. Vakulskas, and T. L. Yahr. 2010. ExsD inhibits expression of the Pseudomonas aeruginosa type III secretion system by disrupting ExsA self-association and DNA binding activity. J. Bacteriol. 192:1479-1486.)
|
Journal Highlights 
Facebook
del.icio.us
Digg
Furl 
Yahoo!My Web
StumbleUpon
Google
Technorati 
reddit
Twitter
