New Method for Monitoring the Bacterial Type III Secretion System

Researchers have described a method for monitoring the type III secretion system used by pathogenic bacteria to inject virulence factors or toxins into host cells. The type III secretion system actively injects proteins into the cytosol of eukaryotic cells, where the translocated proteins facilitate bacterial pathogenesis by specifically interfering with host cell signal transduction and other cellular processes.

Investigators at the Hebrew University of Jerusalem (Israel) designed a real-time, high-throughput translocation assay that utilized fusions of effector genes to the â-lactamase reporter gene, positioned under the effector's native promoter and chromosomal location. Using this assay, they simultaneously and quantitatively analyzed the translocation kinetics of six core enteropathogenic Escherichia coli effectors, EspF, EspG, EspH, EspZ, Map, and Tir.

Results published in the February 14, 2008, issue of the journal Cell Host and Microbe revealed that translocation efficiency was determined by multiple factors, including the intrabacterial effector concentration, effector-chaperone interactions, the efficiency of bacterial attachment to the host cells, and by a translocation autoinhibition mechanism.

Insights gained during this study about the properties of the secretion system might be used to develop drugs designed to inhibit secretion activity and thereby prevent disease and infection.


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Hebrew University of Jerusalem