Extra! Extracellular Effector Delivery into Host Cells via the Type 3 Secretion System.

Area of Science:

• Microbiology
• Molecular Biology
• Pathogenesis

Background:

• The type three secretion system (T3SS) is a crucial virulence factor in many bacterial pathogens.
• T3SS facilitates the delivery of effector proteins into host cells, enabling pathogen manipulation of host functions.
• The conventional model involves effector translocation directly from within the T3SS into the host cell.

Purpose of the Study:

• To investigate an alternative mechanism of effector protein translocation mediated by the T3SS.
• To characterize the translocation pathway of the EspC effector from enteropathogenic Escherichia coli.

Main Methods:

• Utilized molecular genetics and cell biology techniques to study effector translocation.
• Investigated the interaction of EspC with the T3SS and its subsequent entry into host cells.

Main Results:

• Demonstrated that the EspC effector binds to the exterior of the T3SS.
• Showed that EspC gains access to the host cell cytoplasm via the T3SS pore.
• Identified a novel extracellular-initiated translocation mechanism for T3SS effectors.

Conclusions:

• The study reveals a previously unrecognized mechanism for bacterial effector delivery.
• This alternative translocation pathway, involving extracellular T3SS binding, is likely employed by other T3SS-utilizing pathogens.
• Findings expand our understanding of bacterial virulence strategies and T3SS function.