Type III Secretion System (T3SS)

The Type III secretion system (T3SS), also known as the injectisome, is a specialized protein export apparatus found in many Gram-negative bacteria. It functions as a molecular syringe, enabling these bacteria to inject effector proteins directly from their cytoplasm into the cytoplasm of eukaryotic host cells. This direct translocation bypasses the extracellular environment and is a key mechanism for bacterial virulence and colonization. T3SS is a multi-component nanomachine composed of a basal body, export apparatus, needle filament, sorting platform, and translocation pore. Effector proteins manipulate host cell processes such as actin cytoskeleton rearrangement, cellular trafficking, apoptosis, and immune responses. Because T3SSs are essential for infection progression but absent from humans, they represent attractive targets for antivirulence therapies.

Other names

InjectisomeTTSS

Inhibition of T3SS assembly or function prevents effector protein translocation and reduces bacterial virulence.