Speaker
Description
The bacterial flagellum represents one of the most intricate macromolecular assemblies mediating bacterial motility, comprising approximately two dozen distinct proteins. Its architecture includes a rotary motor, a universal joint, and a helical external filament, the latter primarily constructed from flagellin subunits. The majority of flagellar protein subunits are translocated to the distal, growing end of the filament via the central channel by the flagellar Type III secretion system (fT3SS), located at the cytoplasmic face of the basal body. The fT3SS functions as a highly ordered nanomachine that exports these subunits in a temporally regulated manner. Experimental evidence demonstrates that secretion occurs at an extraordinary rate, on the order of several thousand amino acids per second. Here, we develop an injection–diffusion model that provides a theoretical framework consistent with the observed secretion and flagellar elongation rates. Moreover, we examine structural features of the fT3SS that may account for its exceptional efficiency, which exceeds that of other pore-based secretion systems.
