Type Three Secretion

Type Three Secretion

Type three secretion involves the formation of a complex in bacteria which is used to inject various proteins into the host cell.

Locus of Enterocyte Effacement

A pathogenicity island which contains genes required for lesion formation:

Eae: intimin (25kDa) attaches to Tir

EspB (37kDa) and EspD (39kDa): form a pore complex in the host cell (needle tip)

Tir (90kDa): receptor which is translocated and inserted into host membrane

The Needle

Can reach up to 600nm in length.

EspA (25kDa) filament is a 5-stranded helix with ridges and troughs

The hollow central channel is smooth and is 25Angstroms in diameter.

Pierces the host cell.

Injects bacteria proteins into the host.