Pore Forming Activity of the Escherichia coli Type III Secretion System Protein EspD

摘要: Enterohemorrhagic Escherichia coli is a causative agent of gastrointestinal and diarrheal diseases. Pathogenesis associated with enterohemorrhagic E. involves direct delivery virulence factors from the bacteria into epithelial cell cytosol via syringe-like organelle known as type III secretion system. The system protein EspD critical factor required for formation translocation pore on host membrane. Here, we show that recombinant spontaneously integrates large unilamellar vesicle (LUV) lipid bilayers; however, incorporation anionic phospholipids such phosphatidylserine an acidic pH. Leakage assays performed fluorescent dextrans confirmed formed structure inner diameter ∼2.5 nm. Protease mapping indicated two transmembrane helical hairpin penetrated layer positioning N- C-terminal domains extralumenal surface LUVs. Finally, combination glutaraldehyde cross-linking rate zonal centrifugation suggested in LUV membranes forms ∼280–320-kDa oligomeric consisting ∼6–7 subunits.