The Coiled-coil Domain of EspA Is Essential for the Assembly of the Type III Secretion Translocon on the Surface of EnteropathogenicEscherichia coli

摘要: Enteropathogenic E. coli (EPEC) utilize a type III secretion system to deliver virulence-associated effector proteins the host cell. Four proteins, EspA, EspB, EspD, and Tir, which are integral formation of characteristic "attaching effacing" (A/E) intestinal lesions, known be exported via EPEC system. Recent work demonstrated that EspA is major component filamentous structure, elaborated on surface EPEC, required for translocation EspB Tir. The carboxyl terminus predicted comprise an alpha-helical region, demonstrates heptad periodicity whereby positions d in repeat unit abcdefg occupied by hydrophobic residues, indicating propensity coiled-coil interactions. Here we demonstrate multimeric isoforms culture supernatants EspA:EspA interaction solid phase. Non-conservative amino acid substitution specific residues generated mutants defective filament assembly but retained ability induce A/E lesions; additional mutation totally abolished lesion formation. These results similarity flagellar biosynthesis indicate domain filament-associated translocon.