A novel EspA-associated surface organelle of enteropathogenic Escherichia coli involved in protein translocation into epithelial cells

Enteropathogenic Escherichia coli (EPEC), like among bacterial pathogens, employ a type WI secretion system to deliver effector proteins across the bacterial cell, In EPEC, four proteins are known to be exported by a type III secretion system-EspA, EspB and EspD required for subversion of host sell signal transduction pathways and a translocated intimin receptor (Tir) protein (formerly Hp90) which is tyrosine-phosphorylated following transfer to the host cell to become a receptor for intimin-mediated intimate attachment and 'attaching and effacing' (A/E) lesion formation, The structural basis for protein translocation has yet to Pre fully elucidated for any type III secretion system. Here, we describe a novel EspA-confirming filamentous organelle that is present on the bacterial surface during the early stage of A/E lesion formation, forms a physical bridge between the bacterium and the infected eukaryotic cell surface and is required for the translocation of EspB into infected epithelial cells.