Bacterial macroscopic rope-like fibers with cytopathic and adhesive properties.

J Biol Chem 285(42):32336-32342 (2010) PMID 20688909 PMCID PMC2952234

We present a body of ultrastructural, biochemical, and genetic evidence that demonstrates the oligomerization of virulence-associated autotransporter proteins EspC or EspP produced by deadly human pathogens enterohemorrhagic (EHEC) and enteropathogenic (EPEC) Escherichia coli into novel macroscopic rope-like structures. The rope-like structures showed high aggregation and insolubility, stability to anionic detergents and high temperature, and binding to Congo Red and Thioflavin T dyes. These are properties also exhibited by human amyloidogenic proteins. These macroscopic ropes were not observed in cultures of non-pathogenic E. coli or isogenic espP or espC deletion mutants of EHEC or EPEC but were produced by an E. coli K-12 strain carrying a plasmid expressing espP. Purified recombinant EspP monomers were able to self-assemble into macroscopic ropes upon incubation suggesting that no other protein was required for assembly.The ropes bound to and showed cytopathic effects on cultured epithelial cells, served as a substratum for bacterial adherence and biofilm formation, and protected bacteria from antimicrobial compounds. We hypothesize that these ropes play a biologically significant role in the survival and pathogenic scheme of these organisms.