TccP2-mediated subversion of actin dynamics by EPEC 2 - a distinct evolutionary lineage of enteropathogenic Escherichia coli.

Enteropathogenic Escherichia coli (EPEC) is a major cause of infantile diarrhoea in developing countries. While colonizing the gut mucosa, EPEC triggers extensive actin-polymerization activity at the site of intimate bacterial attachment, which is mediated by avid interaction between the outer-membrane adhesin intimin and the type III secretion system (T3SS) effector Tir. The prevailing dogma is that actin polymerization by EPEC is achieved following tyrosine phosphorylation of Tir, recruitment of Nck and activation of neuronal Wiskott-Aldrich syndrome protein (N-WASP).

Interaction and localization studies of enteropathogenic Escherichia coli type IV bundle-forming pilus outer membrane components.

Typical enteropathogenic Escherichia coli strains express an established virulence factor belonging to the type IV pili family, called the bundle-forming pilus (BFP). BFP are present on the cell surface as bundled filamentous appendages, and are assembled and retracted by proteins encoded by the bfp operon. These proteins assemble to form a molecular machine.

The ATPase activity of BfpD is greatly enhanced by zinc and allosteric interactions with other Bfp proteins.

Type IV pilus biogenesis, protein secretion, DNA transfer, and filamentous phage morphogenesis systems are thought to possess similar architectures and mechanisms. These multiprotein complexes include members of the PulE superfamily of putative NTPases that have extensive sequence similarity and probably similar functions as the energizers of macromolecular transport. We purified the PulE homologue BfpD of the enteropathogenic Escherichia coli bundle-forming pilus (BFP) biogenesis machine and characterized its ATPase activity, providing new insights into its mode of action.

SepL, a protein required for enteropathogenic Escherichia coli type III translocation, interacts with secretion component SepD.

Enteropathogenic Escherichia coli (EPEC), an important cause of infantile diarrhoea in the developing world, disrupts host cell microvilli, causes actin rearrangements and attaches intimately to the host cell surface. This characteristic phenotype, referred to as the attaching and effacing (A/E) effect, is encoded on a 36 kb pathogenicity island called the locus of enterocyte effacement (LEE). The LEE includes genes involved in type III secretion and translocation, the eae gene encoding an outer membrane adhesin known as intimin, the tir gene for the translocated intimin receptor, a regulator and various genes of unknown function.

The inner membrane subassembly of the enteropathogenic Escherichia coli bundle-forming pilus machine.

Type IV pili (Tfps) are filamentous surface appendages expressed by Gram-negative microorganisms and play numerous roles in bacterial cell biology. Tfp biogenesis machineries are highly conserved and resemble protein secretion and DNA uptake systems. Although components of Tfp biogenesis systems have been identified, it is not known how they interact to form these machineries.