A variety of microbes manipulate the cytoskeleton of mammalian cells to
promote their internalization, motility and⁄or spread. Among such bacte-ria, enteropathogenic Escherichia coliand enterohemorrhagic Escherichia
coliare closely related pathogens that adhere to human intestinal cells and
reorganize the underlying actin cytoskeleton into ‘pedestals’.
EspB is a multifunctional protein associated with the type III secretion
system of enterohaemorrhagic Escherichia coli, and interacts with various
biomolecules includinga-catenin in the host cell. The binding of EspB to
a-catenin is thought be involved in actin reorganization during bacterial
infection, although the precise mechanism of this phenomenon is still
The structural properties of EspB, a virulence factor of theEscherichia coli
O157 type III secretion system, were characterized. Far-UV and near-UV
CD spectra, recorded between pH 1.0 and pH 7.0, show that the protein
assumesa-helical structures and that some tyrosine tertiary contacts may
exist. All tyrosine side-chains are exposed to water, as determined by acryl-amide fluorescence quenching spectroscopy.