Cytoskeleton-modulating effectors of enteropathogenic and enterohemorrhagic Escherichia coli: a case for EspB as an intrinsically less-ordered effector

Enterohemorrhagic and enteropathogenic Escherichia coli produce various effector proteins that are directly injected into the host-cell cytosol through the type III secretion system. E. coli secreted protein (Esp)B is one such effector protein, and affects host-cell morphology by reorganizing actin networks. Unlike most globular proteins that have well-ordered, rigid structures, the structures of type III secretion system effectors from pathogenic Gram-negative bacteria, including EspB, are often less well-ordered. This minireview focuses on the functional relationship between the structural properties of these proteins and their roles in type III secretion system-associated pathogenesis.