DSPE

DspE is a gene encoding a type III secretion system (T3SS) effector protein found in several plant-pathogenic bacteria, notably Erwinia chrysanthemi (Dickeya) and Pseudomonas syringae. In the literature, dspE is often discussed as part of the AvrE/DspE family, with DspE representing the Erwinia homolog and AvrE the Pseudomonas counterpart. The dspE gene is typically located within hrp/hrc pathogenicity islands that encode the T3SS machinery and its effector repertoire.

As a type III effector, DspE/AvrE proteins are translocated from the bacterial cell into plant host cells where they modulate host cellular processes to promote disease. They are implicated in altering endomembrane trafficking and membrane integrity, contributing to tissue maceration and necrosis in susceptible hosts. The exact molecular targets can vary by host species, and in some plant systems, AvrE/DspE proteins can be recognized by plant resistance genes, triggering effector-triggered immunity and a hypersensitive response.

Regulation of dspE expression is coordinated with other T3SS genes and is often induced under plant-mimicking conditions that activate the hrp/hrc regulatory network. Functional analyses show that loss of dspE reduces virulence in multiple hosts, supporting its role as a virulence determinant. The DspE/AvrE family is characterized by large effector proteins lacking obvious enzymatic domains, with their activities largely defined by interactions within the host cell.