Role of the Hrp Pilusin Type III Protein Secretion in Pseudomonas syringae

摘要

Bacterial surface appendages called pili and needle-like filaments are associated with protein and/or DNA transfer to recipient plant, human, or bacterial cells during pathogenesis or conjugation. Although it has long been suspected that pili function as a conduit for protein or DNA transfer, directive evidence has been lacking. The Hrp pilus of Pseudomonas syringae is assembled by the type III secretion system. We used an in situ immunogold labeling procedure to visu- alize the extrusion of an effector protein, AvrPto, from the tip of the Hrp pilus providing direct evidence that a bacterial pilus can function as a conduit for protein delivery.