A New Component of the Type III Secretion System
Transport of effector proteins from bacterial pathogens into host cells is critical for pathogen virulence. In gram-negative bacteria, transport occurs through the specialized type III system. In this issue, Xiaofeng Zhou and colleagues identify VrpA of Xanthomonas species as a component of the type III secretion system localized to the periplasmic space, thus expanding mechanistic understanding of this important secretory process .