Brucella effector hijacks endoplasmic reticulum quality control machinery to prevent premature egress

Abstract

Perturbation of endoplasmic reticulum (ER) functions can have critical consequences for cellular homeostasis. An elaborate surveillance system known as ER quality control (ERQC) ensures that only correctly assembled proteins reach their destination. Persistence of misfolded or improperly matured proteins upregulates the unfolded protein response (UPR) to cope with stress, activates ER associated degradation (ERAD) for delivery to proteasomes for degradation. We have identified a Brucella abortus type IV secretion system effector called BspL that targets Herp, a key component of ERQC and is able to augment ERAD. Modulation of ERQC by BspL results in tight control of the kinetics of autophagic Brucella-containing vacuole formation, preventing premature bacterial egress from infected cells. This study highlights how bacterial pathogens may hijack ERAD components for fine regulation of their intracellular trafficking.