SKIP, the host target of the Salmonella virulence factor SifA, promotes kinesin-1 dependent vacuolar membrane exchanges

As the result of their adaptation to the host, intracellular pathogens have evolved mechanisms to usurp and take the control of eukaryotic processes. In the case of Salmonella, this is in part achieved through the cytoplasmic translocation of bacterial effectors capable of acting on the biology of infected cells. These bacterial effectors might have enzymatic activities or target eukaryotic proteins. We have identified two Salmonella effectors that target the plus- end directed microtubule motor kinesin-1. PipB2 is a Salmonella vacuole-specific cargo adaptor for kinesin-1 while SifA binds the host protein SKIP, which interacts with the microtubule motor. SKIP is a large multi-domain protein of unknown function. Our recent investigations show that SKIP regulates the positioning of late endosomal compartments in a microtubules and kinesin-1 dependent manner. Moreover they indicate that SKIP activates the microtubule motor both in the context of infected and non-infected cells. Here we review these recent results and propose a model for the Salmonella effector-mediated regulation of kinesin-1 activity.