Rab1b is recruited by the Coxiella burnetii replicative vacuole

CAMPOY, EMANUEL MARTIN; ZOPPINO, FELIPE CARLOS; COLOMBO MARIA ISABEL

Rosario

Congreso; Reunion SAIB XLIII; 2006

SAIB

Coxiella burnetii, the ethiological agent of Q fever, is a Gram-negativeobligated intracellular bacterium. Once inside the cell, this bacteriumreplicates in a large parasitophorous vacuole that shares characteristic ofphagolysosome-autophagolysosomal compartment. We have previouslydemonstrated that the activation of the autophagic pathway increases theinfection with C. burnetii. Rab1b is a small GTPase responsible for theanterograde transport between Endoplasmic Reticulum and Golgi Apparatus.We have evidence that Rab1b is involved in autophagosome formation. Inthe present work, CHO cells overexpressing GFP-Rab1bwt or the activeGTPase defective mutant were infected with C. burnetii for different periodsof time. Using confocal microscopy, we observed that at early times afterinfection no colocalization with this Rab protein was detected. In contrast,at later times after infection (i.e. 24-48h) the large replicative vacuoleswere decorated by Rab1b, in particularly by the active mutant. Theseresults suggest that membranes from the early secretory pathwaycontribute to the development of the Coxiella-replicative compartment.