Rab1b is recruited by the Coxiella burnetii replicative vacuole

CAMPOY EM, ZOPPINO FCM, AND COLOMBO MARÍA ISABEL.

Rosario Argentina

Congreso; XLII Reunión Anual de la Sociedad Argentina de Bioquímica y Biología Molecular (SAIB); 2006

SAIB

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