The early secretory pathway contributes to the development of the Coxiella-replicative niche.

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

Mar del plata

Congreso; Reunion SAIB XLIII; 2007

Coxiella burnetii is a Gram-negative obligated intracellular bacterium. Afterinternalization, this bacterium replicates in a large parasitophorous vacuolethat has features of both phagolysosomes and autophagosomalcompartments. We have previously demonstrated that early afterinternalization Coxiella phagosomes interact with both the endocytic andautophagic pathways. In this report we present evidence that the Coxiellareplicativevacuoles (CRV) also interact with the secretory pathway. Rab1bis a small GTPase responsible for the anterograde transport between theEndoplasmic Reticulum and Golgi Apparatus. We have evidence that Rab1bis recruited to the CRV and that overexpression of GFP-Rab1bwt or theactive GTPase defective mutant (Q67L) affects the development of theCoxiella-replicative compartment. In the present work we have examinedthe fusion competence of CRVs in cells overexpressing Rab1b Q67L. For thispurpose Coxiella infected cells were incubated with rodamine-labeled heatinactivated Staphylococcus aureus or rodamine-dextran, to label thephagocytic and endocytic pathways, respectively. Our results indicate thatfusion between CRV and both compartments was hampered.These results suggest that the GTPase defective mutant of Rab1b alters thenormal development of the Coxiella vacuole by changing the fusogeniccapacity of this compartment.