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

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

Marsella

Congreso; 5th international meeting on rickettsiae and ricketsial diseases; 2008

American Society of Rickettsiology

Coxiella burnetii is a Gram‐negative obligated intracellular bacterium. Afterinternalization, this bacterium replicates in a large parasitophorous vacuolethat has features of both phagolysosomes and autophagosomal compartments.We have previously demonstrated that early after internalization Coxiellaphagosomes interact with both the endocytic and autophagic pathways. In thisreport we present evidence that the Coxiella‐replicative vacuoles (CRV) alsointeract with the secretory pathway. Rab1b is a small GTPase responsible forthe anterograde transport between the Endoplasmic Reticulum and GolgiApparatus. We have evidence that Rab1b is recruited to the CRV and thatoverexpression of GFPRab1bwt or the active GTPase defective mutant(Q67L) affects the development of the Coxiella‐replicative compartment. Inthe present work we have examined the fusion competence of CRVs in cellsoverexpressing Rab1b Q67L. For this purpose Coxiella infected cells wereincubated with rodamine‐labeled heat inactivated Staphylococcus aureus orrodamine‐dextran, to label the phagocytic and endocytic pathways,respectively. Our results indicate that fusion between CRV and bothcompartments was hampered. These results suggest that the GTPase defectivemutant of Rab1b alters the normal development of the Coxiella vacuole bychanging the fusogenic capacity of this compartment.