Coxiella burnetii localizes in a Rab7-labeled compartment with autophagic characteristics

WALTER BERON,; G GUTIERREZ, MAXIMILIANO; RABINOVITCH, M; COLOMBO, MARÍA I

INFECTION AND IMMUNITY

Año: 2002 vol. 70 p. 5816 - 5821

0019-9567

The obligate intracellular bacterium Coxiella burnetii, the agent of Q fever in Man and of coxiellosis in other animals, survives and replicates within large, acidified, phagolysosome-like vacuoles known to fuse homo- and heterotypically with other vesicles. In order to further characterize these vacuoles, HeLa cells were infected with C. burnetii phase II; 48 h later, bacteria-containing vacuoles were labeled by LysoTracker -a marker of acidic compartments-, accumulated monodansylcadaverine and displayed the protein LC3, both markers of autophagic vacuoles. Furthermore, 3-methyladenine or wortmannin, agents known to inhibit early stages in the autophagic process, blocked Coxiella vacuole formation. These autophagosomal features suggest that Coxiella vacuoles interact with the autophagic pathway. The localization and role of wild type and mutated Rab5 and Rab7, markers of early and late endosomes, respectively, were also examined to determine the role of these small GTPases in the trafficking of C. burnetii phase II. GFP-Rab5 and GFP-Rab7 constructs were overexpressed and visualized by fluorescence microscopy. Coxiella-containing large vacuoles were labeled with Rab7wt and with the GTPase deficient mutant Rab7Q67L whereas no colocalization was observed with the negative mutant Rab7T22N. The vacuoles were also decorated by GFP-Rab5Q79L, but not by GFP-Rab5wt. These results suggest that Rab7 participates in the biogenesis of the parasitophorous vacuoles.