Coxiella burnetii effector CvpB modulates phosphoinositide metabolism for optimal vacuole development

Eric Martinez (1) , Julie Allombert (1) , Franck Cantet (1) , Anissa Lakhani (1) , Naresh Yandrapalli (1) , Aymeric Neyret (1) , Isobel Norville (1) , Cyril Favard (1) , Delphine Muriaux (2, 1) , Matteo Bonazzi (1)

1 CPBS - Centre d’études d’Agents Pathogènes et Biotechologies pour la Santé
2 Virologie humaine

The Q fever bacterium Coxiella burnetii replicates inside host cells within a large Coxiella-containing vacuole (CCV) whose biogenesis relies on the Dot/Icm-dependent secretion of bacterial effectors. Several membrane trafficking pathways contribute membranes, proteins, and lipids for CCV biogenesis. These include the endo-cytic and autophagy pathways, which are characterized by phos-phatidylinositol 3-phosphate [PI(3)P]-positive membranes. Here we show that the C. burnetii secreted effector Coxiella vacuolar protein B (CvpB) binds PI(3)P and phosphatidylserine (PS) on CCVs and early endosomal compartments and perturbs the activity of the phosphatidylinositol 5-kinase PIKfyve to manipulate PI(3)P metabolism. CvpB association to early endosome triggers vacuolation and clustering, leading to the channeling of large PI(3)P-positive membranes to CCVs for vacuole expansion. At CCVs, CvpB binding to early endosome-and autophagy-derived PI(3)P and the concom-itant inhibition of PIKfyve favor the association of the autophago-somal machinery to CCVs for optimal homotypic fusion of the Coxiella-containing compartments. The importance of manipulating PI(3)P metabolism is highlighted by mutations in cvpB resulting in a multivacuolar phenotype, rescuable by gene complementa-tion, indicative of a defect in CCV biogenesis. Using the insect model Galleria mellonella, we demonstrate the in vivo relevance of defective CCV biogenesis by highlighting an attenuated viru-lence phenotype associated with cvpB mutations.

Domaines: Bactériologie

Eric Martinez, Julie Allombert, Franck Cantet, Anissa Lakhani, Naresh Yandrapalli, et al.. Coxiella burnetii effector CvpB modulates phosphoinositide metabolism for optimal vacuole development. Proceedings of the National Academy of Sciences of the United States of America, 2016, 113 (23), pp.E3260-E3269. ⟨10.1073/pnas.1522811113⟩. ⟨hal-01999389⟩