Coxiella burnetii effector CvpE maintains biogenesis of Coxiella-containing vacuoles by suppressing lysosome tubulation through binding PI(3)P and perturbing PIKfyve activity on lysosomes

ABSTRACT

Coxiella burnetii (C. burnetii) is the causative agent of Q fever, a zoonotic disease. Intracellular replication of C. burnetii requires the maturation of a phagolysosome-like compartment known as the replication permissive Coxiella-containing vacuole (CCV). Effector proteins secreted by the Dot/Icm secretion system are indispensable for maturation of a single large CCV by facilitating the fusion of promiscuous vesicles. However, the mechanisms of CCV maintenance and evasion of host cell clearance remain to be defined. Here, we show that C. burnetii secreted Coxiella vacuolar protein E (CvpE) contributes to CCV biogenesis by inducing lysosome-like vacuole (LLV) enlargement. LLV fission by tubulation and autolysosome degradation is impaired in CvpE-expressing cells. Subsequently, we found that CvpE suppresses lysosomal Ca²⁺ channel transient receptor potential channel mucolipin 1 (TRPML1) activity in an indirect manner, in which CvpE binds phosphatidylinositol 3-phosphate [PI(3)P] and perturbs PIKfyve activity in lysosomes. Finally, the agonist of TRPML1, ML-SA5, inhibits CCV biogenesis and C. burnetii replication. These results provide insight into the mechanisms of CCV maintenance by CvpE and suggest that the agonist of TRPML1 can be a novel potential treatment that does not rely on antibiotics for Q fever by enhancing Coxiella-containing vacuoles (CCVs) fission.

KEYWORDS:

• Coxiella burnetii
• effector proteins
• Coxiella-containing vacuoles
• lysosomes
• Coxiella vacuolar protein E

Acknowledgements

We thank Lei Song for providing several phosphoinositide-binding probe plasmids.

Disclosure statement

We declare that this research was conducted in the absence of any commercial or financial relationships that could be construed as potential conflicts of interest.

Author contributions

M.Z. and X.X. designed and conceived the experiments, conducted the data analysis, and wrote and revised the manuscript. M.Z. performed experiments. S.Z., W.W., C.Z., N.L., and R.C. contributed to and shared the experimental materials, reagents, and instruments. Y.Y. and X.O. conducted the formal analyses. B.W., J.J. and X.X. revised and edited the manuscript. All authors have read and agreed to the published version of the manuscript.

Data Availability statement

The authors confirmed that all data supporting the findings of this study are available within the article.

Additional information

Funding

This work was supported by grants from the National Natural Science Foundation of China (no. 31970178).