Ehrlichia secretes Etf-1 to induce autophagy and capture nutrients for its growth through RAB5 and class III phosphatidylinositol 3-kinase

Lin, Mingqun; Liu, Hongyan; Xiong, Qingming; Niu, Hua; Cheng, Zhihui; Yamamoto, Akitsugu; Rikihisa, Yasuko

Ectopically expressed Etf-1 activates class III PtdIns3K, induces autophagosomes, and clears mutant HTT Ectopic expression of Etf-1 activated class III PtdIns3K in the absence of any other ehrlichial molecule, as indicated by a significantly higher amount of cellular PtdIns3P in Etf-1-transfected cells (Fig. 7A) . When GFP-ATG5 or GFP-LC3 alone was ectopically expressed, they each showed a few weak and small puncta in uninfected cells ( Fig. 4B and C) . Coexpression of Etf-1-DsRed with GFP-ATG5 or GFP-LC3 induced numerous puncta, and >80% of Etf-1 puncta colocalized with ATG5 or LC3 (Fig. S9) . BAF treatment for 16 h produced enlarged autophagosomes, in which Etf-1 and GFP-ATG5 or GFP-LC3 colocalized ( Fig. 7B and C). This indicates that Etf-1 is sufficient in inducing autophagosomes in the absence of any other ehrlichial molecules.