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Updated: Oct 10, 2026

Study of Protein-protein Interactions in Autophagy Research
Published on: September 9, 2017
TBK1-mediated phosphorylation of WIPI2 links bacteria recognition to autophagosome formation in xenophagy
Chuying Qian1, Hongtao Zhang1, Jin Li1
1Department of Respiratory and Critical Care Medicine, Center for Metabolism Research, the Fourth Affiliated Hospital of Zhejiang University School of Medicine, International School of Medicine, International Institutes of Medicine, Zhejiang University, Yiwu, Zhejiang, China.
Abstract:
Xenophagy, a selective autophagy pathway, is a critical innate immune defense mechanism that targets pathogens for lysosomal degradation. However, the molecular mechanisms enabling autophagosomes to specifically recognize and engulf bacteria remain incompletely understood. Here, we identify WIPI2, a core component that drives autophagosome biogenesis, as a novel phosphorylation substrate of TBK1 during Salmonella Typhimurium infection. We demonstrate that TBK1 phosphorylates WIPI2 at Ser96, which enhances its interaction with ATG16L1 and its binding to PtdIns3P. Crucially, the recruitment of WIPI2 to intracellular bacteria is dependent on its interaction with ATG16L1, which is localized to the Salmonella-containing vacuole. Furthermore, TBK1-mediated phosphorylation of WIPI2 is required for efficient bacterial clearance. Collectively, our findings reveal a molecular mechanism whereby TBK1-mediated phosphorylation of WIPI2 directs localized phagophore expansion around invading bacteria, thereby bridging bacterial recognition with autophagosome assembly.Abbreviations: ATG: autophagy related; ATG5: autophagy related 5; ATG16L1: autophagy related 16 like 1; CALCOCO2/NDP52: calcium binding and coiled-coil domain 2; CFU: colony-forming units; GFP: green fluorescent protein; GST: glutathione S-transferase; IL6: interleukin 6; KO: knockout; LPS: lipopolysaccharides; MAP1LC3/LC3: microtubule associated protein 1 light chain 3; OPTN: optineurin; PtdIns: phosphatidylinositol; PtdIns3P: phosphatidylinositol-3-phosphate; RB1CC1/FIP200: RB1 inducible coiled-coil 1; RFP: red fluorescent protein;S. Typhimurium:SalmonellaTyphimurium; SCV:SalmonellaTyphimurium-containing vacuole; SQSTM1/p62: sequestosome 1; TBK1/NAK: TANK binding kinase 1; ULK1: unc-51 like autophagy activating kinase 1; V-ATPase: vacuolar-type H+-translocating ATPase; WIPI1: WD repeat domain, phosphoinositide interacting 1; WIPI2: WD repeat domain, phosphoinositide interacting 2; WT: wild-type.
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