title: The Autophagy Receptor TAX1BP1 and the Molecular Motor Myosin VI Are Required for Clearance of Salmonella Typhimurium by Autophagy.
abstract: Autophagy plays a key role during Salmonella infection, by eliminating these pathogens following escape into the cytosol. In this process, selective autophagy receptors, including the myosin VI adaptor proteins optineurin and NDP52, have been shown to recognize cytosolic pathogens. Here, we demonstrate that myosin VI and TAX1BP1 are recruited to ubiquitylated Salmonella and play a key role in xenophagy. The absence of TAX1BP1 causes an accumulation of ubiquitin-positive Salmonella, whereas loss of myosin VI leads to an increase in ubiquitylated and LC3-positive bacteria. Our structural studies demonstrate that the ubiquitin-binding site of TAX1BP1 overlaps with the myosin VI binding site and point mutations in the TAX1BP1 zinc finger domains that affect ubiquitin binding also ablate binding to myosin VI. This mutually exclusive binding and the association of TAX1BP1 with LC3 on the outer limiting membrane of autophagosomes may suggest a molecular mechanism for recruitment of this motor to autophagosomes. The predominant role of TAX1BP1, a paralogue of NDP52, in xenophagy is supported by our evolutionary analysis, which demonstrates that functionally intact NDP52 is missing in Xenopus and mice, whereas TAX1BP1 is expressed in all vertebrates analysed. In summary, this work highlights the importance of TAX1BP1 as a novel autophagy receptor in myosin VI-mediated xenophagy. Our study identifies essential new machinery for the autophagy-dependent clearance of Salmonella typhimurium and suggests modulation of myosin VI motor activity as a potential therapeutic target in cellular immunity.
authors.affiliation: Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom.
authors.forename: David A
authors.initials: DA
authors.lastname: Tumbarello
authors.affiliation: Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Paul T
authors.initials: PT
authors.lastname: Manna
authors.affiliation: MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Allen
authors.affiliation: MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.
authors.forename: Mark
authors.initials: M
authors.lastname: Bycroft
authors.affiliation: Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Susan D
authors.initials: SD
authors.lastname: Arden
authors.affiliation: MRC Laboratory of Molecular Biology, Cambridge, United Kingdom.
authors.forename: John
authors.initials: J
authors.lastname: Kendrick-Jones
authors.affiliation: Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom.
authors.forename: Folma
authors.initials: F
authors.lastname: Buss
mesh_terms: D000818:Animals; D001343:Autophagy / Q000276:immunology*; D015153:Blotting, Western; D002478:Cells, Cultured; D055785:Gene Knockdown Techniques; D006367:HeLa Cells; D006801:Humans; D047468:Immunoprecipitation; D047908:Intracellular Signaling Peptides and Proteins / Q000276:immunology* / Q000378:metabolism; D009682:Magnetic Resonance Spectroscopy; D051379:Mice; D008856:Microscopy, Fluorescence; D008969:Molecular Sequence Data; D018995:Myosin Heavy Chains / Q000276:immunology* / Q000378:metabolism; D009363:Neoplasm Proteins / Q000276:immunology* / Q000378:metabolism; D010802:Phylogeny; D011487:Protein Conformation; D012480:Salmonella Infections / Q000276:immunology* / Q000378:metabolism; D012486:Salmonella typhimurium / Q000276:immunology / Q000378:metabolism; D054875:Ubiquitination
chemical_list: D047908:Intracellular Signaling Peptides and Proteins; D009363:Neoplasm Proteins; C120635:TAX1BP1 protein, human; C089785:myosin VI; D018995:Myosin Heavy Chains