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The Autophagy Receptor TAX1BP1 and the Molecular Motor Myosin VI Are Required for Clearance of Salmonella Typhimurium by Autophagy.


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Authors

Tumbarello, David A 
Manna, Paul T 
Allen, Mark 
Bycroft, Mark 
Arden, Susan D 

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.

Description

Keywords

Animals, Autophagy, Blotting, Western, Cells, Cultured, Gene Knockdown Techniques, HeLa Cells, Humans, Immunoprecipitation, Intracellular Signaling Peptides and Proteins, Magnetic Resonance Spectroscopy, Mice, Microscopy, Fluorescence, Molecular Sequence Data, Myosin Heavy Chains, Neoplasm Proteins, Phylogeny, Protein Conformation, Salmonella Infections, Salmonella typhimurium, Ubiquitination

Journal Title

PLoS Pathog

Conference Name

Journal ISSN

1553-7366
1553-7374

Volume Title

11

Publisher

Public Library of Science (PLoS)
Sponsorship
Medical Research Council (MR/K000888/1)
Wellcome Trust (100140/Z/12/Z)
Wellcome Trust (086743/Z/08/Z)
Wellcome Trust (093026/Z/10/Z)
Biotechnology and Biological Sciences Research Council (BB/K001981/1)
FB and DAT thank the Wellcome Trust (www.wellcome.ac.uk) for funding of a University Award to FB (086743), the CIMR Strategic Award (100140) and an equipment grant [093026]. FB also thanks the Medical Research Council UK (www.mrc.ac.uk) for funding of a project grant (MR/K000888/1). JKJ, MA and MB were supported by the Medical Research Council UK (www.mrc.ac.uk) (U105184325).