AMPylation matches BiP activity to client protein load in the endoplasmic reticulum

  1. Steffen Preissler
  2. Cláudia Rato
  3. Ruming Chen
  4. Robin Antrobus
  5. Shujing Ding
  6. Ian M Fearnley
  7. David Ron  Is a corresponding author
  1. University of Cambridge, United Kingdom
  2. MRC Mitochondrial Biology Unit, United Kingdom

Abstract

The endoplasmic reticulum (ER) localized Hsp70 chaperone BiP affects protein folding homeostasis and the response to ER stress. Reversible inactivating covalent modification of BiP is believed to contribute to the balance between chaperones and unfolded ER proteins, but the nature of this modification has so far been hinted at indirectly. We report that deletion of FICD, a gene encoding an ER-localized AMPylating enzyme, abolished detectable modification of endogenous BiP enhancing ER buffering of unfolded protein stress in mammalian cells, whilst deregulated FICD activity had the opposite effect. In vitro, FICD AMPylated BiP to completion on a single residue, Thr518. AMPylation increased, in a strictly FICD-dependent manner, as the flux of proteins entering the ER was attenuated in vivo. In vitro, Thr518 AMPylation enhanced peptide dissociation from BiP 6-fold and abolished stimulation of ATP hydrolysis by J-domain cofactor. These findings expose the molecular basis for covalent inactivation of BiP.

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Author details

  1. Steffen Preissler

    Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.
  2. Cláudia Rato

    Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.
  3. Ruming Chen

    Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.
  4. Robin Antrobus

    Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.
  5. Shujing Ding

    MRC Mitochondrial Biology Unit, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.
  6. Ian M Fearnley

    MRC Mitochondrial Biology Unit, Cambridge, United Kingdom
    Competing interests
    No competing interests declared.
  7. David Ron

    Cambridge Institute for Medical Research, University of Cambridge, Cambridge, United Kingdom
    For correspondence
    dr360@medschl.cam.ac.uk
    Competing interests
    David Ron, Reviewing editor, eLife.

Copyright

© 2015, Preissler et al.

This article is distributed under the terms of the Creative Commons Attribution License permitting unrestricted use and redistribution provided that the original author and source are credited.

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https://doi.org/10.7554/eLife.12621

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