AMPylation matches BiP activity to client protein load in the endoplasmic reticulum
- University of Cambridge, United Kingdom
- 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.
Article and author information
Author details
Reviewing Editor
- Reid Gilmore, University of Massachusetts Medical School, United States
Version history
- Received: October 27, 2015
- Accepted: December 14, 2015
- Accepted Manuscript published: December 17, 2015 (version 1)
- Version of Record published: January 22, 2016 (version 2)
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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AMPylation matches BiP activity to client protein load in the endoplasmic reticulum
eLife 4:e12621.
https://doi.org/10.7554/eLife.12621
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