Repository logo
 

FICD acts bifunctionally to AMPylate and de-AMPylate the endoplasmic reticulum chaperone BiP

Accepted version
Peer-reviewed

Type

Article

Change log

Authors

Rato, C 
Perera, LA 
Saudek, V 

Abstract

Protein folding homeostasis in the endoplasmic reticulum (ER) is defended by an unfolded protein response that matches ER chaperone capacity to the burden of unfolded proteins. As levels of unfolded proteins decline, a metazoan-specific FIC-domain-containing ER-localized enzyme (FICD) rapidly inactivates the major ER chaperone BiP by AMPylating T518. Here we show that the single catalytic domain of FICD can also release the attached AMP, restoring functionality to BiP. Consistent with a role for endogenous FICD in de-AMPylating BiP, FICD/ hamster cells are hypersensitive to introduction of a constitutively AMPylating, de-AMPylation-defective mutant FICD. These opposing activities hinge on a regulatory residue, E234, whose default state renders FICD a constitutive de-AMPylase in vitro. The location of E234 on a conserved regulatory helix and the mutually antagonistic activities of FICD in vivo, suggest a mechanism whereby fluctuating unfolded protein load actively switches FICD from a de-AMPylase to an AMPylase.

Description

Keywords

Adenosine Monophosphate, Animals, Biocatalysis, CHO Cells, Carrier Proteins, Catalytic Domain, Cricetinae, Cricetulus, Endoplasmic Reticulum Chaperone BiP, HEK293 Cells, Heat-Shock Proteins, Humans, Kinetics, Membrane Proteins, Nucleotidyltransferases, Protein Binding, Protein Processing, Post-Translational

Journal Title

Nature Structural and Molecular Biology

Conference Name

Journal ISSN

1545-9993
1545-9985

Volume Title

24

Publisher

Nature Publishing Group
Sponsorship
Wellcome Trust (084812/Z/08/Z)
Wellcome Trust (200848/Z/16/Z)
Wellcome Trust (100140/Z/12/Z)
Supported by Wellcome Trust Principal Research Fellowship to D.R. (Wellcome 200848/Z/16/Z), a UK Medical Research Council PhD studentship to L.A.P. and a Wellcome Trust Strategic Award to the Cambridge Institute for Medical Research (Wellcome 100140).