Unrestrained AMPylation targets cytosolic chaperones and activates the heat shock response

Proc Natl Acad Sci U S A. 2017 Jan 10;114(2):E152-E160. doi: 10.1073/pnas.1619234114. Epub 2016 Dec 28.

Abstract

Protein AMPylation is a conserved posttranslational modification with emerging roles in endoplasmic reticulum homeostasis. However, the range of substrates and cell biological consequences of AMPylation remain poorly defined. We expressed human and Caenorhabditis elegans AMPylation enzymes-huntingtin yeast-interacting protein E (HYPE) and filamentation-induced by cyclic AMP (FIC)-1, respectively-in Saccharomyces cerevisiae, a eukaryote that lacks endogenous protein AMPylation. Expression of HYPE and FIC-1 in yeast induced a strong cytoplasmic Hsf1-mediated heat shock response, accompanied by attenuation of protein translation, massive protein aggregation, growth arrest, and lethality. Overexpression of Ssa2, a cytosolic heat shock protein (Hsp)70, was sufficient to partially rescue growth. In human cell lines, overexpression of active HYPE similarly induced protein aggregation and the HSF1-dependent heat shock response. Excessive AMPylation also abolished HSP70-dependent influenza virus replication. Our findings suggest a mode of Hsp70 inactivation by AMPylation and point toward a role for protein AMPylation in the regulation of cellular protein homeostasis beyond the endoplasmic reticulum.

Keywords: AMPylation; FIC protein; HSP70; chaperones; proteostasis.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Caenorhabditis elegans
  • Caenorhabditis elegans Proteins / genetics
  • Caenorhabditis elegans Proteins / metabolism*
  • Carrier Proteins / genetics
  • Carrier Proteins / metabolism*
  • Cell Line
  • Cyclic AMP / metabolism*
  • Cytosol / metabolism
  • HSP70 Heat-Shock Proteins / metabolism*
  • Heat-Shock Response / physiology*
  • Humans
  • Influenza A virus / physiology
  • Influenza, Human
  • Membrane Proteins / genetics
  • Membrane Proteins / metabolism*
  • Nucleotidyltransferases / genetics
  • Nucleotidyltransferases / metabolism*
  • Protein Processing, Post-Translational
  • Saccharomyces cerevisiae / genetics
  • Virus Replication

Substances

  • Caenorhabditis elegans Proteins
  • Carrier Proteins
  • HSP70 Heat-Shock Proteins
  • Membrane Proteins
  • Cyclic AMP
  • FIC-1 protein, C elegans
  • HypE protein, human
  • Nucleotidyltransferases