Endoplasmic reticulum-resident protein 57 (ERp57) oxidatively inactivates human transglutaminase 2

J Biol Chem. 2018 Feb 23;293(8):2640-2649. doi: 10.1074/jbc.RA117.001382. Epub 2018 Jan 5.

Abstract

Transglutaminase 2 (TG2) is a ubiquitously expressed, intracellular as well as extracellular protein with multiple modes of post-translational regulation, including an allosteric disulfide bond between Cys-370-Cys-371 that renders the enzyme inactive in the extracellular matrix. Although recent studies have established that extracellular TG2 is switched "on" by the redox cofactor protein thioredoxin-1 (TRX), it is unclear how TG2 is switched "off." Here, we demonstrate that TG2 oxidation by small-molecule biological oxidants, including glutathione, cystine, and hydrogen peroxide, is unlikely to be the inactivation mechanism. Instead, endoplasmic reticulum (ER)-resident protein 57 (ERp57), a protein in the ER that promotes folding of nascent proteins and is also present in the extracellular environment, has the cellular and biochemical characteristics for inactivating TG2. We found that ERp57 colocalizes with extracellular TG2 in cultured human umbilical vein endothelial cells (HUVECs). ERp57 oxidized TG2 with a rate constant that was 400-2000-fold higher than those of the aforementioned small molecule oxidants. Moreover, its specificity for TG2 was also markedly higher than those of other secreted redox proteins, including protein disulfide isomerase (PDI), ERp72, TRX, and quiescin sulfhydryl oxidase 1 (QSOX1). Lastly, siRNA-mediated ERp57 knockdown in HUVECs increased TG2-catalyzed transamidation in the extracellular environment. We conclude that, to the best of our knowledge, the disulfide bond switch in human TG2 represents the first example of a post-translational redox regulatory mechanism that is reversibly and allosterically modulated by two distinct proteins (ERp57 and TRX).

Keywords: ERp57; PDIA3; celiac disease; disulfide; oxidation-reduction (redox); post-translational modification (PTM); protein disulfide isomerase family A member 3; redox switch; thioredoxin; transglutaminase; transglutaminase 2.

Publication types

  • Research Support, N.I.H., Extramural

MeSH terms

  • Allosteric Regulation / drug effects
  • Biocatalysis / drug effects
  • Cells, Cultured
  • Cystine / metabolism
  • Enzymes, Immobilized / antagonists & inhibitors
  • Enzymes, Immobilized / metabolism
  • Extracellular Matrix / drug effects
  • Extracellular Matrix / enzymology*
  • Extracellular Matrix / metabolism
  • GTP-Binding Proteins / antagonists & inhibitors*
  • GTP-Binding Proteins / chemistry
  • GTP-Binding Proteins / genetics
  • GTP-Binding Proteins / metabolism
  • Glutathione / metabolism
  • Human Umbilical Vein Endothelial Cells / cytology
  • Human Umbilical Vein Endothelial Cells / enzymology
  • Human Umbilical Vein Endothelial Cells / metabolism
  • Humans
  • Hydrogen Peroxide / pharmacology
  • Membrane Glycoproteins / chemistry
  • Membrane Glycoproteins / genetics
  • Membrane Glycoproteins / metabolism
  • Oxidants / metabolism
  • Oxidants / pharmacology
  • Oxidation-Reduction
  • Oxidoreductases Acting on Sulfur Group Donors / chemistry
  • Oxidoreductases Acting on Sulfur Group Donors / genetics
  • Oxidoreductases Acting on Sulfur Group Donors / metabolism
  • Peptide Fragments / chemistry
  • Peptide Fragments / genetics
  • Peptide Fragments / metabolism
  • Protein Disulfide-Isomerases / antagonists & inhibitors
  • Protein Disulfide-Isomerases / genetics
  • Protein Disulfide-Isomerases / metabolism*
  • Protein Glutamine gamma Glutamyltransferase 2
  • Protein Processing, Post-Translational* / drug effects
  • Protein Transport / drug effects
  • RNA Interference
  • Recombinant Proteins / chemistry
  • Recombinant Proteins / metabolism
  • Thioredoxins / genetics
  • Thioredoxins / metabolism
  • Transglutaminases / antagonists & inhibitors*
  • Transglutaminases / chemistry
  • Transglutaminases / genetics
  • Transglutaminases / metabolism

Substances

  • Enzymes, Immobilized
  • Membrane Glycoproteins
  • Oxidants
  • Peptide Fragments
  • Recombinant Proteins
  • endoplasmic reticulum glycoprotein p72
  • Cystine
  • Thioredoxins
  • Hydrogen Peroxide
  • Oxidoreductases Acting on Sulfur Group Donors
  • QSOX1 protein, human
  • Protein Glutamine gamma Glutamyltransferase 2
  • Transglutaminases
  • GTP-Binding Proteins
  • Protein Disulfide-Isomerases
  • PDIA3 protein, human
  • Glutathione