Top

Research Article

Split Viewer

Mol. Cells 2011; 32(5): 459-475

Published online November 30, 2011

https://doi.org/10.1007/s10059-011-0150-3

© The Korean Society for Molecular and Cellular Biology

Protein Disulfide Isomerase-2 of Arabidopsis Mediates Protein Folding and Localizes to Both the Secretory Pathway and Nucleus, Where It Interacts with Maternal Effect Embryo Arrest Factor

Eun Ju Cho, Christen Y.L. Yuen, Byung-Ho Kang1, Christine A. Ondzighi2, L. Andrew Staehelin2, and David A. Christopher*

Department of Molecular Biosciences and Bioengineering, University of Hawaii, USA, 1Department of Microbiology and Cell Science, University of Florida, USA, 2Department of Molecular, Cellular and Developmental Biology, University of Colorado, USA

Correspondence to : *Correspondence: dchr@Hawaii.edu

Received: July 19, 2011; Revised: August 13, 2011; Accepted: August 16, 2011

Abstract

Protein disulfide isomerase (PDI) is a thiodisulfide oxidoreductase that catalyzes the formation, reduction and rearrangement of disulfide bonds in proteins of eukaryotes. The classical PDI has a signal peptide, two CXXC-containing thioredoxin catalytic sites (a,a?), two noncatalytic thioredoxin fold domains (b,b?), an acidic domain (c) and a C-terminal endoplasmic reticulum (ER) retention signal. Although PDI resides in the ER where it mediates the folding of nascent polypeptides of the secretory pathway, we recently showed that PDI5 of Arabidopsis thaliana chaperones and inhibits cysteine proteases during traf-ficking to vacuoles prior to programmed cell death of the endothelium in developing seeds. Here we describe Arabidopsis PDI2, which shares a primary structure similar to that of classical PDI. Recombinant PDI2 is imported into ER-derived microsomes and complements the E. coli protein-folding mutant, dsbA. PDI2 interacted with proteins in both the ER and nucleus, including ER-resident protein folding chaperone, BiP1, and nuclear embryo transcription factor, MEE8. The PDI2-MEE8 interaction was confirmed to occur in vitro and in vivo. Transient expression of PDI2-GFP fusions in mesophyll protoplasts resulted in labeling of the ER, nucleus and vacuole. PDI2 is expressed in multiple tissues, with relatively high expression in seeds and root tips. Immunoelectron microscopy with GFP- and PDI2-specific antisera on transgenic seeds (PDI2-GFP) and wild type roots demonstrated that PDI2 was found in the secretory pathway (ER, Golgi, vacuole, cell wall) and the nuclei. Our results indicate that PDI2 mediates protein folding in the ER and has new functional roles in the nucleus.

Keywords chaperone, endoplasmic reticulum, nuclear factor, plant disulfide isomerase, protein folding

Article

Research Article

Mol. Cells 2011; 32(5): 459-475

Published online November 30, 2011 https://doi.org/10.1007/s10059-011-0150-3

Copyright © The Korean Society for Molecular and Cellular Biology.

Protein Disulfide Isomerase-2 of Arabidopsis Mediates Protein Folding and Localizes to Both the Secretory Pathway and Nucleus, Where It Interacts with Maternal Effect Embryo Arrest Factor

Eun Ju Cho, Christen Y.L. Yuen, Byung-Ho Kang1, Christine A. Ondzighi2, L. Andrew Staehelin2, and David A. Christopher*

Department of Molecular Biosciences and Bioengineering, University of Hawaii, USA, 1Department of Microbiology and Cell Science, University of Florida, USA, 2Department of Molecular, Cellular and Developmental Biology, University of Colorado, USA

Correspondence to:*Correspondence: dchr@Hawaii.edu

Received: July 19, 2011; Revised: August 13, 2011; Accepted: August 16, 2011

Abstract

Protein disulfide isomerase (PDI) is a thiodisulfide oxidoreductase that catalyzes the formation, reduction and rearrangement of disulfide bonds in proteins of eukaryotes. The classical PDI has a signal peptide, two CXXC-containing thioredoxin catalytic sites (a,a?), two noncatalytic thioredoxin fold domains (b,b?), an acidic domain (c) and a C-terminal endoplasmic reticulum (ER) retention signal. Although PDI resides in the ER where it mediates the folding of nascent polypeptides of the secretory pathway, we recently showed that PDI5 of Arabidopsis thaliana chaperones and inhibits cysteine proteases during traf-ficking to vacuoles prior to programmed cell death of the endothelium in developing seeds. Here we describe Arabidopsis PDI2, which shares a primary structure similar to that of classical PDI. Recombinant PDI2 is imported into ER-derived microsomes and complements the E. coli protein-folding mutant, dsbA. PDI2 interacted with proteins in both the ER and nucleus, including ER-resident protein folding chaperone, BiP1, and nuclear embryo transcription factor, MEE8. The PDI2-MEE8 interaction was confirmed to occur in vitro and in vivo. Transient expression of PDI2-GFP fusions in mesophyll protoplasts resulted in labeling of the ER, nucleus and vacuole. PDI2 is expressed in multiple tissues, with relatively high expression in seeds and root tips. Immunoelectron microscopy with GFP- and PDI2-specific antisera on transgenic seeds (PDI2-GFP) and wild type roots demonstrated that PDI2 was found in the secretory pathway (ER, Golgi, vacuole, cell wall) and the nuclei. Our results indicate that PDI2 mediates protein folding in the ER and has new functional roles in the nucleus.

Keywords: chaperone, endoplasmic reticulum, nuclear factor, plant disulfide isomerase, protein folding

Mol. Cells
Nov 30, 2022 Vol.45 No.11, pp. 763~867
COVER PICTURE
Naive (cyan) and axotomized (magenta) retinal ganglion cell axons in Xenopus tropicalis (Choi et al., pp. 846-854).

Supplementary File

Share this article on

  • line
  • mail

Related articles in Mol. Cells

Molecules and Cells

eISSN 0219-1032
qr-code Download