Calreticulin, a multi-process calcium-buffering chaperone of the endoplasmic reticulum

2009 ◽  
Vol 417 (3) ◽  
pp. 651-666 ◽  
Author(s):  
Marek Michalak ◽  
Jody Groenendyk ◽  
Eva Szabo ◽  
Leslie I. Gold ◽  
Michal Opas
Keyword(s):  
Quality Control ◽  
Endoplasmic Reticulum ◽  
Embryonic Development ◽  
Protein Disulfide Isomerase ◽  
Biological Systems ◽  
Disulfide Isomerase ◽  
Calcium Buffering ◽  
Process Property ◽  
Protein Disulfide ◽  
Er Membrane

Calreticulin is an ER (endoplasmic reticulum) luminal Ca2+-buffering chaperone. The protein is involved in regulation of intracellular Ca2+ homoeostasis and ER Ca2+ capacity. The protein impacts on store-operated Ca2+ influx and influences Ca2+-dependent transcriptional pathways during embryonic development. Calreticulin is also involved in the folding of newly synthesized proteins and glycoproteins and, together with calnexin (an integral ER membrane chaperone similar to calreticulin) and ERp57 [ER protein of 57 kDa; a PDI (protein disulfide-isomerase)-like ER-resident protein], constitutes the ‘calreticulin/calnexin cycle’ that is responsible for folding and quality control of newly synthesized glycoproteins. In recent years, calreticulin has been implicated to play a role in many biological systems, including functions inside and outside the ER, indicating that the protein is a multi-process molecule. Regulation of Ca2+ homoeostasis and ER Ca2+ buffering by calreticulin might be the key to explain its multi-process property.

scholarly journals Export of a Cysteine-Free Misfolded Secretory Protein from the Endoplasmic Reticulum for Degradation Requires Interaction with Protein Disulfide Isomerase

1999 ◽  
Vol 147 (7) ◽  
pp. 1443-1456 ◽  
Author(s):  
Pauline Gillece ◽  
José Manuel Luz ◽  
William J. Lennarz ◽  
Francisco Javier de la Cruz ◽  
Karin Römisch
Keyword(s):  
Quality Control ◽  
Protein Disulfide Isomerase ◽  
Secretory Protein ◽  
Secretory Proteins ◽  
Disulfide Isomerase ◽  
Thiol Content ◽  
Mutant Forms ◽  
Protein Disulfide ◽  
Chemical Cross Linking ◽  
Er Membrane

Protein disulfide isomerase (PDI) interacts with secretory proteins, irrespective of their thiol content, late during translocation into the ER; thus, PDI may be part of the quality control machinery in the ER. We used yeast pdi1 mutants with deletions in the putative peptide binding region of the molecule to investigate its role in the recognition of misfolded secretory proteins in the ER and their export to the cytosol for degradation. Our pdi1 deletion mutants are deficient in the export of a misfolded cysteine-free secretory protein across the ER membrane to the cytosol for degradation, but ER-to-Golgi complex transport of properly folded secretory proteins is only marginally affected. We demonstrate by chemical cross-linking that PDI specifically interacts with the misfolded secretory protein and that mutant forms of PDI have a lower affinity for this protein. In the ER of the pdi1 mutants, a higher proportion of the misfolded secretory protein remains associated with BiP, and in export-deficient sec61 mutants, the misfolded secretory protein remain bounds to PDI. We conclude that the chaperone PDI is part of the quality control machinery in the ER that recognizes terminally misfolded secretory proteins and targets them to the export channel in the ER membrane.

scholarly journals ERdj5 Reductase Cooperates with Protein Disulfide Isomerase To Promote Simian Virus 40 Endoplasmic Reticulum Membrane Translocation

2015 ◽  
Vol 89 (17) ◽  
pp. 8897-8908 ◽  
Author(s):  
Takamasa Inoue ◽  
Annie Dosey ◽  
Jeffrey F. Herbstman ◽  
Madhu Sudhan Ravindran ◽  
Georgios Skiniotis ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Disulfide Isomerase ◽  
Simian Virus 40 ◽  
Simian Virus ◽  
Membrane Penetration ◽  
Structural Rearrangements ◽  
Membrane Translocation ◽  
Disulfide Isomerase ◽  
Protein Disulfide ◽  
Er Membrane

ABSTRACTThe nonenveloped polyomavirus (PyV) simian virus 40 (SV40) traffics from the cell surface to the endoplasmic reticulum (ER), where it penetrates the ER membrane to reach the cytosol before mobilizing into the nucleus to cause infection. Prior to ER membrane penetration, ER lumenal factors impart structural rearrangements to the virus, generating a translocation-competent virion capable of crossing the ER membrane. Here we identify ERdj5 as an ER enzyme that reduces SV40's disulfide bonds, a reaction important for its ER membrane transport and infection. ERdj5 also mediates human BK PyV infection. This enzyme cooperates with protein disulfide isomerase (PDI), a redox chaperone previously implicated in the unfolding of SV40, to fully stimulate membrane penetration. Negative-stain electron microscopy of ER-localized SV40 suggests that ERdj5 and PDI impart structural rearrangements to the virus. These conformational changes enable SV40 to engage BAP31, an ER membrane protein essential for supporting membrane penetration of the virus. Uncoupling of SV40 from BAP31 traps the virus in ER subdomains called foci, which likely serve as depots from where SV40 gains access to the cytosol. Our study thus pinpoints two ER lumenal factors that coordinately prime SV40 for ER membrane translocation and establishes a functional connection between lumenal and membrane events driving this process.IMPORTANCEPyVs are established etiologic agents of many debilitating human diseases, especially in immunocompromised individuals. To infect cells at the cellular level, this virus family must penetrate the host ER membrane to reach the cytosol, a critical entry step. In this report, we identify two ER lumenal factors that prepare the virus for ER membrane translocation and connect these lumenal events with events on the ER membrane. Pinpointing cellular components necessary for supporting PyV infection should lead to rational therapeutic strategies for preventing and treating PyV-related diseases.

scholarly journals Endoplasmic Reticulum Chaperones Are Involved in the Morphogenesis of Rotavirus Infectious Particles

2008 ◽  
Vol 82 (11) ◽  
pp. 5368-5380 ◽  
Author(s):  
Liliana Maruri-Avidal ◽  
Susana López ◽  
Carlos F. Arias
Keyword(s):  
Quality Control ◽  
Endoplasmic Reticulum ◽  
Disulfide Bonds ◽  
Protein Disulfide Isomerase ◽  
Infectious Virus ◽  
The Other ◽  
Disulfide Isomerase ◽  
Virus Particles ◽  
Final Assembly ◽  
Protein Disulfide

ABSTRACT The final assembly of rotavirus particles takes place in the endoplasmic reticulum (ER). In this work, we evaluated by RNA interference the relevance to rotavirus assembly and infectivity of grp78, protein disulfide isomerase (PDI), grp94, calnexin, calreticulin, and ERp57, members of the two ER folding systems described herein. Silencing the expression of grp94 and Erp57 had no effect on rotavirus infectivity, while knocking down the expression of any of the other four chaperons caused a reduction in the yield of infectious virus of about 50%. In grp78-silenced cells, the maturation of the oligosaccharide chains of NSP4 was retarded. In cells with reduced levels of calnexin, the oxidative folding of VP7 was impaired and the trimming of NSP4 was accelerated, and in calreticulin-silenced cells, the formation of disulfide bonds of VP7 was also accelerated. The knockdown of PDI impaired the formation and/or rearrangement of the VP7 disulfide bonds. All these conditions also affected the correct assembly of virus particles, since compared with virions from control cells, they showed an altered susceptibility to EGTA and heat treatments, a decreased specific infectivity, and a diminished reactivity to VP7 with monoclonal antibody M60, which recognizes only this protein when its disulfide bonds have been correctly formed. In the case of grp78-silenced cells, the virus produced bound less efficiently to MA104 cells than virus obtained from control cells. All these results suggest that these chaperones are involved in the quality control of rotavirus morphogenesis. The complexity of the steps of rotavirus assembly that occur in the ER provide a useful model for studying the organization and operation of the complex network of chaperones involved in maintaining the quality control of this organelle.

scholarly journals Structure-Function Analysis of the Endoplasmic Reticulum Oxidoreductase TMX3 Reveals Interdomain Stabilization of the N-terminal Redox-active Domain

2007 ◽  
Vol 282 (46) ◽  
pp. 33859-33867 ◽  
Author(s):  
Johannes Haugstetter ◽  
Michael Andreas Maurer ◽  
Thomas Blicher ◽  
Martin Pagac ◽  
Gerhard Wider ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Disulfide Isomerase ◽  
Function Analysis ◽  
Transmembrane Protein ◽  
Reduced Form ◽  
Disulfide Isomerase ◽  
Binding Domains ◽  
Redox Active ◽  
Protein Disulfide ◽  
Protein Disulfide Isomerase Family

Disulfide bond formation in the endoplasmic reticulum is catalyzed by enzymes of the protein disulfide-isomerase family that harbor one or more thioredoxin-like domains. We recently discovered the transmembrane protein TMX3, a thiol-disulfide oxidoreductase of the protein disulfide-isomerase family. Here, we show that the endoplasmic reticulum-luminal region of TMX3 contains three thioredoxin-like domains, an N-terminal redox-active domain (named a) followed by two enzymatically inactive domains (b and b′). Using the recombinantly expressed TMX3 domain constructs a, ab, and abb′, we compared structural stability and enzymatic properties. By structural and biophysical methods, we demonstrate that the reduced a domain has features typical of a globular folded domain that is, however, greatly destabilized upon oxidization. Importantly, interdomain stabilization by the b domain renders the a domain more resistant toward chemical denaturation and proteolysis in both the oxidized and reduced form. In combination with molecular modeling studies of TMX3 abb′, the experimental results provide a new understanding of the relationship between the multidomain structure of TMX3 and its function as a redox enzyme. Overall, the data indicate that in addition to their role as substrate and co-factor binding domains, redox-inactive thioredoxin-like domains also function in stabilizing neighboring redox-active domains.

scholarly journals Identification of a Novel Saturable Endoplasmic Reticulum Localization Mechanism Mediated by the C-Terminus of aDictyostelium Protein Disulfide Isomerase

2000 ◽  
Vol 11 (10) ◽  
pp. 3469-3484 ◽  
Author(s):  
Jean Monnat ◽  
Eva M. Neuhaus ◽  
Marius S. Pop ◽  
David M. Ferrari ◽  
Barbara Kramer ◽  
...  
Keyword(s):  
Endoplasmic Reticulum ◽  
Protein Disulfide Isomerase ◽  
Fluorescent Protein ◽  
Null Mutation ◽  
Disulfide Isomerase ◽  
Isomerase Activity ◽  
C Terminus ◽  
Complementary Action ◽  
Green Fluorescent ◽  
Protein Disulfide

Localization of soluble endoplasmic reticulum (ER) resident proteins is likely achieved by the complementary action of retrieval and retention mechanisms. Whereas the machinery involving the H/KDEL and related retrieval signals in targeting escapees back to the ER is well characterized, other mechanisms including retention are still poorly understood. We have identified a protein disulfide isomerase (Dd-PDI) lacking the HDEL retrieval signal normally found at the C terminus of ER residents in Dictyostelium discoideum. Here we demonstrate that its 57 residue C-terminal domain is necessary for intracellular retention of Dd-PDI and sufficient to localize a green fluorescent protein (GFP) chimera to the ER, especially to the nuclear envelope. Dd-PDI and GFP-PDI57 are recovered in similar cation-dependent complexes. The overexpression of GFP-PDI57 leads to disruption of endogenous PDI complexes and induces the secretion of PDI, whereas overexpression of a GFP-HDEL chimera induces the secretion of endogenous calreticulin, revealing the presence of two independent and saturable mechanisms. Finally, low-level expression of Dd-PDI but not of PDI truncated of its 57 C-terminal residues complements the otherwise lethal yeast TRG1/PDI1 null mutation, demonstrating functional disulfide isomerase activity and ER localization. Altogether, these results indicate that the PDI57 peptide contains ER localization determinants recognized by a conserved machinery present in D. discoideum and Saccharomyces cerevisiae.

The yeast EUG1 gene encodes an endoplasmic reticulum protein that is functionally related to protein disulfide isomerase

1992 ◽  
Vol 12 (10) ◽  
pp. 4601-4611
Author(s):  
C Tachibana ◽  
T H Stevens
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Endoplasmic Reticulum ◽  
Protein Disulfide Isomerase ◽  
Yeast Cells ◽  
Disulfide Isomerase ◽  
Protein Levels ◽  
Growth Defects ◽  
Endoplasmic Reticulum Protein ◽  
Related Proteins ◽  
Protein Disulfide

The product of the EUG1 gene of Saccharomyces cerevisiae is a soluble endoplasmic reticulum protein with homology to both the mammalian protein disulfide isomerase (PDI) and the yeast PDI homolog encoded by the essential PDI1 gene. Deletion or overexpression of EUG1 causes no growth defects under a variety of conditions. EUG1 mRNA and protein levels are dramatically increased in response to the accumulation of native or unglycosylated proteins in the endoplasmic reticulum. Overexpression of the EUG1 gene allows yeast cells to grow in the absence of the PDI1 gene product. Depletion of the PDI1 protein in Saccharomyces cerevisiae causes a soluble vacuolar glycoprotein to accumulate in its endoplasmic reticulum form, and this phenotype is only partially relieved by the overexpression of EUG1. Taken together, our results indicate that PDI1 and EUG1 encode functionally related proteins that are likely to be involved in interacting with nascent polypeptides in the yeast endoplasmic reticulum.

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