scholarly journals Effects of Inactivation and Constitutive Expression of the Unfolded- Protein Response Pathway on Protein Production in the Yeast Saccharomyces cerevisiae

2003 ◽  
Vol 69 (4) ◽  
pp. 2065-2072 ◽  
Author(s):  
Mari Valkonen ◽  
Merja Penttilä ◽  
Markku Saloheimo
Keyword(s):  
Saccharomyces Cerevisiae ◽  
Unfolded Protein Response ◽  
Protein Production ◽  
Active Form ◽  
Constitutive Expression ◽  
Amylase Secretion ◽  
Unfolded Protein ◽  
Foreign Proteins ◽  
The Unfolded Protein Response ◽  
Protein Response

ABSTRACT One strategy to obtain better yields of secreted proteins has been overexpression of single endoplasmic reticulum-resident foldases or chaperones. We report here that manipulation of the unfolded-protein response (UPR) pathway regulator, HAC1, affects production of both native and foreign proteins in the yeast Saccharomyces cerevisiae. The effects of HAC1 deletion and overexpression on the production of a native protein, invertase, and two foreign proteins, Bacillus amyloliquefaciens α-amylase and Trichoderma reesei endoglucanase EGI, were studied. Disruption of HAC1 caused decreases in the secretion of both α-amylase (70 to 75% reduction) and EGI (40 to 50% reduction) compared to the secretion by the parental strain. Constitutive overexpression of HAC1 caused a 70% increase in α-amylase secretion but had no effect on EGI secretion. The invertase levels were twofold higher in the strain overexpressing HAC1. Also, the effect of the active form of T. reesei hac1 was tested in S. cerevisiae. hac1 expression caused a 2.4-fold increase in the secretion of α-amylase in S. cerevisiae and also slight increases in invertase and total protein production. Overexpression of both S. cerevisiae HAC1 and T. reesei hac1 caused an increase in the expression of the known UPR target gene KAR2 at early time points during cultivation.

scholarly journals Improvement of Foreign-Protein Production in Aspergillus niger var. awamori by Constitutive Induction of the Unfolded-Protein Response

2003 ◽  
Vol 69 (12) ◽  
pp. 6979-6986 ◽  
Author(s):  
Mari Valkonen ◽  
Michael Ward ◽  
Huaming Wang ◽  
Merja Penttilä ◽  
Markku Saloheimo
Keyword(s):  
Aspergillus Niger ◽  
Unfolded Protein Response ◽  
Protein Production ◽  
Production Systems ◽  
Foreign Protein ◽  
Mrna Levels ◽  
Unfolded Protein ◽  
Novel Strategy ◽  
The Unfolded Protein Response ◽  
Protein Response

ABSTRACT Unfolded-protein response (UPR) denotes the upregulation of endoplasmic reticulum (ER)-resident chaperone and foldase genes and numerous other genes involved in secretory functions during the accumulation of unfolded proteins into the ER. Overexpression of individual foldases and chaperones has been used in attempts to improve protein production in different production systems. We describe here a novel strategy to improve foreign-protein production. We show that the constitutive induction of the UPR pathway in Aspergillus niger var. awamori can be achieved by expressing the activated form of the transcription factor hacA. This induction enhances the production of Trametes versicolor laccase by up to sevenfold and of bovine preprochymosin by up to 2.8-fold in this biotechnically important fungus. The regulatory range of UPR was studied by analyzing the mRNA levels of novel A. niger var. awamori genes involved in different secretory functions. This revealed both similarities and differences to corresponding studies in Saccharomyces cerevisiae.

scholarly journals The Unfolded Protein Response: An Overview

Biology ◽  
2021 ◽  
Vol 10 (5) ◽  
pp. 384
Author(s):  
Adam Read ◽  
Martin Schröder
Keyword(s):  
Gene Expression ◽  
Saccharomyces Cerevisiae ◽  
Unfolded Protein Response ◽  
Protein Homeostasis ◽  
Unfolded Proteins ◽  
Unfolded Protein ◽  
Altered Glycosylation ◽  
Stressed Cells ◽  
The Unfolded Protein Response ◽  
Protein Response

The unfolded protein response is the mechanism by which cells control endoplasmic reticulum (ER) protein homeostasis. Under normal conditions, the UPR is not activated; however, under certain stresses, such as hypoxia or altered glycosylation, the UPR can be activated due to an accumulation of unfolded proteins. The activation of the UPR involves three signaling pathways, IRE1, PERK and ATF6, which all play vital roles in returning protein homeostasis to levels seen in non-stressed cells. IRE1 is the best studied of the three pathways, as it is the only pathway present in Saccharomyces cerevisiae. This pathway involves spliceosome independent splicing of HAC1 or XBP1 in yeast and mammalians cells, respectively. PERK limits protein synthesis, therefore reducing the number of new proteins requiring folding. ATF6 is translocated and proteolytically cleaved, releasing a NH2 domain fragment which is transported to the nucleus and which affects gene expression. If the UPR is unsuccessful at reducing the load of unfolded proteins in the ER and the UPR signals remain activated, this can lead to programmed cell death.

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