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Analysis of the role of the gene bipA, encoding the major endoplasmic reticulum chaperone protein in the secretion of homologous and heterologous proteins in black Aspergilli

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Author: Punt, P.J. · Gemeren, I.A. van · Drint-Kuijvenhoven, J. · Hessing, J.G.M. · Muijlwijk van - Harteveld, G.M. · Beijersbergen, A. · Verrips, C.T. · Hondel, C.A.M.J.J. van den
Type:article
Date:1998
Institution: Centraal Instituut voor Voedingsonderzoek TNO
Source:Applied Microbiology and Biotechnology, 4, 50, 447-454
Identifier: 234678
doi: DOI:10.1007/s002530051319
Keywords: Nutrition · Binding protein · Chaperone · Glucan 1,4 alpha glucosidase · Recombinant protein · Aspergillus awamori · Aspergillus niger · Endoplasmic reticulum · Fungal genetics · Gene fusion · Gene overexpression · Nonhuman · Promoter region · Protein secretion · Animals · Antibody Specificity · Artificial Gene Fusion · Aspergillus · Aspergillus niger · Blotting, Northern · Blotting, Western · Cloning, Molecular · Fungal Proteins · Gene Expression Regulation, Fungal · Genes, Fungal · Glucan 1,4-alpha-Glucosidase · HSP70 Heat-Shock Proteins · Rabbits · Recombinant Fusion Proteins · Aspergillus · Aspergillus awamori · Aspergillus niger · Fungi

Abstract

The function of the endoplasmic-reticulum-localized chaperone binding protein (BiP) in relation to protein secretion in filamentous fungi was studied. It was shown that the overproduction of several homologous and heterologous recombinant proteins by Aspergillus strains induces the expression of bipA, the BiP-encoding gene from Aspergillus niger and Aspergillus awamori. As this result could imply that BiP plays a role in protein overproduction, the effect of modulation of bipA gene expression on protein secretion was studied in several recombinant strains expressing glucoamylase (glaA) fusion genes. For overproduction of BiPA in these strains, extra copies of the bipA gene under the control of an inducible promoter were introduced. To allow analysis of the effect of a decreased bipA expression level on protein secretion, replacement of the wild-type gene for a bipA gene driven by the glaA promoter was attempted. However, this endeavour failed because of the lethality of this replacement. Although the final amount of secreted recombinant protein did not change significantly in strains with increased BiPA levels, increased levels of unprocessed fusion protein were detected in the total protein extracts of these strains.