Calnexin Overexpression Increases Manganese Peroxidase Production in
            <i>Aspergillus niger</i>

Conesa, Ana; Jeenes, David J.; Archer, David B.; Hondel, Cees A. M. J. J. van den; Punt, Peter J.

doi:10.1128/aem.68.2.846-851.2002

Cited by 76 publications

(42 citation statements)

References 47 publications

(51 reference statements)

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“…Overproduction of Bip in strains expressing cutinase variants from Fusarium solani pisi did not affect the protein production capacity in A. awamori (40,41). On the other hand, overproduction of another ER lumenal chaperone, calnexin, has been shown to increase the production of Phanerochaete chrysosporium manganese peroxidase in A. niger up to fivefold (7). Thaumatin production in A. awamori was improved by PDIA overexpression up to fivefold.…”

Section: Discussionmentioning

confidence: 86%

Improvementof Foreign-Protein Production in Aspergillus niger var. awamori by Constitutive Induction of the Unfolded-ProteinResponse

Valkonen

Ward²,

Wang³

et al. 2003

Appl Environ Microbiol

103

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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.

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Section: Discussionmentioning

confidence: 86%

Improvementof Foreign-Protein Production in Aspergillus niger var. awamori by Constitutive Induction of the Unfolded-ProteinResponse

Valkonen

Ward²,

Wang³

et al. 2003

Appl Environ Microbiol

103

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“…In other cases, no effect on secretion of specific proteins has been observed (6,7,15,17,30), and even decreases in the secreted levels of the proteins studied have been reported (6,7,37).…”

Section: Discussionmentioning

confidence: 99%

Modulation of Aspergillus awamori Thaumatin Secretion by Modification of bipA Gene Expression

Lombraña

Moralejo

Pinto

et al. 2004

Appl Environ Microbiol

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Two different strains, Aspergillus awamori TGDTh-4 and A. awamori TGP-3 overexpressing a synthetic gene encoding the plant sweet protein thaumatin, showed an unfolded protein response. To facilitate protein secretion, the chaperone BiPA gene was expressed in A. awamori under control of the strong constitutive promoter of the gpdA gene. A good correlation was observed between the level of the bipA transcript in different strains and the amount of thaumatin secreted. Thaumatin secretion was increased 2-to 2.5-fold in transformants overexpressing the bipA gene compared with the parental strain. Secretion of the homologous proteins ␣-amylase and glucoamylase was not affected by the bipA gene overexpression. The requirement for BiPA for secretion of thaumatin was confirmed by attenuation of the endogenous bipA gene expression with an antisense RNA cassette. The decrease in bipA expression reduced the amount of secreted thaumatin up to 80% without affecting the secretion of the homologous ␣-amylase and glucoamylase proteins. The BiPA protein is, therefore, very important for secretion of some heterologous proteins, such as thaumatin in A. awamori.

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“…See Table S1 in the supplemental material for the corresponding ORF names. (2), whereas overexpression of the heat shock protein bipA resulted in increased levels of unprocessed fusion protein (15). These examples show a correlation between production levels of proteins and the transcript levels of genes involved in the secretion pathway.…”

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confidence: 92%

Spatial Differentiation in the Vegetative Mycelium of Aspergillus niger

et al. 2007

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Fungal mycelia are exposed to heterogenic substrates. The substrate in the central part of the colony has been (partly) degraded, whereas it is still unexplored at the periphery of the mycelium. We here assessed whether substrate heterogeneity is a main determinant of spatial gene expression in colonies of Aspergillus niger. This question was addressed by analyzing whole-genome gene expression in five concentric zones of 7-day-old maltose-and xylose-grown colonies. Expression profiles at the periphery and the center were clearly different. More than 25% of the active genes showed twofold differences in expression between the inner and outermost zones of the colony. Moreover, 9% of the genes were expressed in only one of the five concentric zones, showing that a considerable part of the genome is active in a restricted part of the colony only. Statistical analysis of expression profiles of colonies that had either been or not been transferred to fresh xylosecontaining medium showed that differential expression in a colony is due to the heterogeneity of the medium (e.g., genes involved in secretion, genes encoding proteases, and genes involved in xylose metabolism) as well as to medium-independent mechanisms (e.g., genes involved in nitrate metabolism and genes involved in cell wall synthesis and modification). Thus, we conclude that the mycelia of 7-day-old colonies of A. niger are highly differentiated. This conclusion is also indicated by the fact that distinct zones of the colony grow and secrete proteins, even after transfer to fresh medium.Filamentous fungi fulfill an essential role in global carbon cycling by degrading organic material. The organic material is colonized by a mycelium that consists of interconnected hyphae. These hyphae are exposed to a heterogenic substrate. The periphery of the colony is exposed to unexplored organic material, whereas its center is surrounded with a substrate that has been (partly) utilized. Little is known of how this heterogeneity affects cellular processes and gene expression in different parts of the mycelium. However, previous studies suggest that the vegetative colonizing mycelium is highly differentiated (11,21,24). Growth of Aspergillus niger and Phanerochaete chrysosporium mainly takes place in specific zones at the periphery and the center of the colony (11, 24). These zones also secrete proteins. For instance, glucoamylase is secreted at the periphery of an A. niger colony (24), whereas lignin peroxidase is secreted in the central growth zone of P. chrysosporium (11). Interestingly, the hyphae that release the peroxidase are morphologically distinct from the secreting hyphae at the periphery of the vegetative mycelium. The high degree of differentiation in fungal vegetative mycelia is also indicated by the fact that only a subset of growing hyphae at the periphery of an A. niger colony secrete glucoamylase (21, 24).Previous studies have shown that certain genes are differentially expressed in central and peripheral zones of the vegetative mycelium (11,18,21,25)....

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Calnexin Overexpression Increases Manganese Peroxidase Production in Aspergillus niger

Cited by 76 publications

References 47 publications

Improvementof Foreign-Protein Production in Aspergillus niger var. awamori by Constitutive Induction of the Unfolded-ProteinResponse

Improvementof Foreign-Protein Production in Aspergillus niger var. awamori by Constitutive Induction of the Unfolded-ProteinResponse

Modulation of Aspergillus awamori Thaumatin Secretion by Modification of bipA Gene Expression

Spatial Differentiation in the Vegetative Mycelium of Aspergillus niger

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