The effect of specific growth rate on protein synthesis and secretion in the filamentous fungus Trichoderma reesei

Pakula, Tiina; Salonen, Kalle; Uusitalo, Jaana; Penttilä, Merja

doi:10.1099/mic.0.27458-0

Cited by 96 publications

(75 citation statements)

References 36 publications

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“…The residual steady-state concentrations of D-glucose, D-galactose and lactose in the medium were 0?08-0?10 mM, 0?10-0?12 mM and 0?09-0?12 mM, respectively. Consistent with the results of Pakula et al (2005), we could not detect D-glucose or D-galactose in the lactose-grown cultures. In galactitol-limited cultures, the steady-state biomass concentration was 1?36±0?17 g l…”

Section: Carbon-limited Chemostat Cultivation Of H Jecorinasupporting

confidence: 81%

d-Galactose induces cellulase gene expression in Hypocrea jecorina at low growth rates

et al. 2006

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Lactose (1,4-O-b-D-galactopyranosyl-D-glucose) is a soluble and economic carbon source for the industrial production of cellulases or recombinant proteins by Hypocrea jecorina (anamorph Trichoderma reesei). The mechanism by which lactose induces cellulase formation is not understood. Recent data showed that the galactokinase step is essential for cellulase induction by lactose, but growth on D-galactose alone does not induce cellulases. Consequently, the hypothesis was tested that D-galactose may be an inducer only at a low growth rate, which is typically observed when growing on lactose. Carbon-limited chemostat cultivations of H. jecorina were therefore performed at different dilution rates with D-galactose, lactose, galactitol and D-glucose. Cellulase gene expression was monitored by using a strain carrying a fusion between the cbh2 (encoding cellobiohydrolase 2, Cel6A) promoter region and the Aspergillus niger glucose oxidase gene and by identification of the two major cellobiohydrolases Cel7A and Cel6A. The results show that D-galactose indeed induces cbh2 gene transcription and leads to Cel7A and Cel6A accumulation at a low (D=0?015 h "1 ) but not at higher dilution rates. At the same dilution rate, growth on D-glucose did not lead to cbh2 promoter activation or Cel6A formation but a basal level, lower than that observed on D-galactose, was detected for the carbon-catabolite-derepressible Cel7A. Lactose induced significantly higher cellulase levels at 0?015 h "1 than D-galactose and induced cellulases even at growth rates up to 0?042 h "1. Results of chemostats with an equimolar mixture of D-galactose and D-glucose essentially mimicked the behaviour on D-galactose alone, whereas an equimolar mixture of D-galactose and galactitol, the first intermediate of a recently described second pathway of D-galactose catabolism, led to cellulase induction at D=0?030 h "1 . It is concluded that D-galactose indeed induces cellulases at low growth rate and that the operation of the alternative pathway further increases this induction. However, under those conditions lactose is still a superior inducer for which the mechanism remains to be clarified.

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Section: Carbon-limited Chemostat Cultivation Of H Jecorinasupporting

confidence: 81%

d-Galactose induces cellulase gene expression in Hypocrea jecorina at low growth rates

et al. 2006

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“…Nutrient deprivation, such as in the absence of carbon source or presence of mannitol, a hexose that is not produced in the plant and is usually used by fungi as a carbohydrate reserve (Solomon et al, 2007), induced the highest protein secretion in comparison to all other carbon sources tested. This was not related to a low specific growth rate, as in Trichoderma reesei (Pakula et al, 2005), or to the general energy metabolism of M. perniciosa, as suggested by our results with GLY ( Figure 5A). Here, both non-fermentable carbon sources, mannitol and GLY, impaired growth ( Figure 1), but only mannitol could induce high secretory activity in M. perniciosa.…”

Section: Discussionsupporting

confidence: 63%

Carbon source-induced changes in the physiology of the cacao pathogen Moniliophthora perniciosa (Basidiomycetes) affect mycelial morphology and secretion of necrosis-inducing proteins

Alvim¹,

Mattos²,

Pirovani³

et al. 2009

Genet. Mol. Res.

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ABSTRACT. Quantitative and qualitative relationships were found between secreted proteins and their activity, and the hyphal morphology of Moniliophthora perniciosa, the causal agent of witches' broom disease in Theobroma cacao. This fungus was grown on fermentable and non-fermentable carbon sources; significant differences in mycelial morphology were observed and correlated with the carbon source. A biological assay performed with Nicotiana tabacum leaves revealed that the necrosis-related activity of extracellular fungal proteins also differed with carbon source. There were clear differences in the type and quantity of the secreted proteins. In addition, the expression of the cacao molecular chaperone BiP increased after treatment with secreted proteins, suggesting a physiological response to the fungus secretome. We suggest that the carbon source-dependent energy metabolism of M. perniciosa results in physiological alterations in protein expression and secretion; these may affect not only M. perniciosa growth, but also its ability to express pathogenicity proteins.

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“…Chemostat-type continuous cultivations (Ilyés et al, 2004;Karaffa et al, 2006;Pakula et al, 2005) are a useful means to investigate such interfering mechanisms.…”

Section: Discussionmentioning

confidence: 99%

Induction of extracellular β-galactosidase (Bga1) formation by d-galactose in Hypocrea jecorina is mediated by galactitol

et al. 2007

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The ability of Hypocrea jecorina (Trichoderma reesei) to grow on lactose strongly depends on the formation of an extracellular glycoside hydrolase (GH) family 35 b-galactosidase, encoded by the bga1 gene. Previous studies, using batch or transfer cultures of pregrown cells, had shown that bga1 is induced by lactose and D-galactose, but to a lesser extent by galactitol. To test whether the induction level is influenced by the different growth rates attainable on these carbon sources, bga1 expression was compared in carbon-limited chemostat cultivations at defined dilution (=specific growth) rates. The data showed that bga1 expression by lactose, D-galactose and galactitol positively correlated with the dilution rate, and that galactitol and D-galactose induced the highest activities of b-galactosidase at comparable growth rates. To know more about the actual inducer for b-galactosidase formation, its expression in H. jecorina strains impaired in the first steps of the two D-galactose-degrading pathways was compared. Induction by D-galactose and galactitol was still found in strains deleted in the galactokinase-encoding gene gal1, which is responsible for the first step of the Leloir pathway of D-galactose catabolism. However, in a strain deleted in the aldose/D-xylose reductase gene xyl1, which performs the reduction of D-galactose to galactitol in a recently identified second pathway, induction by D-galactose, but not by galactitol, was impaired. On the other hand, induction by D-galactose and galactitol was not affected in an L-arabinitol 4-dehydrogenase (lad1)-deleted strain which is impaired in the subsequent step of galactitol degradation. These results indicate that galactitol is the actual inducer of Bga1 formation during growth on D-galactose in H. jecorina.

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The effect of specific growth rate on protein synthesis and secretion in the filamentous fungus Trichoderma reesei

Cited by 96 publications

References 36 publications

d-Galactose induces cellulase gene expression in Hypocrea jecorina at low growth rates

d-Galactose induces cellulase gene expression in Hypocrea jecorina at low growth rates

Carbon source-induced changes in the physiology of the cacao pathogen Moniliophthora perniciosa (Basidiomycetes) affect mycelial morphology and secretion of necrosis-inducing proteins

Induction of extracellular β-galactosidase (Bga1) formation by d-galactose in Hypocrea jecorina is mediated by galactitol

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